/* ===================================================
   GIÁO TRÌNH LẬP TRÌNH VỚI AI - PROFESSIONAL STYLESHEET
   Version: 1.0 | By GitHub Copilot
   =================================================== */

/* ---- CSS VARIABLES ---- */
:root {
  --primary: #6C63FF;
  --primary-dark: #4B44CC;
  --primary-light: #A89BFF;
  --secondary: #00D4AA;
  --accent: #FF6B6B;
  --warning: #FFB347;
  --success: #52C41A;
  --info: #40A9FF;

  --bg-dark: #0D0F1A;
  --bg-card: #141828;
  --bg-sidebar: #0F1120;
  --bg-code: #1A1D2E;
  --bg-hover: #1E2235;

  --text-primary: #E8EAF6;
  --text-secondary: #9FA8DA;
  --text-muted: #5C6494;
  --text-code: #A8FF87;

  --border: rgba(108, 99, 255, 0.2);
  --border-light: rgba(255,255,255,0.06);
  --shadow: 0 4px 24px rgba(0,0,0,0.4);
  --shadow-card: 0 8px 32px rgba(108,99,255,0.12);
  --radius: 12px;
  --radius-sm: 8px;
  --transition: all 0.25s ease;

  --font-main: 'Inter', 'Segoe UI', sans-serif;
  --font-code: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;

  --sidebar-width: 280px;
  --header-height: 64px;
}

/* ---- RESET & BASE ---- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font-main);
  background: var(--bg-dark);
  color: var(--text-primary);
  line-height: 1.7;
  overflow-x: hidden;
}

/* ---- TYPOGRAPHY ---- */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.3;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}
h1 { font-size: 2.4rem; }
h2 { font-size: 1.9rem; }
h3 { font-size: 1.4rem; }
h4 { font-size: 1.15rem; }
p { margin-bottom: 1rem; color: var(--text-secondary); }
a { color: var(--primary-light); text-decoration: none; transition: var(--transition); }
a:hover { color: var(--secondary); }
strong { color: var(--text-primary); font-weight: 600; }
ul, ol { padding-left: 1.5rem; color: var(--text-secondary); }
li { margin-bottom: 0.4rem; }
hr { border: none; border-top: 1px solid var(--border-light); margin: 2rem 0; }
img { max-width: 100%; border-radius: var(--radius-sm); }

/* ---- LAYOUT ---- */
.layout {
  display: flex;
  min-height: 100vh;
}

/* ---- SIDEBAR ---- */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border-light);
  position: fixed;
  top: 0; left: 0;
  height: 100vh;
  overflow-y: auto;
  z-index: 100;
  transition: transform 0.3s ease;
  display: flex;
  flex-direction: column;
}
.sidebar::-webkit-scrollbar { width: 4px; }
.sidebar::-webkit-scrollbar-track { background: transparent; }
.sidebar::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }

.sidebar-logo {
  padding: 1.5rem 1.25rem;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.sidebar-logo .logo-icon {
  width: 38px; height: 38px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.1rem; font-weight: 800; color: #fff;
  flex-shrink: 0;
}
.sidebar-logo .logo-text { font-size: 0.85rem; font-weight: 700; line-height: 1.2; }
.sidebar-logo .logo-text span { display: block; color: var(--text-muted); font-weight: 400; font-size: 0.75rem; }

.sidebar-nav { padding: 1rem 0; flex: 1; }
.nav-section { margin-bottom: 0.25rem; }
.nav-section-title {
  padding: 0.5rem 1.25rem 0.25rem;
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.nav-item {
  display: flex;
  align-items: center;
  padding: 0.6rem 1.25rem;
  color: var(--text-secondary);
  font-size: 0.85rem;
  font-weight: 500;
  border-left: 3px solid transparent;
  transition: var(--transition);
  cursor: pointer;
  gap: 0.6rem;
}
.nav-item:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
  border-left-color: var(--primary);
}
.nav-item.active {
  background: rgba(108,99,255,0.12);
  color: var(--primary-light);
  border-left-color: var(--primary);
}
.nav-item .nav-num {
  width: 22px; height: 22px;
  background: var(--bg-code);
  border-radius: 6px;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.7rem; font-weight: 700;
  color: var(--text-muted);
  flex-shrink: 0;
}
.nav-item.active .nav-num {
  background: var(--primary);
  color: #fff;
}
.nav-item .nav-badge {
  margin-left: auto;
  padding: 1px 7px;
  border-radius: 99px;
  font-size: 0.65rem;
  font-weight: 600;
  background: rgba(0,212,170,0.15);
  color: var(--secondary);
}
.nav-item .nav-badge.new {
  background: rgba(255,107,107,0.15);
  color: var(--accent);
}
.sidebar-footer {
  padding: 1rem 1.25rem;
  border-top: 1px solid var(--border-light);
  font-size: 0.75rem;
  color: var(--text-muted);
  text-align: center;
}

/* ---- MAIN CONTENT ---- */
.main {
  margin-left: var(--sidebar-width);
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* ---- TOP HEADER ---- */
.topbar {
  height: var(--header-height);
  background: rgba(13,15,26,0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2rem;
  position: sticky; top: 0; z-index: 50;
}
.topbar-left { display: flex; align-items: center; gap: 1rem; }
.hamburger {
  display: none;
  background: none; border: none;
  color: var(--text-primary);
  font-size: 1.2rem; cursor: pointer;
  padding: 0.3rem;
}
.breadcrumb { display: flex; align-items: center; gap: 0.4rem; font-size: 0.82rem; color: var(--text-muted); }
.breadcrumb span { color: var(--text-muted); }
.breadcrumb .current { color: var(--text-primary); font-weight: 600; }
.topbar-actions { display: flex; align-items: center; gap: 0.75rem; }
.btn-topbar {
  padding: 0.4rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  border: 1px solid transparent;
}
.btn-topbar.outline {
  border-color: var(--border);
  color: var(--text-secondary);
  background: transparent;
}
.btn-topbar.outline:hover { border-color: var(--primary); color: var(--primary-light); }
.btn-topbar.primary {
  background: var(--primary);
  color: #fff;
}
.btn-topbar.primary:hover { background: var(--primary-dark); }

/* ---- PAGE CONTENT ---- */
.page-content {
  padding: 2.5rem 2.5rem 4rem;
  width: 100%;
}

/* ---- HERO / PAGE HEADER ---- */
.page-hero {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border-light);
}
.page-hero .module-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.3rem 0.9rem;
  border-radius: 99px;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 1rem;
  border: 1px solid;
}
.tag-purple { background: rgba(108,99,255,0.12); color: var(--primary-light); border-color: rgba(108,99,255,0.3); }
.tag-green  { background: rgba(0,212,170,0.1);  color: var(--secondary);      border-color: rgba(0,212,170,0.3); }
.tag-red    { background: rgba(255,107,107,0.1); color: var(--accent);         border-color: rgba(255,107,107,0.3); }
.tag-yellow { background: rgba(255,179,71,0.1);  color: var(--warning);        border-color: rgba(255,179,71,0.3); }
.tag-blue   { background: rgba(64,169,255,0.1);  color: var(--info);           border-color: rgba(64,169,255,0.3); }

.page-hero h1 { margin-bottom: 0.75rem; }
.page-hero .subtitle { font-size: 1.05rem; color: var(--text-secondary); max-width: 680px; }
.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border-light);
}
.meta-item { display: flex; align-items: center; gap: 0.4rem; font-size: 0.82rem; color: var(--text-muted); }
.meta-item strong { color: var(--text-primary); }

/* ---- CARDS ---- */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  transition: var(--transition);
}
.card:hover { border-color: var(--border); box-shadow: var(--shadow-card); }
.card-header { margin-bottom: 1rem; display: flex; align-items: center; gap: 0.75rem; }
.card-icon {
  width: 42px; height: 42px;
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.2rem;
  flex-shrink: 0;
}
.icon-purple { background: rgba(108,99,255,0.2); }
.icon-green  { background: rgba(0,212,170,0.15); }
.icon-red    { background: rgba(255,107,107,0.15); }
.icon-yellow { background: rgba(255,179,71,0.15); }
.icon-blue   { background: rgba(64,169,255,0.15); }

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.25rem;
  margin-bottom: 2rem;
}
.module-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: var(--transition);
  cursor: pointer;
  position: relative;
  overflow: hidden;
}
.module-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  transform: scaleX(0);
  transition: var(--transition);
  transform-origin: left;
}
.module-card:hover { border-color: var(--border); box-shadow: var(--shadow-card); transform: translateY(-2px); }
.module-card:hover::before { transform: scaleX(1); }
.module-card .module-num {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary-light);
  margin-bottom: 0.5rem;
}
.module-card h3 { font-size: 1rem; margin-bottom: 0.5rem; }
.module-card p { font-size: 0.82rem; color: var(--text-muted); margin: 0; }
.module-card .card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 1rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border-light);
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* ---- LESSON SECTIONS ---- */
.lesson-section {
  margin-bottom: 3rem;
}
.section-title {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}
.section-title h2 { margin: 0; }
.section-num {
  width: 32px; height: 32px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.75rem; font-weight: 800; color: #fff;
  flex-shrink: 0;
}

/* ---- CALLOUT BOXES ---- */
.callout {
  border-radius: var(--radius-sm);
  padding: 1.1rem 1.25rem;
  margin: 1.25rem 0;
  display: flex;
  gap: 0.75rem;
  border-left: 3px solid;
}
.callout-icon { font-size: 1.1rem; flex-shrink: 0; margin-top: 1px; }
.callout-content { flex: 1; }
.callout-content strong { display: block; margin-bottom: 0.25rem; font-size: 0.9rem; }
.callout-content p { margin: 0; font-size: 0.875rem; }
.callout.info    { background: rgba(64,169,255,0.08);  border-color: var(--info);    }
.callout.info    .callout-icon { color: var(--info); }
.callout.success { background: rgba(82,196,26,0.08);   border-color: var(--success); }
.callout.success .callout-icon { color: var(--success); }
.callout.warning { background: rgba(255,179,71,0.08);  border-color: var(--warning); }
.callout.warning .callout-icon { color: var(--warning); }
.callout.danger  { background: rgba(255,107,107,0.08); border-color: var(--accent);  }
.callout.danger  .callout-icon { color: var(--accent); }
.callout.tip     { background: rgba(108,99,255,0.08);  border-color: var(--primary); }
.callout.tip     .callout-icon { color: var(--primary-light); }

/* ---- CODE BLOCKS ---- */
.code-block {
  margin: 1.25rem 0;
  border-radius: var(--radius-sm);
  overflow: hidden;
  border: 1px solid var(--border-light);
}
.code-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.6rem 1rem;
  background: rgba(255,255,255,0.04);
  border-bottom: 1px solid var(--border-light);
}
.code-lang {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.code-copy {
  font-size: 0.72rem;
  color: var(--text-muted);
  background: none; border: none;
  cursor: pointer; padding: 0.2rem 0.5rem;
  border-radius: 4px;
  transition: var(--transition);
}
.code-copy:hover { color: var(--text-primary); background: var(--border-light); }
pre {
  margin: 0;
  padding: 1.25rem;
  background: var(--bg-code);
  overflow-x: auto;
  font-family: var(--font-code);
  font-size: 0.865rem;
  line-height: 1.6;
}
pre code { background: none; padding: 0; border-radius: 0; font-size: inherit; }
code {
  font-family: var(--font-code);
  font-size: 0.875em;
  background: rgba(108,99,255,0.15);
  color: var(--primary-light);
  padding: 0.1em 0.4em;
  border-radius: 4px;
}

/* ---- STEPS / PROCEDURE ---- */
.steps { counter-reset: step; list-style: none; padding: 0; }
.steps li {
  counter-increment: step;
  display: flex;
  gap: 1rem;
  margin-bottom: 1.25rem;
  align-items: flex-start;
}
.steps li::before {
  content: counter(step);
  width: 28px; height: 28px;
  min-width: 28px;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.75rem; font-weight: 700; color: #fff;
  margin-top: 2px;
}
.steps li .step-content strong { display: block; margin-bottom: 0.25rem; color: var(--text-primary); }
.steps li .step-content p { margin: 0; font-size: 0.875rem; }

/* ---- COMPARISON TABLE ---- */
.compare-table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.25rem 0;
  font-size: 0.875rem;
  border-radius: var(--radius-sm);
  overflow: hidden;
}
.compare-table th {
  background: rgba(108,99,255,0.2);
  color: var(--primary-light);
  padding: 0.75rem 1rem;
  text-align: left;
  font-weight: 700;
  font-size: 0.8rem;
  letter-spacing: 0.04em;
}
.compare-table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border-light);
  color: var(--text-secondary);
}
.compare-table tr:nth-child(even) td { background: rgba(255,255,255,0.02); }
.compare-table tr:last-child td { border-bottom: none; }
.compare-table tr:hover td { background: var(--bg-hover); }
.td-good { color: var(--success) !important; font-weight: 600; }
.td-bad  { color: var(--accent) !important; }
.td-mid  { color: var(--warning) !important; }

/* ---- EXERCISE BOX ---- */
.exercise-box {
  background: linear-gradient(135deg, rgba(108,99,255,0.08), rgba(0,212,170,0.05));
  border: 1px solid rgba(108,99,255,0.25);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin: 2rem 0;
}
.exercise-box .exercise-header {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 1rem;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary-light);
}
.exercise-box h4 { margin-bottom: 0.5rem; font-size: 1rem; }
.exercise-box p  { font-size: 0.875rem; margin-bottom: 0.5rem; }
.task-list { list-style: none; padding: 0; }
.task-list li {
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  padding: 0.4rem 0;
  font-size: 0.875rem;
  color: var(--text-secondary);
}
.task-list li::before {
  content: '□';
  color: var(--primary-light);
  font-size: 1rem;
  line-height: 1.4;
  flex-shrink: 0;
}

/* ---- OBJECTIVES BOX ---- */
.objectives {
  background: rgba(0,212,170,0.05);
  border: 1px solid rgba(0,212,170,0.2);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 2rem;
}
.objectives h4 {
  color: var(--secondary);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 0.75rem;
}
.objectives ul { list-style: none; padding: 0; }
.objectives ul li {
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  font-size: 0.875rem;
  padding: 0.25rem 0;
}
.objectives ul li::before { content: '✓'; color: var(--secondary); font-weight: 700; }

/* ---- KEY TERMS ---- */
.key-terms {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.75rem;
  margin: 1.25rem 0;
}
.term-card {
  background: var(--bg-code);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  padding: 0.9rem 1rem;
}
.term-card .term { font-weight: 700; color: var(--primary-light); font-size: 0.9rem; margin-bottom: 0.3rem; }
.term-card .def  { font-size: 0.8rem; color: var(--text-muted); line-height: 1.5; }

/* ---- PROGRESS BAR ---- */
.progress-container {
  margin: 0.75rem 0;
}
.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 0.3rem;
}
.progress-bar {
  height: 6px;
  background: var(--border-light);
  border-radius: 99px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  border-radius: 99px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  transition: width 0.6s ease;
}

/* ---- QUOTE ---- */
blockquote {
  border-left: 3px solid var(--primary);
  padding: 0.75rem 1.25rem;
  margin: 1.25rem 0;
  background: rgba(108,99,255,0.06);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-style: italic;
  color: var(--text-secondary);
}
blockquote cite {
  display: block;
  margin-top: 0.4rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  font-style: normal;
}

/* ---- LESSON NAVIGATION ---- */
.lesson-nav {
  display: flex;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-light);
}
.lesson-nav-btn {
  flex: 1;
  padding: 1rem 1.25rem;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
  display: block;
}
.lesson-nav-btn:hover { border-color: var(--primary); box-shadow: var(--shadow-card); }
.lesson-nav-btn .dir {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 0.3rem;
}
.lesson-nav-btn .title { font-weight: 600; color: var(--text-primary); font-size: 0.9rem; }
.lesson-nav-btn.next { text-align: right; }

/* ---- SUMMARY / RECAP ---- */
.recap-box {
  background: linear-gradient(135deg, rgba(108,99,255,0.1), rgba(0,212,170,0.06));
  border: 1px solid rgba(108,99,255,0.25);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin: 2rem 0;
}
.recap-box h4 { color: var(--primary-light); margin-bottom: 0.75rem; font-size: 0.9rem; text-transform: uppercase; letter-spacing: 0.06em; }
.recap-box ul { list-style: none; padding: 0; }
.recap-box ul li {
  font-size: 0.875rem;
  color: var(--text-secondary);
  padding: 0.2rem 0;
  padding-left: 1rem;
  position: relative;
}
.recap-box ul li::before {
  content: '→';
  position: absolute; left: 0;
  color: var(--primary-light);
}

/* ---- INDEX / HERO SECTION ---- */
.hero-section {
  background: linear-gradient(135deg, rgba(108,99,255,0.15) 0%, rgba(0,212,170,0.08) 50%, transparent 100%);
  border-radius: var(--radius);
  padding: 3rem;
  margin-bottom: 3rem;
  border: 1px solid var(--border);
  position: relative;
  overflow: hidden;
}
.hero-section::before {
  content: '';
  position: absolute;
  top: -50%; right: -20%;
  width: 400px; height: 400px;
  background: radial-gradient(circle, rgba(108,99,255,0.15), transparent 70%);
  pointer-events: none;
}
.hero-section .course-badge {
  display: inline-flex; align-items: center; gap: 0.5rem;
  background: rgba(108,99,255,0.2);
  border: 1px solid rgba(108,99,255,0.4);
  color: var(--primary-light);
  padding: 0.35rem 0.9rem;
  border-radius: 99px;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 1.25rem;
}
.hero-section h1 {
  font-size: 2.8rem;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, #fff 30%, var(--primary-light) 70%, var(--secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-section .subtitle { font-size: 1.1rem; max-width: 600px; margin-bottom: 2rem; }
.hero-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 2rem;
  margin-top: 2rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-light);
}
.stat-item { text-align: center; }
.stat-item .num { font-size: 2rem; font-weight: 800; color: var(--text-primary); line-height: 1; }
.stat-item .label { font-size: 0.78rem; color: var(--text-muted); margin-top: 0.25rem; }

/* ---- BUTTONS ---- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.7rem 1.5rem;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  border: 1px solid transparent;
  text-decoration: none;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); color: #fff; transform: translateY(-1px); box-shadow: 0 4px 16px rgba(108,99,255,0.4); }
.btn-secondary { background: rgba(0,212,170,0.12); color: var(--secondary); border-color: rgba(0,212,170,0.3); }
.btn-secondary:hover { background: rgba(0,212,170,0.2); color: var(--secondary); }
.btn-outline { border-color: var(--border); color: var(--text-secondary); background: transparent; }
.btn-outline:hover { border-color: var(--primary); color: var(--primary-light); }

/* ---- TOOLS GRID ---- */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin: 1.25rem 0;
}
.tool-card {
  background: var(--bg-code);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  padding: 1.1rem 1.25rem;
  transition: var(--transition);
}
.tool-card:hover { border-color: var(--primary); transform: translateY(-2px); }
.tool-card .tool-logo { font-size: 1.8rem; margin-bottom: 0.5rem; }
.tool-card .tool-name { font-weight: 700; font-size: 0.9rem; color: var(--text-primary); margin-bottom: 0.2rem; }
.tool-card .tool-desc { font-size: 0.78rem; color: var(--text-muted); }
.tool-card .tool-tags { margin-top: 0.6rem; display: flex; flex-wrap: wrap; gap: 0.3rem; }
.tool-tag {
  font-size: 0.65rem;
  padding: 0.1rem 0.5rem;
  border-radius: 99px;
  background: rgba(108,99,255,0.15);
  color: var(--primary-light);
  font-weight: 600;
}

/* ---- RESPONSIVE ---- */
@media (max-width: 1024px) {
  .sidebar { transform: translateX(-100%); }
  .sidebar.open { transform: translateX(0); }
  .main { margin-left: 0; }
  .hamburger { display: block; }
  .page-content { padding: 1.5rem; }
}
@media (max-width: 640px) {
  .hero-section { padding: 1.75rem; }
  .hero-section h1 { font-size: 1.8rem; }
  .card-grid { grid-template-columns: 1fr; }
  .lesson-nav { flex-direction: column; }
  .tools-grid { grid-template-columns: 1fr 1fr; }
}

/* ---- PRINT ---- */
@media print {
  .sidebar, .topbar, .lesson-nav { display: none !important; }
  .main { margin-left: 0 !important; }
  body { background: #fff; color: #000; }
  pre { border: 1px solid #ccc; }
}

/* ---- ANIMATIONS ---- */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}
.fade-in { animation: fadeInUp 0.5s ease both; }
.fade-in-1 { animation-delay: 0.1s; }
.fade-in-2 { animation-delay: 0.2s; }
.fade-in-3 { animation-delay: 0.3s; }

/* ---- SYNTAX HIGHLIGHT OVERRIDE ---- */
.hljs { background: var(--bg-code) !important; color: #abb2bf; }
.hljs-keyword { color: #c678dd; }
.hljs-string  { color: #98c379; }
.hljs-comment { color: #5c6370; font-style: italic; }
.hljs-number  { color: #d19a66; }
.hljs-function .hljs-title { color: #61afef; }
.hljs-class .hljs-title    { color: #e5c07b; }
.hljs-variable             { color: #e06c75; }
.hljs-attr                 { color: #d19a66; }
.hljs-built_in             { color: #56b6c2; }
.hljs-params               { color: #abb2bf; }
.hljs-operator             { color: #56b6c2; }

/* ---- CUSTOM SCROLLBAR ---- */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--bg-dark); }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--primary); }

/* ---- OVERLAY (mobile sidebar) ---- */
.overlay {
  display: none;
  position: fixed; inset: 0;
  background: rgba(0,0,0,0.6);
  z-index: 99;
}
.overlay.show { display: block; }

/* ---- SITE FOOTER ---- */
.site-footer {
  background: var(--bg-sidebar);
  border-top: 1px solid var(--border-light);
  padding: 2.5rem 2.5rem 1.75rem;
  margin-top: auto;
}
.footer-inner {
  max-width: 900px;
}
.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  margin-bottom: 1.25rem;
}
.footer-logo {
  width: 40px; height: 40px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1rem; font-weight: 800; color: #fff;
  flex-shrink: 0;
}
.footer-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.2;
}
.footer-copy {
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-top: 0.15rem;
}
.footer-copy strong { color: var(--primary-light); }
.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-light);
}
.footer-links a {
  font-size: 0.82rem;
  color: var(--text-muted);
  text-decoration: none;
  transition: var(--transition);
}
.footer-links a:hover { color: var(--primary-light); }
.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
}
.footer-legal {
  font-size: 0.75rem;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.footer-legal span { opacity: 0.5; }
.footer-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  background: rgba(108,99,255,0.15);
  color: var(--primary-light);
  border: 1px solid rgba(108,99,255,0.3);
  padding: 0.25rem 0.75rem;
  border-radius: 99px;
}

/* ---- SIDEBAR COPYRIGHT ---- */
.sidebar-copyright {
  font-size: 0.7rem;
  color: var(--text-muted);
  text-align: center;
  margin-top: 0.75rem;
  line-height: 1.6;
}
.sidebar-copyright strong { color: var(--primary-light); font-weight: 700; }

/* ---- AUTHOR SECTION ---- */
.author-card {
  display: flex;
  align-items: flex-start;
  gap: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius);
  padding: 2rem;
  margin-bottom: 1.5rem;
  transition: var(--transition);
}
.author-card:hover { border-color: var(--primary); box-shadow: var(--shadow-card); }
.author-avatar {
  width: 72px; height: 72px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  display: flex; align-items: center; justify-content: center;
  font-size: 1.8rem;
  font-weight: 800;
  color: #fff;
  flex-shrink: 0;
  border: 3px solid rgba(108,99,255,0.3);
}
.author-info { flex: 1; }
.author-name {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.2rem;
}
.author-role {
  font-size: 0.8rem;
  color: var(--primary-light);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.75rem;
}
.author-bio { font-size: 0.875rem; color: var(--text-secondary); margin-bottom: 0.75rem; }
.author-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}
.author-tag {
  font-size: 0.72rem;
  padding: 0.2rem 0.6rem;
  border-radius: 99px;
  background: rgba(0,212,170,0.1);
  color: var(--secondary);
  border: 1px solid rgba(0,212,170,0.25);
  font-weight: 600;
}

/* ---- TIP BOX (ThanhDoIT Tips) ---- */
.tip-box {
  background: linear-gradient(135deg, rgba(255,179,71,0.08), rgba(255,107,107,0.05));
  border: 1px solid rgba(255,179,71,0.3);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin: 2rem 0;
}
.tip-box-header {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 1rem;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--warning);
}
.tip-box ul { list-style: none; padding: 0; margin: 0; }
.tip-box ul li {
  display: flex;
  gap: 0.6rem;
  padding: 0.45rem 0;
  font-size: 0.875rem;
  color: var(--text-secondary);
  border-bottom: 1px solid rgba(255,255,255,0.04);
}
.tip-box ul li:last-child { border-bottom: none; }
.tip-box ul li::before { content: '⚡'; flex-shrink: 0; }

/* ---- EXTRA: Step component (non-list) ---- */
.steps:not(ol) { display: flex; flex-direction: column; gap: 1rem; }
.step { display: flex; gap: 1rem; align-items: flex-start; }
.step-num {
  width: 32px; height: 32px; min-width: 32px;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.8rem; font-weight: 800; color: #fff;
  margin-top: 2px; flex-shrink: 0;
}
.step-body h4 { margin-bottom: 0.25rem; font-size: 0.95rem; }
.step-body p  { margin: 0; font-size: 0.875rem; color: var(--text-secondary); }

/* ============================================================
   COMPLETION BANNER
   ============================================================ */
.completion-banner {
  background: linear-gradient(135deg, rgba(108,99,255,0.15) 0%, rgba(0,212,170,0.15) 100%);
  border: 1px solid rgba(108,99,255,0.3);
  border-radius: 16px;
  padding: 2.5rem;
  text-align: center;
  margin: 2rem 0;
}
.completion-icon {
  font-size: 4rem;
  line-height: 1;
  margin-bottom: 1rem;
}
.completion-banner h2 {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.completion-banner p {
  color: var(--text-muted);
  font-size: 1.05rem;
  max-width: 600px;
  margin: 0 auto;
}
/* ============================================================
   ANTI-FLASH GATE — hides content until access check completes
   ============================================================ */
html.gate-pending .main,
html.gate-pending .sidebar {
  visibility: hidden;
}

/* ============================================================
   CONTENT ACCESS GATE (chapter pages)
   ============================================================ */
#content-gate {
  position: fixed;
  inset: 0;
  z-index: 99999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}
.gate-overlay {
  position: absolute;
  inset: 0;
  background: var(--bg-dark, #0D0F1A);
}
.gate-panel {
  position: relative;
  z-index: 1;
  background: var(--bg-card, #141828);
  border: 1px solid rgba(108,99,255,0.3);
  border-radius: 20px;
  padding: 2.5rem 2rem;
  width: 100%;
  max-width: 440px;
  text-align: center;
  box-shadow: 0 24px 60px rgba(0,0,0,0.65), 0 0 0 1px rgba(108,99,255,0.08);
  animation: gatePop 0.35s cubic-bezier(0.34,1.56,0.64,1) both;
}
@keyframes gatePop {
  from { opacity:0; transform:scale(0.92) translateY(16px); }
  to   { opacity:1; transform:scale(1) translateY(0); }
}
.gate-logo-wrap {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}
.gate-logo-icon {
  width: 52px; height: 52px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  border-radius: 14px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.15rem; font-weight: 800; color: #fff;
  box-shadow: 0 6px 20px rgba(108,99,255,0.35);
}
.gate-logo-text {
  font-size: 1rem; font-weight: 700;
  color: var(--text-primary, #E8EAFB);
}
.gate-heading {
  font-size: 1.35rem; font-weight: 700;
  color: var(--text-primary, #E8EAFB);
  margin-bottom: 0.5rem;
}
.gate-desc {
  color: var(--text-muted, #8892B0);
  font-size: 0.875rem;
  margin-bottom: 1.75rem;
  line-height: 1.6;
}
.gate-form {
  display: flex; gap: 0.5rem;
  margin-bottom: 0.75rem;
}
.gate-input {
  flex: 1;
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 10px;
  padding: 0.75rem 1rem;
  color: var(--text-primary, #E8EAFB);
  font-size: 1rem;
  font-family: 'JetBrains Mono', monospace;
  letter-spacing: 0.06em;
  transition: border-color 0.2s, box-shadow 0.2s;
  min-width: 0;
}
.gate-input:focus {
  outline: none;
  border-color: var(--primary, #6C63FF);
  box-shadow: 0 0 0 3px rgba(108,99,255,0.18);
}
.gate-submit {
  background: linear-gradient(135deg, var(--primary), #8B83FF);
  color: #fff; border: none; border-radius: 10px;
  padding: 0.75rem 1.1rem;
  font-size: 0.875rem; font-weight: 700;
  cursor: pointer; white-space: nowrap;
  transition: opacity 0.2s, transform 0.12s;
  flex-shrink: 0;
}
.gate-submit:hover:not(:disabled) { opacity: 0.9; }
.gate-submit:active:not(:disabled) { transform: scale(0.97); }
.gate-submit:disabled { opacity: 0.55; cursor: not-allowed; }
.gate-feedback {
  font-size: 0.83rem; min-height: 1.4em;
  margin-bottom: 1rem; line-height: 1.5;
}
.gate-feedback.success { color: var(--secondary, #00D4AA); }
.gate-feedback.error   { color: #FF6B6B; }
.gate-footer-links {
  display: flex; justify-content: center;
  align-items: center; gap: 0.75rem;
  font-size: 0.8rem;
}
.gate-link { color: var(--primary-light, #8B83FF); text-decoration: none; }
.gate-link:hover { text-decoration: underline; }
.gate-sep { color: var(--text-muted); }
#content-gate.gate-exit {
  animation: gateExit 0.55s ease forwards;
}
@keyframes gateExit {
  to { opacity: 0; transform: scale(0.95); }
}

/* Access badge in topbar */
.access-active-badge {
  display: inline-flex; align-items: center; gap: 0.3rem;
  background: rgba(0,212,170,0.12);
  color: var(--secondary, #00D4AA);
  border: 1px solid rgba(0,212,170,0.28);
  border-radius: 20px; padding: 0.22rem 0.75rem;
  font-size: 0.75rem; font-weight: 600;
}

/* ============================================================
   PAYMENT MODAL (index.html)
   ============================================================ */
.pay-modal {
  position: fixed; inset: 0; z-index: 9998;
  display: flex; align-items: center; justify-content: center;
  padding: 1rem;
  opacity: 0; pointer-events: none;
  transition: opacity 0.25s;
}
.pay-modal.open {
  opacity: 1; pointer-events: auto;
}
.pay-backdrop {
  position: absolute; inset: 0;
  background: rgba(5,7,15,0.82);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  cursor: pointer;
}
.pay-dialog {
  position: relative; z-index: 1;
  background: var(--bg-card, #141828);
  border: 1px solid rgba(108,99,255,0.22);
  border-radius: 20px;
  width: 100%; max-width: 640px;
  max-height: 90vh; overflow-y: auto;
  display: flex; flex-direction: column;
  box-shadow: 0 32px 80px rgba(0,0,0,0.65);
  transform: translateY(20px) scale(0.97);
  transition: transform 0.25s cubic-bezier(0.34,1.2,0.64,1);
}
.pay-modal.open .pay-dialog {
  transform: translateY(0) scale(1);
}
.pay-close {
  position: absolute; top: 1rem; right: 1rem; z-index: 2;
  background: rgba(255,255,255,0.07); border: none;
  color: var(--text-muted); width: 32px; height: 32px;
  border-radius: 8px; cursor: pointer; font-size: 1rem;
  transition: background 0.2s;
}
.pay-close:hover { background: rgba(255,255,255,0.14); }
.pay-tabs {
  display: flex; border-bottom: 1px solid var(--border, rgba(255,255,255,0.08));
  padding: 1rem 1.5rem 0;
  flex-shrink: 0;
}
.pay-tab {
  padding: 0.55rem 1rem;
  background: none; border: none;
  color: var(--text-muted, #8892B0);
  font-size: 0.82rem; font-weight: 600;
  cursor: pointer;
  border-bottom: 2px solid transparent; margin-bottom: -1px;
  transition: color 0.2s;
}
.pay-tab:hover { color: var(--text-primary, #E8EAFB); }
.pay-tab.active {
  color: var(--primary-light, #8B83FF);
  border-bottom-color: var(--primary, #6C63FF);
}
.pay-tab-content { display: none; padding: 1.5rem; }
.pay-tab-content.active { display: block; }

/* Roadmap tab */
.pay-hero-row {
  display: flex; align-items: flex-start;
  justify-content: space-between; gap: 1rem;
  margin-bottom: 1.25rem; flex-wrap: wrap;
}
.pay-hero-row h2 { font-size: 1.25rem; font-weight: 700; margin: 0; }
.pay-price-tag {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: #fff; border-radius: 12px;
  padding: 0.45rem 1.1rem;
  font-size: 1.1rem; font-weight: 800;
  white-space: nowrap; flex-shrink: 0;
}
.pay-features {
  display: grid; grid-template-columns: 1fr 1fr;
  gap: 0.45rem; margin-bottom: 1.25rem;
}
@media (max-width: 500px) { .pay-features { grid-template-columns: 1fr; } }
.pay-feature {
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.07);
  border-radius: 8px; padding: 0.45rem 0.75rem;
  font-size: 0.82rem; color: var(--text-secondary, #A8B2D8);
}
.pay-roadmap { margin-bottom: 1.5rem; }
.pay-roadmap-item {
  display: flex; align-items: center; gap: 0.75rem;
  padding: 0.6rem 0;
  border-bottom: 1px solid rgba(255,255,255,0.05);
  font-size: 0.85rem; color: var(--text-secondary, #A8B2D8);
}
.pay-roadmap-item:last-child { border-bottom: none; }
.pay-roadmap-num {
  background: rgba(108,99,255,0.18); color: var(--primary-light, #8B83FF);
  border-radius: 6px; padding: 0.18rem 0.5rem;
  font-size: 0.72rem; font-weight: 700;
  min-width: 34px; text-align: center; flex-shrink: 0;
}
.pay-next-btn {
  width: 100%; padding: 0.85rem;
  background: linear-gradient(135deg, var(--primary), #8B83FF);
  color: #fff; border: none; border-radius: 12px;
  font-size: 0.95rem; font-weight: 700;
  cursor: pointer; transition: opacity 0.2s, transform 0.12s;
}
.pay-next-btn:hover { opacity: 0.9; }
.pay-next-btn:active { transform: scale(0.98); }

/* Payment tab */
.pay-bank-card {
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 14px; padding: 1.25rem;
  margin-bottom: 1.1rem;
}
.pay-bank-title {
  font-size: 0.75rem; text-transform: uppercase;
  letter-spacing: 0.08em; color: var(--text-muted);
  margin-bottom: 0.85rem; font-weight: 600;
}
.pay-bank-row {
  display: flex; justify-content: space-between; align-items: center;
  padding: 0.45rem 0;
  border-bottom: 1px solid rgba(255,255,255,0.05);
  font-size: 0.875rem; gap: 0.5rem;
}
.pay-bank-row:last-child { border-bottom: none; }
.pay-bank-label { color: var(--text-muted); flex-shrink: 0; }
.pay-bank-value { font-weight: 600; color: var(--text-primary); text-align: right; }
.pay-bank-value.accent { color: var(--secondary, #00D4AA); font-family: 'JetBrains Mono', monospace; }
.pay-bank-value.price-val { color: #FF9800; font-size: 1.05rem; }
.pay-copy-btn {
  background: rgba(108,99,255,0.14);
  color: var(--primary-light, #8B83FF);
  border: 1px solid rgba(108,99,255,0.25);
  border-radius: 6px; padding: 0.18rem 0.55rem;
  font-size: 0.7rem; cursor: pointer; font-weight: 600;
  white-space: nowrap; flex-shrink: 0;
}
.pay-copy-btn:hover { background: rgba(108,99,255,0.25); }
.pay-ref-box {
  background: rgba(0,212,170,0.08);
  border: 1px solid rgba(0,212,170,0.25);
  border-radius: 12px; padding: 1rem;
  text-align: center; margin-bottom: 1.1rem;
}
.pay-ref-label {
  font-size: 0.78rem; color: var(--text-muted); margin-bottom: 0.35rem;
}
.pay-ref-value {
  font-size: 1.6rem; font-weight: 800;
  font-family: 'JetBrains Mono', monospace;
  color: var(--secondary, #00D4AA); letter-spacing: 0.1em;
}
.pay-note-box {
  background: rgba(255,152,0,0.07);
  border: 1px solid rgba(255,152,0,0.2);
  border-left: 3px solid #FF9800;
  border-radius: 8px; padding: 0.7rem 1rem;
  font-size: 0.8rem; color: #FFB74D;
  margin-bottom: 1.1rem; line-height: 1.65;
}

/* Activate tab */
.pay-activate-label {
  display: block; font-size: 0.83rem;
  color: var(--text-muted); margin-bottom: 0.55rem; font-weight: 500;
}
.pay-activate-input {
  width: 100%;
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 12px; padding: 0.9rem 1rem;
  color: var(--text-primary);
  font-size: 1.15rem; font-family: 'JetBrains Mono', monospace;
  letter-spacing: 0.1em; text-align: center; text-transform: uppercase;
  margin-bottom: 1rem; box-sizing: border-box;
  transition: border-color 0.2s, box-shadow 0.2s;
}
.pay-activate-input:focus {
  outline: none; border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(108,99,255,0.15);
}
.pay-activate-btn {
  width: 100%; padding: 0.9rem;
  background: linear-gradient(135deg, var(--secondary), #00B894);
  color: #fff; border: none; border-radius: 12px;
  font-size: 1rem; font-weight: 700;
  cursor: pointer; transition: opacity 0.2s, transform 0.12s;
  margin-bottom: 0.75rem;
}
.pay-activate-btn:hover:not(:disabled) { opacity: 0.9; }
.pay-activate-btn:disabled { opacity: 0.55; cursor: not-allowed; }
.pay-activate-msg {
  min-height: 1.5em; font-size: 0.875rem;
  text-align: center; line-height: 1.5;
}
.pay-activate-msg.success { color: var(--secondary, #00D4AA); }
.pay-activate-msg.error   { color: #FF6B6B; }

/* ============================================================
   HERO ENHANCEMENTS (index.html)
   ============================================================ */
.hero-badge-row {
  display: flex; flex-wrap: wrap; gap: 0.5rem;
  justify-content: center; margin-bottom: 1.25rem;
}
.hero-badge-pill {
  background: rgba(108,99,255,0.15);
  border: 1px solid rgba(108,99,255,0.3);
  color: var(--primary-light, #8B83FF);
  border-radius: 20px; padding: 0.28rem 0.85rem;
  font-size: 0.78rem; font-weight: 600;
}
.hero-badge-pill.green {
  background: rgba(0,212,170,0.12);
  border-color: rgba(0,212,170,0.3);
  color: var(--secondary, #00D4AA);
}
.hero-cta-group {
  display: flex; gap: 0.75rem; flex-wrap: wrap; justify-content: center;
  margin-bottom: 1.5rem;
}
.btn-hero-primary {
  display: inline-flex; align-items: center; gap: 0.5rem;
  background: linear-gradient(135deg, var(--primary), #8B83FF);
  color: #fff; border: none; border-radius: 12px;
  padding: 0.9rem 2rem; font-size: 1rem; font-weight: 700;
  cursor: pointer; text-decoration: none;
  box-shadow: 0 6px 24px rgba(108,99,255,0.4);
  transition: transform 0.15s, box-shadow 0.15s, opacity 0.15s;
}
.btn-hero-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 32px rgba(108,99,255,0.55);
  opacity: 0.95;
}
.btn-hero-outline {
  display: inline-flex; align-items: center; gap: 0.5rem;
  background: rgba(255,255,255,0.06);
  color: var(--text-primary, #E8EAFB);
  border: 1px solid rgba(255,255,255,0.15);
  border-radius: 12px; padding: 0.9rem 1.75rem;
  font-size: 1rem; font-weight: 600; cursor: pointer;
  text-decoration: none;
  transition: background 0.2s, border-color 0.2s;
}
.btn-hero-outline:hover {
  background: rgba(255,255,255,0.1);
  border-color: rgba(255,255,255,0.25);
}
.social-proof-row {
  display: flex; align-items: center; justify-content: center;
  gap: 1.25rem; flex-wrap: wrap;
  margin-top: 1rem; font-size: 0.82rem; color: var(--text-muted);
}
.social-proof-item { display: flex; align-items: center; gap: 0.35rem; }
.stars { color: #FFD700; letter-spacing: 1px; }
/* ═══════════════════════════════════════════════════════════
   LUXURY VIP REDESIGN — Homepage 2026
   ThanhDoIT · Lập Trình Với AI
═══════════════════════════════════════════════════════════ */
:root {
  --lux-gold: #C9A227;
  --lux-gold-light: #F0C040;
  --lux-gold-glow: rgba(201,162,39,0.25);
}

/* Gold gradient text */
.gold-text {
  background: linear-gradient(135deg, var(--lux-gold), var(--lux-gold-light), var(--lux-gold));
  background-size: 200% auto;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: goldShimmer 4s linear infinite;
}
@keyframes goldShimmer { 0%,100%{background-position:0% 50%} 50%{background-position:100% 50%} }

/* ── LUXURY HERO ────────────────────────────────────────── */
.lux-hero {
  margin-left: -2.5rem;
  margin-right: -2.5rem;
  padding-left: 2.5rem;
  padding-right: 2.5rem;
  position: relative;
  padding: 4.5rem 0 3.5rem;
  overflow: hidden;
  text-align: center;
}
.lux-hero::before {
  content: '';
  position: absolute; inset: 0;
  background: radial-gradient(ellipse 85% 65% at 50% 0%, rgba(108,99,255,0.18) 0%, transparent 70%),
              radial-gradient(ellipse 40% 30% at 80% 60%, rgba(201,162,39,0.08) 0%, transparent 60%);
  pointer-events: none;
}
.lux-orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(70px);
  pointer-events: none;
  opacity: 0.55;
}
.lux-orb-1 { width: 450px; height: 450px; background: rgba(108,99,255,0.14); top: -120px; left: -130px; animation: orbFloat 9s ease-in-out infinite; }
.lux-orb-2 { width: 320px; height: 320px; background: rgba(201,162,39,0.09); bottom: -60px; right: -90px; animation: orbFloat 11s ease-in-out infinite reverse; }
.lux-orb-3 { width: 220px; height: 220px; background: rgba(0,212,170,0.07); top: 35%; left: 35%; animation: orbFloat 13s ease-in-out infinite; }
@keyframes orbFloat {
  0%,100% { transform: translate(0,0) scale(1); }
  33%      { transform: translate(18px,-12px) scale(1.04); }
  66%      { transform: translate(-10px,10px) scale(0.97); }
}
.lux-hero-inner { position: relative; z-index: 1; max-width: 920px; margin: 0 auto; }

/* Badge row */
.lux-badge-row { display: flex; gap: 0.6rem; justify-content: center; flex-wrap: wrap; margin-bottom: 2rem; }
.lux-badge {
  display: inline-flex; align-items: center; gap: 0.35rem;
  padding: 0.38rem 0.9rem; border-radius: 999px;
  font-size: 0.74rem; font-weight: 700; letter-spacing: 0.03em;
  background: rgba(108,99,255,0.14); border: 1px solid rgba(108,99,255,0.35);
  color: var(--primary-light, #9088ff);
}
.lux-badge.gold  { background: rgba(201,162,39,0.13); border-color: rgba(201,162,39,0.45); color: var(--lux-gold-light); }
.lux-badge.green { background: rgba(0,212,170,0.1);  border-color: rgba(0,212,170,0.32);  color: var(--secondary); }

/* Hero title */
.lux-title {
  display: flex; flex-direction: column; align-items: center;
  font-size: clamp(2rem, 5.5vw, 3.6rem); font-weight: 800; line-height: 1.12;
  margin-bottom: 1.6rem; gap: 0.08em;
}
.lux-title-line1 { color: var(--text-primary); }
.lux-title-line2 {
  background: linear-gradient(135deg, var(--primary-light, #9088ff), var(--secondary));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
  font-size: 1.18em;
}
.lux-title-line3 {
  background: linear-gradient(135deg, var(--lux-gold), var(--lux-gold-light));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
  font-size: 0.78em; letter-spacing: -0.01em;
}

/* Hero subtitle */
.lux-subtitle {
  font-size: clamp(0.94rem, 2vw, 1.08rem); color: var(--text-muted);
  max-width: 720px; margin: 0 auto 2.2rem; line-height: 1.75;
}
.lux-subtitle strong { color: var(--text-primary); }

/* CTA buttons */
.lux-cta-group { display: flex; gap: 0.9rem; justify-content: center; flex-wrap: wrap; margin-bottom: 2.2rem; }
.btn-lux-primary {
  position: relative; overflow: hidden;
  display: inline-flex; align-items: center; gap: 0.5rem;
  padding: 0.95rem 2.3rem; border-radius: 12px; border: none; cursor: pointer;
  font-size: 1rem; font-weight: 700; letter-spacing: 0.02em;
  background: linear-gradient(135deg, #6C63FF 0%, #8B5CF6 50%, #C9A227 100%);
  background-size: 200% auto; color: #fff;
  box-shadow: 0 0 32px rgba(108,99,255,0.4), 0 5px 22px rgba(0,0,0,0.3);
  transition: transform 0.25s, box-shadow 0.25s;
  animation: gradShift 5s ease infinite;
}
@keyframes gradShift { 0%,100%{background-position:0% 50%} 50%{background-position:100% 50%} }
.btn-lux-primary:hover { transform: translateY(-2px); box-shadow: 0 0 50px rgba(108,99,255,0.55), 0 8px 32px rgba(0,0,0,0.35); }
.btn-glow {
  position: absolute; inset: -2px; border-radius: 14px; z-index: -1;
  background: linear-gradient(135deg, rgba(201,162,39,0.3), rgba(108,99,255,0.3));
  filter: blur(10px); animation: glowPulse 2.5s ease-in-out infinite;
}
@keyframes glowPulse { 0%,100%{opacity:0.45} 50%{opacity:1} }
.btn-lux-outline {
  display: inline-flex; align-items: center; gap: 0.5rem;
  padding: 0.95rem 2.3rem; border-radius: 12px;
  border: 1px solid rgba(108,99,255,0.38); font-size: 1rem; font-weight: 600;
  color: var(--primary-light, #9088ff);
  background: rgba(108,99,255,0.07); text-decoration: none;
  transition: all 0.25s;
}
.btn-lux-outline:hover { background: rgba(108,99,255,0.15); border-color: rgba(108,99,255,0.6); transform: translateY(-1px); }
.btn-lux-xl { font-size: 1.1rem; padding: 1.1rem 2.8rem; }

/* Proof row */
.lux-proof-row {
  display: flex; align-items: center; justify-content: center;
  gap: 1.5rem; flex-wrap: wrap; margin-bottom: 2.75rem;
  font-size: 0.875rem; color: var(--text-muted);
}
.lux-proof-item { display: flex; align-items: center; gap: 0.4rem; }
.lux-proof-item strong { color: var(--text-primary); }
.lux-proof-stars { color: #FFD700; font-size: 1rem; letter-spacing: 0.05em; }
.lux-divider-v { width: 1px; height: 18px; background: rgba(255,255,255,0.12); }

/* Stats row */
.lux-stats-row {
  display: flex; justify-content: center; flex-wrap: wrap; gap: 1px;
  background: rgba(108,99,255,0.12); border: 1px solid rgba(108,99,255,0.18);
  border-radius: 16px; overflow: hidden; max-width: 780px; margin: 0 auto;
}
.lux-stat { flex: 1; min-width: 110px; padding: 1.15rem 0.75rem; text-align: center; background: rgba(13,15,26,0.8); }
.lux-stat-num {
  font-size: 1.8rem; font-weight: 800;
  background: linear-gradient(135deg, var(--primary-light, #9088ff), var(--lux-gold-light));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
}
.lux-stat-label { font-size: 0.71rem; color: var(--text-muted); margin-top: 0.25rem; }

/* ── LUX SECTIONS ──────────────────────────────────────── */
.lux-section { padding: 4.5rem 0; border-top: 1px solid rgba(255,255,255,0.05); }
.lux-section-label {
  font-size: 0.68rem; font-weight: 800; letter-spacing: 0.18em;
  text-transform: uppercase; color: var(--lux-gold); margin-bottom: 0.8rem;
}
.lux-section-title {
  font-size: clamp(1.65rem, 3.5vw, 2.3rem); font-weight: 800;
  line-height: 1.2; margin-bottom: 0.9rem; color: var(--text-primary);
}
.lux-section-sub {
  font-size: 0.95rem; color: var(--text-muted); max-width: 660px;
  line-height: 1.72; margin-bottom: 2.75rem;
}

/* ── PAIN GRID ─────────────────────────────────────────── */
.pain-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1rem; }
.pain-card {
  background: var(--bg-card); border: 1px solid rgba(255,255,255,0.07);
  border-radius: 16px; padding: 1.6rem; transition: transform 0.22s, border-color 0.22s;
}
.pain-card:hover { transform: translateY(-3px); border-color: rgba(255,255,255,0.14); }
.pain-card-solution {
  border-color: rgba(201,162,39,0.35);
  background: linear-gradient(135deg, rgba(201,162,39,0.07), rgba(108,99,255,0.04));
}
.pain-card-solution:hover { border-color: rgba(201,162,39,0.6); box-shadow: 0 6px 30px rgba(201,162,39,0.1); }
.pain-icon { font-size: 2.1rem; margin-bottom: 0.8rem; }
.pain-card h4 { font-size: 1rem; font-weight: 700; margin-bottom: 0.55rem; color: var(--text-primary); }
.pain-card p  { font-size: 0.875rem; color: var(--text-muted); line-height: 1.65; margin: 0; }
.pain-solution-tag { margin-top: 0.9rem; font-size: 0.78rem; font-weight: 700; color: var(--lux-gold-light); }

/* ── TRANSFORMATION ────────────────────────────────────── */
.transform-grid { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 1rem; }
@media (max-width: 680px) { .transform-grid { grid-template-columns: 1fr; } .transform-arrow { font-size: 1.5rem; transform: rotate(90deg); text-align: center; } }
.transform-card { border-radius: 16px; padding: 1.85rem; border: 1px solid; }
.transform-card.before { background: rgba(255,60,60,0.04);   border-color: rgba(255,80,80,0.2); }
.transform-card.after  { background: rgba(0,212,170,0.04);   border-color: rgba(0,212,170,0.25); }
.transform-label { font-size: 0.74rem; font-weight: 800; letter-spacing: 0.1em; margin-bottom: 1rem; }
.transform-card.before .transform-label { color: #FF6B6B; }
.transform-card.after  .transform-label { color: var(--secondary); }
.transform-list { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 0.65rem; }
.transform-list li { font-size: 0.875rem; color: var(--text-muted); line-height: 1.5; }
.transform-card.before .transform-list li::before { content: '✗  '; color: #FF6B6B; }
.transform-card.after  .transform-list li::before { content: '✓  '; color: var(--secondary); }
.transform-arrow { font-size: 2.2rem; color: var(--lux-gold); text-align: center; font-weight: 900; }

/* ── INCOME GRID ───────────────────────────────────────── */
.income-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 1rem; }
.income-card {
  position: relative; background: var(--bg-card);
  border: 1px solid rgba(255,255,255,0.07); border-radius: 16px; padding: 1.6rem;
  transition: transform 0.22s, border-color 0.22s;
}
.income-card:hover { transform: translateY(-4px); border-color: rgba(108,99,255,0.3); }
.income-card-featured {
  border-color: rgba(201,162,39,0.38);
  background: linear-gradient(135deg, rgba(201,162,39,0.07), rgba(108,99,255,0.04));
  box-shadow: 0 4px 32px rgba(201,162,39,0.1);
}
.income-card-featured:hover { border-color: rgba(201,162,39,0.65); }
.income-badge-top {
  position: absolute; top: -11px; left: 50%; transform: translateX(-50%);
  background: linear-gradient(135deg, var(--lux-gold), var(--lux-gold-light));
  color: #000; font-size: 0.69rem; font-weight: 800; padding: 0.22rem 0.8rem;
  border-radius: 999px; white-space: nowrap; letter-spacing: 0.05em;
}
.income-icon  { font-size: 2rem; margin-bottom: 0.8rem; }
.income-title { font-size: 1rem; font-weight: 700; color: var(--text-primary); margin-bottom: 0.35rem; }
.income-earn  {
  font-size: 0.84rem; font-weight: 800; margin-bottom: 0.7rem;
  background: linear-gradient(135deg, var(--lux-gold), var(--lux-gold-light));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
}
.income-card p { font-size: 0.82rem; color: var(--text-muted); line-height: 1.65; margin: 0; }

/* ── BUILD GRID ────────────────────────────────────────── */
.build-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(210px, 1fr)); gap: 0.9rem; }
.build-item {
  background: var(--bg-card); border: 1px solid rgba(255,255,255,0.06);
  border-radius: 14px; padding: 1.3rem; display: flex; flex-direction: column; gap: 0.45rem;
  transition: all 0.22s;
}
.build-item:hover { border-color: rgba(108,99,255,0.3); transform: translateY(-2px); box-shadow: 0 6px 24px rgba(108,99,255,0.08); }
.build-icon { font-size: 1.8rem; }
.build-name  { font-size: 0.95rem; font-weight: 700; color: var(--text-primary); }
.build-desc  { font-size: 0.78rem; color: var(--text-muted); line-height: 1.55; }

/* ── SKILL SHOWCASE ────────────────────────────────────── */
.skill-showcase-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 1rem; }
.skill-showcase-card {
  background: var(--bg-card); border: 1px solid rgba(255,255,255,0.07);
  border-radius: 16px; padding: 1.6rem; position: relative; overflow: hidden;
  transition: all 0.22s;
}
.skill-showcase-card:hover { transform: translateY(-3px); border-color: rgba(108,99,255,0.3); }
.skill-showcase-card-featured {
  border-color: rgba(201,162,39,0.3);
  background: linear-gradient(135deg, rgba(201,162,39,0.07), rgba(108,99,255,0.04));
}
.skill-num { position: absolute; top: 0.85rem; right: 1rem; font-size: 2.2rem; font-weight: 900; opacity: 0.07; color: var(--primary); line-height: 1; }
.skill-ico { font-size: 1.8rem; margin-bottom: 0.7rem; }
.skill-showcase-card h4 { font-size: 1rem; font-weight: 700; margin-bottom: 0.5rem; color: var(--text-primary); }
.skill-showcase-card p  { font-size: 0.82rem; color: var(--text-muted); line-height: 1.65; margin: 0; }

/* ── TARGET AUDIENCE ───────────────────────────────────── */
.target-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1rem; }
.target-card {
  background: var(--bg-card); border: 1px solid rgba(255,255,255,0.07);
  border-radius: 16px; padding: 1.6rem; transition: all 0.22s;
}
.target-card:hover { transform: translateY(-3px); border-color: rgba(0,212,170,0.3); box-shadow: 0 6px 24px rgba(0,212,170,0.06); }
.target-icon { font-size: 2rem; margin-bottom: 0.7rem; }
.target-card h4 { font-size: 1rem; font-weight: 700; color: var(--text-primary); margin-bottom: 0.5rem; }
.target-card p  { font-size: 0.82rem; color: var(--text-muted); line-height: 1.65; margin: 0 0 0.9rem; }
.target-tag {
  display: inline-block; font-size: 0.71rem; font-weight: 700;
  color: var(--secondary); border: 1px solid rgba(0,212,170,0.3);
  background: rgba(0,212,170,0.08); padding: 0.22rem 0.65rem; border-radius: 999px;
}

/* ── CURRICULUM TIMELINE ───────────────────────────────── */
.curriculum-timeline { display: flex; flex-direction: column; gap: 1.25rem; }
.ct-phase { border-radius: 16px; overflow: hidden; border: 1px solid rgba(255,255,255,0.07); }
.ct-phase-header { display: flex; align-items: center; gap: 1rem; padding: 1.1rem 1.5rem; flex-wrap: wrap; }
.ct-phase-1 .ct-phase-header { background: rgba(108,99,255,0.13); }
.ct-phase-2 .ct-phase-header { background: rgba(0,212,170,0.1);   }
.ct-phase-3 .ct-phase-header { background: rgba(59,130,246,0.1);  }
.ct-phase-4 .ct-phase-header { background: rgba(201,162,39,0.1);  }
.ct-phase-num {
  font-size: 0.68rem; font-weight: 800; letter-spacing: 0.12em; text-transform: uppercase;
  padding: 0.25rem 0.7rem; border-radius: 999px; white-space: nowrap;
}
.ct-phase-1 .ct-phase-num { background: rgba(108,99,255,0.28); color: var(--primary-light, #9088ff); }
.ct-phase-2 .ct-phase-num { background: rgba(0,212,170,0.2);   color: var(--secondary);             }
.ct-phase-3 .ct-phase-num { background: rgba(59,130,246,0.25); color: #60A5FA;                      }
.ct-phase-4 .ct-phase-num { background: rgba(201,162,39,0.25); color: var(--lux-gold-light);        }
.ct-phase-title { font-size: 1rem; font-weight: 700; color: var(--text-primary); flex: 1; }
.ct-phase-time  { font-size: 0.8rem; color: var(--text-muted); }
.ct-chapters { padding: 0.8rem; display: flex; flex-direction: column; gap: 0.5rem; background: var(--bg-card); }
.ct-chapter {
  display: flex; align-items: flex-start; gap: 1rem;
  padding: 0.9rem 1rem; border-radius: 10px; text-decoration: none; color: inherit;
  background: rgba(255,255,255,0.03); border: 1px solid rgba(255,255,255,0.05);
  transition: all 0.18s;
}
.ct-chapter:hover { background: rgba(108,99,255,0.08); border-color: rgba(108,99,255,0.25); }
.ct-chapter-bonus { border-color: rgba(201,162,39,0.2); background: rgba(201,162,39,0.04); }
.ct-chapter-bonus:hover { border-color: rgba(201,162,39,0.4); background: rgba(201,162,39,0.08); }
.ct-ch-num {
  min-width: 48px; padding: 0.22rem 0.45rem; border-radius: 7px;
  font-size: 0.7rem; font-weight: 700; text-align: center;
  background: rgba(108,99,255,0.2); color: var(--primary-light, #9088ff); flex-shrink: 0;
}
.ct-chapter-bonus .ct-ch-num { background: rgba(201,162,39,0.2); color: var(--lux-gold-light); }
.ct-ch-title { font-size: 0.9rem; font-weight: 600; color: var(--text-primary); margin-bottom: 0.2rem; }
.ct-ch-desc  { font-size: 0.775rem; color: var(--text-muted); line-height: 1.45; }
.ct-ch-time  { font-size: 0.75rem; color: var(--text-muted); white-space: nowrap; margin-left: auto; padding-top: 0.1rem; flex-shrink: 0; }

/* ── FAQ ───────────────────────────────────────────────── */
.faq-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1rem; }
.faq-card {
  background: var(--bg-card); border: 1px solid rgba(255,255,255,0.07);
  border-radius: 14px; padding: 1.4rem; transition: all 0.22s;
}
.faq-card:hover { border-color: rgba(108,99,255,0.25); transform: translateY(-2px); }
.faq-q { font-size: 0.925rem; font-weight: 700; color: var(--text-primary); margin-bottom: 0.7rem; }
.faq-card p { font-size: 0.82rem; color: var(--text-muted); line-height: 1.68; margin: 0; }

/* ── AUTHOR LUXURY ─────────────────────────────────────── */
.author-lux-card {
  display: flex; gap: 2rem; align-items: flex-start; flex-wrap: wrap;
  background: linear-gradient(135deg, rgba(108,99,255,0.08), rgba(201,162,39,0.04));
  border: 1px solid rgba(108,99,255,0.2); border-radius: 20px; padding: 2.25rem;
}
.author-lux-avatar {
  width: 82px; height: 82px; border-radius: 50%; flex-shrink: 0;
  background: linear-gradient(135deg, var(--primary), var(--lux-gold));
  display: flex; align-items: center; justify-content: center;
  font-size: 2.1rem; font-weight: 800; color: #fff;
  box-shadow: 0 0 28px rgba(108,99,255,0.35);
}
.author-lux-body { flex: 1; min-width: 220px; }
.author-lux-name { font-size: 1.25rem; font-weight: 800; color: var(--text-primary); margin-bottom: 0.2rem; }
.author-lux-role { font-size: 0.82rem; font-weight: 700; color: var(--lux-gold); margin-bottom: 0.85rem; }
.author-lux-bio  { font-size: 0.875rem; color: var(--text-muted); line-height: 1.72; margin-bottom: 1rem; }
.author-lux-bio em { color: var(--text-primary); font-style: italic; }

/* ── FINAL CTA ─────────────────────────────────────────── */
.lux-final-cta {
  margin-left: -2.5rem;
  margin-right: -2.5rem;
  position: relative; overflow: hidden; text-align: center;
  padding: 5.5rem 1.5rem; margin-top: 2rem; border-radius: 20px;
  background: linear-gradient(135deg, rgba(108,99,255,0.1), rgba(201,162,39,0.06), rgba(0,212,170,0.05));
  border: 1px solid rgba(108,99,255,0.2);
}
.lux-orb-cta-1 { width: 380px; height: 380px; background: rgba(108,99,255,0.13); top: -110px; left: -110px; animation: orbFloat 7s ease-in-out infinite; }
.lux-orb-cta-2 { width: 260px; height: 260px; background: rgba(201,162,39,0.09); bottom: -70px; right: -70px; animation: orbFloat 9s ease-in-out infinite reverse; }
.lux-final-cta-inner { position: relative; z-index: 1; max-width: 720px; margin: 0 auto; }
.lux-final-badge {
  display: inline-block; font-size: 0.74rem; font-weight: 800; letter-spacing: 0.12em;
  padding: 0.38rem 1.1rem; border-radius: 999px; margin-bottom: 1.4rem;
  background: rgba(201,162,39,0.15); border: 1px solid rgba(201,162,39,0.38);
  color: var(--lux-gold-light); text-transform: uppercase;
}
.lux-final-title {
  font-size: clamp(1.65rem, 3.5vw, 2.6rem); font-weight: 800; line-height: 1.2;
  margin-bottom: 1.1rem; color: var(--text-primary);
}
.lux-final-sub { font-size: 0.95rem; color: var(--text-muted); line-height: 1.75; max-width: 580px; margin: 0 auto 2.25rem; }
.lux-final-cta-group { margin-bottom: 1.1rem; }
.lux-final-note { font-size: 0.82rem; color: var(--text-muted); margin-bottom: 1.4rem; }
.lux-link { color: var(--secondary); text-decoration: none; }
.lux-link:hover { text-decoration: underline; }
.lux-final-guarantee {
  display: flex; align-items: center; justify-content: center;
  gap: 0.8rem; flex-wrap: wrap; font-size: 0.78rem; color: var(--text-muted);
}


/* ─── Payment Modal: EBOOK badge + QR + roadmap sub ──── */
.pay-ebook-badge {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  background: rgba(108,99,255,.15);
  border: 1px solid rgba(108,99,255,.35);
  color: #A09CF8;
  font-size: .78rem;
  font-weight: 600;
  padding: .35rem .85rem;
  border-radius: 20px;
  margin-bottom: .85rem;
  letter-spacing: .02em;
}
.pay-roadmap-title {
  font-size: .82rem;
  font-weight: 700;
  color: var(--text-muted);
  letter-spacing: .08em;
  text-transform: uppercase;
  margin: .75rem 0 .45rem;
}
.pay-roadmap-sub {
  font-size: .75rem;
  color: var(--text-muted);
  margin-top: .2rem;
  line-height: 1.5;
}
.pay-roadmap-bonus {
  border-color: rgba(201,162,39,.3);
  background: rgba(201,162,39,.05);
}
/* QR code */
.pay-qr-wrap {
  text-align: center;
  margin-bottom: .85rem;
}
.pay-qr-label {
  font-size: .78rem;
  color: var(--text-muted);
  margin-bottom: .4rem;
  font-weight: 500;
}
.pay-qr-img {
  max-width: 200px;
  width: 100%;
  border-radius: 12px;
  border: 2px solid rgba(108,99,255,.25);
  display: block;
  margin: 0 auto;
}
/* User form in payment tab */
.pay-user-form {
  margin-bottom: .85rem;
}

/* ═══════════════════════════════════════════════════════════
   BOOK-STYLE CONTENT ELEMENTS — ThanhDoIT Giáo Trình AI
═══════════════════════════════════════════════════════════ */

/* ─── Prompt Box (AI Prompt mẫu) ─── */
.prompt-box {
  background: rgba(108,99,255,.09);
  border-left: 4px solid var(--primary);
  border-radius: 0 10px 10px 0;
  padding: 1.1rem 1.35rem;
  margin: 1.35rem 0;
  position: relative;
}
.prompt-box::before {
  content: '🤖  Prompt Mẫu — Copy & dùng ngay';
  display: block;
  font-size: .67rem;
  font-weight: 700;
  color: #A09CF8;
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-bottom: .65rem;
}
.prompt-box pre {
  margin: 0;
  background: rgba(0,0,0,.35) !important;
  padding: .85rem 1rem !important;
  border-radius: 7px;
  font-size: .8rem;
  line-height: 1.7;
  white-space: pre-wrap;
  word-break: break-word;
}
.prompt-box .prompt-note {
  font-size: .74rem;
  color: var(--text-muted);
  margin-top: .6rem;
  font-style: italic;
}

/* ─── Tip Box (Mẹo Thông Minh) ─── */
.tip-box {
  background: rgba(0,212,170,.07);
  border-left: 4px solid var(--secondary);
  border-radius: 0 10px 10px 0;
  padding: 1rem 1.35rem;
  margin: 1.25rem 0;
}
.tip-box::before {
  content: '💡  Mẹo Thông Minh';
  display: block;
  font-size: .67rem;
  font-weight: 700;
  color: var(--secondary);
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-bottom: .5rem;
}
.tip-box p { margin: 0; font-size: .85rem; line-height: 1.65; }

/* ─── Practice Box (Thực Hành) ─── */
.practice-box {
  background: rgba(240,192,64,.07);
  border: 1px solid rgba(240,192,64,.22);
  border-radius: 10px;
  padding: 1.1rem 1.35rem;
  margin: 1.35rem 0;
}
.practice-box::before {
  content: '🎯  Thực Hành Ngay';
  display: block;
  font-size: .67rem;
  font-weight: 700;
  color: #F0C040;
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-bottom: .5rem;
}
.practice-box ol,.practice-box ul { margin: 0; padding-left: 1.25rem; }
.practice-box li { font-size: .84rem; line-height: 1.7; }

/* ─── Warning Box ─── */
.warning-box {
  background: rgba(255,107,107,.07);
  border-left: 4px solid #FF6B6B;
  border-radius: 0 10px 10px 0;
  padding: 1rem 1.35rem;
  margin: 1.25rem 0;
}
.warning-box::before {
  content: '⚠  Lưu Ý Quan Trọng';
  display: block;
  font-size: .67rem;
  font-weight: 700;
  color: #FF6B6B;
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-bottom: .5rem;
}
.warning-box p { margin: 0; font-size: .85rem; line-height: 1.6; }

/* ─── Info Box ─── */
.info-box {
  background: rgba(100,200,255,.07);
  border-left: 4px solid #64C8FF;
  border-radius: 0 10px 10px 0;
  padding: 1rem 1.35rem;
  margin: 1.25rem 0;
}
.info-box::before {
  content: 'ℹ  Thông Tin';
  display: block;
  font-size: .67rem;
  font-weight: 700;
  color: #64C8FF;
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-bottom: .5rem;
}
.info-box p { margin: 0; font-size: .85rem; line-height: 1.6; }

/* ─── Success Box ─── */
.success-box {
  background: rgba(0,212,100,.07);
  border-left: 4px solid #00D464;
  border-radius: 0 10px 10px 0;
  padding: 1rem 1.35rem;
  margin: 1.25rem 0;
}
.success-box::before {
  content: '✅  Kết Quả Mong Đợi';
  display: block;
  font-size: .67rem;
  font-weight: 700;
  color: #00D464;
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-bottom: .5rem;
}

/* ─── Step-by-Step Grid ─── */
.step-grid { display: grid; gap: .85rem; margin: 1.25rem 0; }
.step-item {
  background: var(--bg-card);
  border: 1px solid rgba(255,255,255,.06);
  border-radius: 10px;
  padding: 1rem 1.2rem;
  display: flex;
  gap: 1rem;
  align-items: flex-start;
}
.step-item:hover { border-color: rgba(108,99,255,.3); }
.step-num {
  background: var(--primary);
  color: #fff;
  font-weight: 800;
  font-size: .75rem;
  width: 28px; height: 28px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
}
.step-num.green { background: var(--secondary); }
.step-num.gold { background: #C9A227; }
.step-content strong { display: block; margin-bottom: .22rem; font-size: .9rem; }
.step-content p,.step-content span { font-size: .81rem; color: var(--text-muted); margin: 0; line-height: 1.55; }

/* ─── Quick Reference Table ─── */
.quick-table { width: 100%; border-collapse: collapse; font-size: .81rem; margin: 1rem 0; }
.quick-table th {
  background: rgba(108,99,255,.12);
  color: #A09CF8;
  font-weight: 700;
  padding: .6rem .9rem;
  text-align: left;
  font-size: .72rem;
  text-transform: uppercase;
  letter-spacing: .06em;
}
.quick-table td {
  padding: .6rem .9rem;
  border-bottom: 1px solid rgba(255,255,255,.05);
  vertical-align: top;
  line-height: 1.5;
}
.quick-table tr:hover td { background: rgba(255,255,255,.02); }
.quick-table code {
  background: rgba(108,99,255,.15);
  padding: .13rem .38rem;
  border-radius: 4px;
  font-size: .78rem;
}
.quick-table .tag-green {
  background: rgba(0,212,170,.15);
  color: var(--secondary);
  padding: .1rem .45rem;
  border-radius: 20px;
  font-size: .7rem;
  font-weight: 600;
}
.quick-table .tag-orange {
  background: rgba(240,192,64,.15);
  color: #F0C040;
  padding: .1rem .45rem;
  border-radius: 20px;
  font-size: .7rem;
  font-weight: 600;
}

/* ─── Chapter Overview Card ─── */
.chapter-overview {
  background: linear-gradient(135deg,rgba(108,99,255,.1),rgba(0,212,170,.06));
  border: 1px solid rgba(108,99,255,.2);
  border-radius: 12px;
  padding: 1.25rem 1.5rem;
  margin: 1.25rem 0;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}
@media(max-width:600px){.chapter-overview{grid-template-columns:1fr}}
.chapter-overview h4 { color: var(--primary); font-size: .9rem; margin: 0 0 .6rem; }
.chapter-overview ul { margin: 0; padding-left: 1.2rem; }
.chapter-overview li { font-size: .82rem; line-height: 1.7; color: var(--text-muted); }

/* ─── Command Card ─── */
.cmd-card {
  background: var(--bg-card);
  border: 1px solid rgba(255,255,255,.07);
  border-radius: 10px;
  padding: 1rem 1.2rem;
  margin-bottom: .75rem;
}
.cmd-card:hover { border-color: rgba(108,99,255,.3); }
.cmd-card .cmd-title { font-weight: 700; font-size: .88rem; margin-bottom: .35rem; }
.cmd-card .cmd-title .cmd-tag {
  font-size: .65rem;
  font-weight: 700;
  padding: .1rem .4rem;
  border-radius: 4px;
  margin-left: .4rem;
  vertical-align: middle;
}
.cmd-tag-chat { background: rgba(108,99,255,.25); color: #A09CF8; }
.cmd-tag-terminal { background: rgba(0,212,170,.2); color: var(--secondary); }
.cmd-tag-inline { background: rgba(240,192,64,.2); color: #F0C040; }
.cmd-card .cmd-desc { font-size: .78rem; color: var(--text-muted); margin-bottom: .65rem; line-height: 1.5; }
.cmd-card pre { margin: 0; font-size: .77rem; }

/* ─── Build Template Card ─── */
.build-template {
  background: var(--bg-card);
  border: 1px solid rgba(255,255,255,.07);
  border-radius: 12px;
  overflow: hidden;
  margin-bottom: 1.5rem;
}
.build-template .bt-header {
  padding: 1rem 1.3rem;
  background: rgba(108,99,255,.1);
  border-bottom: 1px solid rgba(108,99,255,.2);
  display: flex; align-items: center; gap: .75rem;
}
.build-template .bt-icon { font-size: 1.4rem; }
.build-template .bt-title { font-weight: 700; font-size: 1rem; }
.build-template .bt-tech { font-size: .75rem; color: var(--text-muted); margin-top: .1rem; }
.build-template .bt-body { padding: 1.1rem 1.3rem; }
.build-template .bt-body pre { font-size: .77rem; margin: .5rem 0; }

/* ─── Selenium specific ─── */
.selenium-badge {
  display: inline-flex; align-items: center; gap: .4rem;
  background: rgba(255,107,107,.12);
  border: 1px solid rgba(255,107,107,.25);
  color: #FF8C8C;
  font-size: .72rem; font-weight: 700;
  padding: .25rem .7rem; border-radius: 20px;
  margin-bottom: .5rem;
}
.locator-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: .75rem; margin: 1rem 0;
}
@media(max-width:600px){.locator-grid{grid-template-columns:1fr}}
.locator-card {
  background: var(--bg-card);
  border: 1px solid rgba(255,255,255,.06);
  border-radius: 8px; padding: .8rem 1rem;
}
.locator-card .lc-name { font-weight: 700; font-size: .82rem; color: var(--primary); margin-bottom: .25rem; }
.locator-card .lc-example { font-size: .74rem; font-family: 'JetBrains Mono',monospace; color: var(--secondary); }
.locator-card .lc-use { font-size: .73rem; color: var(--text-muted); margin-top: .2rem; }


/* ================================================
   FLOATING CONTACT BUTTON (Zalo / Phone)
   ================================================ */
.float-contact {
  position: fixed;
  bottom: 2rem;
  right: 1.5rem;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.6rem;
}

.float-contact-btn {
  position: relative;
  width: 52px;
  height: 52px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  box-shadow: 0 4px 20px rgba(0,0,0,0.4);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  cursor: pointer;
  border: 2px solid rgba(255,255,255,0.15);
}

.float-contact-btn:hover {
  transform: scale(1.12);
  box-shadow: 0 6px 28px rgba(0,0,0,0.55);
}

.float-contact-btn svg {
  width: 26px;
  height: 26px;
  flex-shrink: 0;
}

/* Zalo button */
.float-zalo {
  background: #0068FF;
}

/* Phone button */
.float-phone {
  background: #00C853;
}

/* Tooltip */
.float-contact-btn .float-tooltip {
  position: absolute;
  right: calc(100% + 10px);
  top: 50%;
  transform: translateY(-50%);
  background: rgba(15, 18, 35, 0.95);
  color: #E8EAFB;
  font-size: 0.72rem;
  font-weight: 600;
  white-space: nowrap;
  padding: 0.3rem 0.65rem;
  border-radius: 6px;
  border: 1px solid rgba(255,255,255,0.1);
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.2s ease;
}

.float-contact-btn:hover .float-tooltip {
  opacity: 1;
}

/* Pulse ring animation for Zalo */
.float-zalo::after {
  content: '';
  position: absolute;
  inset: -4px;
  border-radius: 50%;
  border: 2px solid #0068FF;
  animation: float-pulse 2s ease-out infinite;
  opacity: 0;
}

@keyframes float-pulse {
  0%   { transform: scale(1); opacity: 0.7; }
  100% { transform: scale(1.6); opacity: 0; }
}

@media (max-width: 480px) {
  .float-contact {
    bottom: 1.25rem;
    right: 1rem;
  }
  .float-contact-btn {
    width: 46px;
    height: 46px;
  }
}