/* ============================================
   Bustan Energy Academy — Design System
   Colors: Navy #0A1628, Green #00D68F, Gold #FFB800
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=Heebo:wght@300;400;500;600;700;800;900&family=Noto+Sans+Thai:wght@300;400;500;600;700;800;900&display=swap');

:root {
  --navy: #0A1628;
  --navy-light: #111D31;
  --navy-lighter: #162440;
  --navy-card: #0D1B30;
  --green: #00D68F;
  --green-dim: #00B377;
  --green-glow: rgba(0, 214, 143, 0.15);
  --gold: #FFB800;
  --gold-dim: #E6A600;
  --gold-glow: rgba(255, 184, 0, 0.15);
  --text-primary: #F0F4F8;
  --text-secondary: #8899AA;
  --text-dim: #5A6B7D;
  --glass-bg: rgba(13, 27, 48, 0.7);
  --glass-border: rgba(255, 255, 255, 0.06);
  --glass-border-hover: rgba(0, 214, 143, 0.2);
  --radius: 16px;
  --radius-sm: 10px;
  --radius-xs: 6px;
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 16px 48px rgba(0, 0, 0, 0.4);
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', 'Heebo', 'Noto Sans Thai', sans-serif;
  background: var(--navy);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
  overflow-x: hidden;
}

body[data-lang="he"] { direction: rtl; font-family: 'Heebo', 'Inter', sans-serif; }
body[data-lang="th"] { font-family: 'Noto Sans Thai', 'Inter', sans-serif; }
body[data-lang="en"] { font-family: 'Inter', sans-serif; }

/* ---- Background Ambient ---- */
.bg-ambient {
  position: fixed; inset: 0; z-index: 0; pointer-events: none;
  background:
    radial-gradient(ellipse 600px 400px at 15% 20%, rgba(0,214,143,0.06), transparent),
    radial-gradient(ellipse 500px 500px at 85% 70%, rgba(255,184,0,0.04), transparent),
    radial-gradient(ellipse 800px 600px at 50% 50%, rgba(10,22,40,1), transparent);
}

/* ---- Header ---- */
.header {
  position: sticky; top: 0; z-index: 100;
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  background: rgba(10, 22, 40, 0.85);
  border-bottom: 1px solid var(--glass-border);
  padding: 0 2rem;
}
.header-inner {
  max-width: 1280px; margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between;
  height: 64px;
}
.header-logo {
  display: flex; align-items: center; gap: 12px;
  text-decoration: none; color: var(--text-primary);
}
.header-logo img { height: 36px; width: auto; }
.header-logo span { font-weight: 700; font-size: 1.1rem; letter-spacing: -0.02em; }
.header-nav { display: flex; align-items: center; gap: 8px; }

.lang-toggle {
  display: flex; gap: 2px;
  background: var(--navy-lighter); border-radius: 8px; padding: 3px;
}
.lang-btn {
  background: none; border: none; color: var(--text-secondary);
  padding: 6px 14px; border-radius: 6px; cursor: pointer;
  font-size: 0.85rem; font-weight: 500; transition: var(--transition);
}
.lang-btn.active {
  background: var(--green); color: var(--navy); font-weight: 700;
}
.lang-btn:hover:not(.active) { color: var(--text-primary); }

/* ---- Main Content ---- */
.main { position: relative; z-index: 1; }

/* ---- Hero ---- */
.hero {
  text-align: center; padding: 5rem 2rem 3rem;
  max-width: 900px; margin: 0 auto;
}
.hero-badge {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--green-glow); border: 1px solid rgba(0,214,143,0.2);
  padding: 6px 18px; border-radius: 100px; font-size: 0.85rem;
  color: var(--green); font-weight: 500; margin-bottom: 1.5rem;
}
.hero-badge::before { content: ''; width: 6px; height: 6px; background: var(--green); border-radius: 50%; animation: pulse-dot 2s infinite; }
@keyframes pulse-dot {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(1.5); }
}
.hero h1 {
  font-size: clamp(2.5rem, 5vw, 3.8rem);
  font-weight: 900; letter-spacing: -0.03em;
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--green) 50%, var(--gold) 100%);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text; margin-bottom: 1rem;
  line-height: 1.15;
}
.hero-subtitle {
  font-size: 1.15rem; color: var(--text-secondary);
  max-width: 640px; margin: 0 auto 2rem; line-height: 1.8;
}

/* ---- Glass Card ---- */
.glass-card {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition: var(--transition);
  overflow: hidden;
}
.glass-card:hover {
  border-color: var(--glass-border-hover);
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg), 0 0 40px var(--green-glow);
}

/* ---- Tracks Grid ---- */
.tracks-section { padding: 2rem 2rem 4rem; max-width: 1280px; margin: 0 auto; }
.section-label {
  text-transform: uppercase; font-size: 0.8rem; letter-spacing: 0.15em;
  color: var(--green); font-weight: 600; margin-bottom: 0.5rem;
}
.section-title {
  font-size: 1.8rem; font-weight: 800; margin-bottom: 2rem;
  letter-spacing: -0.02em;
}
.tracks-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 1.5rem;
}
.track-card { padding: 2rem; cursor: pointer; text-decoration: none; display: block; position: relative; }
.track-card::before {
  content: ''; position: absolute; inset: 0; border-radius: var(--radius);
  background: linear-gradient(135deg, transparent 60%, var(--green-glow));
  opacity: 0; transition: var(--transition);
}
.track-card:hover::before { opacity: 1; }
.track-icon { font-size: 2.5rem; margin-bottom: 1rem; display: block; }
.track-title { font-size: 1.25rem; font-weight: 700; margin-bottom: 0.25rem; color: var(--text-primary); }
.track-title-sub { font-size: 0.95rem; color: var(--text-secondary); margin-bottom: 1rem; }
.track-meta {
  display: flex; gap: 1.5rem; font-size: 0.85rem; color: var(--text-dim);
  margin-bottom: 1.25rem;
}
.track-meta span { display: flex; align-items: center; gap: 4px; }
.progress-bar-bg {
  width: 100%; height: 6px; background: var(--navy-lighter);
  border-radius: 3px; overflow: hidden;
}
.progress-bar-fill {
  height: 100%; background: linear-gradient(90deg, var(--green), var(--gold));
  border-radius: 3px; transition: width 0.6s ease; min-width: 0;
}
.progress-label {
  font-size: 0.78rem; color: var(--text-dim); margin-top: 6px;
  display: flex; justify-content: space-between;
}

/* ---- Stats ---- */
.stats-section { padding: 2rem 2rem 4rem; max-width: 1280px; margin: 0 auto; }
.stats-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
}
.stat-card {
  text-align: center; padding: 2rem;
}
.stat-number {
  font-size: 2.8rem; font-weight: 900; color: var(--green);
  line-height: 1; margin-bottom: 0.5rem;
}
.stat-number.gold { color: var(--gold); }
.stat-label { font-size: 0.95rem; color: var(--text-secondary); }

/* ---- Footer ---- */
.footer {
  border-top: 1px solid var(--glass-border);
  padding: 2.5rem 2rem; text-align: center;
  color: var(--text-dim); font-size: 0.85rem;
}
.footer a { color: var(--green); text-decoration: none; }
.footer a:hover { text-decoration: underline; }
.footer-links { display: flex; justify-content: center; gap: 2rem; margin-bottom: 1rem; flex-wrap: wrap; }

/* ---- Animations ---- */
.fade-up {
  opacity: 0; transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-up.visible { opacity: 1; transform: translateY(0); }
.fade-up:nth-child(2) { transition-delay: 0.1s; }
.fade-up:nth-child(3) { transition-delay: 0.2s; }
.fade-up:nth-child(4) { transition-delay: 0.3s; }
.fade-up:nth-child(5) { transition-delay: 0.4s; }

/* ============================================
   Lesson Page Styles
   ============================================ */

.lesson-container { max-width: 860px; margin: 0 auto; padding: 2rem; }

/* Breadcrumb */
.breadcrumb {
  display: flex; align-items: center; gap: 8px;
  font-size: 0.85rem; color: var(--text-dim);
  margin-bottom: 2rem; flex-wrap: wrap;
}
.breadcrumb a { color: var(--green); text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }

/* Lesson Header */
.lesson-header { margin-bottom: 3rem; }
.lesson-number {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--green-glow); border: 1px solid rgba(0,214,143,0.2);
  padding: 5px 16px; border-radius: 100px; font-size: 0.82rem;
  color: var(--green); font-weight: 600; margin-bottom: 1rem;
}
.lesson-title {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: 800; letter-spacing: -0.02em; margin-bottom: 0.75rem;
  line-height: 1.2;
}
.lesson-meta {
  display: flex; gap: 1.5rem; color: var(--text-dim);
  font-size: 0.9rem; flex-wrap: wrap;
}
.lesson-meta span { display: flex; align-items: center; gap: 6px; }

/* Content Sections */
.content-section { margin-bottom: 3rem; }
.content-section h2 {
  font-size: 1.5rem; font-weight: 700; margin-bottom: 1rem;
  color: var(--text-primary); position: relative; padding-left: 16px;
}
body[data-lang="he"] .content-section h2 { padding-left: 0; padding-right: 16px; }
.content-section h2::before {
  content: ''; position: absolute; left: 0; top: 4px;
  width: 4px; height: 24px; background: var(--green); border-radius: 2px;
}
body[data-lang="he"] .content-section h2::before { left: auto; right: 0; }
.content-section h3 {
  font-size: 1.15rem; font-weight: 600; margin: 1.5rem 0 0.75rem;
  color: var(--green);
}
.content-section p { color: var(--text-secondary); margin-bottom: 1rem; }
.content-section ul, .content-section ol {
  color: var(--text-secondary); padding-left: 1.5rem; margin-bottom: 1rem;
}
body[data-lang="he"] .content-section ul,
body[data-lang="he"] .content-section ol { padding-left: 0; padding-right: 1.5rem; }
.content-section li { margin-bottom: 0.4rem; }

/* Key Term Card */
.key-term {
  background: var(--navy-lighter); border-left: 3px solid var(--gold);
  padding: 1.25rem 1.5rem; border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 1.5rem 0;
}
body[data-lang="he"] .key-term {
  border-left: none; border-right: 3px solid var(--gold);
  border-radius: var(--radius-sm) 0 0 var(--radius-sm);
}
.key-term strong { color: var(--gold); }
.key-term p { color: var(--text-secondary); margin: 0; }

/* Did You Know */
.did-you-know {
  background: linear-gradient(135deg, var(--gold-glow), transparent);
  border: 1px solid rgba(255,184,0,0.15);
  border-radius: var(--radius);
  padding: 1.5rem; margin: 1.5rem 0;
  position: relative;
}
.did-you-know::before {
  content: '💡'; position: absolute; top: -12px; left: 16px;
  font-size: 1.3rem; background: var(--navy); padding: 0 8px;
}
body[data-lang="he"] .did-you-know::before { left: auto; right: 16px; }
.did-you-know .dyk-title {
  font-weight: 700; color: var(--gold); margin-bottom: 0.5rem; font-size: 0.9rem;
}
.did-you-know p { color: var(--text-secondary); margin: 0; font-size: 0.95rem; }

/* Diagram Placeholder */
.diagram-placeholder {
  background: var(--navy-lighter); border: 2px dashed var(--glass-border);
  border-radius: var(--radius); padding: 3rem 2rem;
  text-align: center; color: var(--text-dim); margin: 1.5rem 0;
  font-size: 0.9rem;
}
.diagram-placeholder .icon { font-size: 2rem; margin-bottom: 0.5rem; display: block; }

/* Spec Table */
.spec-table {
  width: 100%; border-collapse: collapse; margin: 1.5rem 0;
  font-size: 0.9rem;
}
.spec-table th, .spec-table td {
  padding: 10px 14px; text-align: left;
  border-bottom: 1px solid var(--glass-border);
}
body[data-lang="he"] .spec-table th,
body[data-lang="he"] .spec-table td { text-align: right; }
.spec-table th {
  color: var(--green); font-weight: 600; font-size: 0.82rem;
  text-transform: uppercase; letter-spacing: 0.05em;
}
.spec-table td { color: var(--text-secondary); }
.spec-table tr:hover td { background: rgba(0,214,143,0.03); }

/* Quiz Section */
.quiz-section {
  background: var(--glass-bg); border: 1px solid var(--glass-border);
  border-radius: var(--radius); padding: 2rem; margin-top: 3rem;
}
.quiz-title {
  font-size: 1.3rem; font-weight: 700; margin-bottom: 1.5rem;
  display: flex; align-items: center; gap: 10px;
}
.quiz-question {
  background: var(--navy-lighter); border-radius: var(--radius-sm);
  padding: 1.5rem; margin-bottom: 1.25rem;
}
.quiz-question p {
  font-weight: 600; color: var(--text-primary); margin-bottom: 1rem;
  font-size: 1rem;
}
.quiz-options { display: flex; flex-direction: column; gap: 8px; }
.quiz-option {
  display: flex; align-items: center; gap: 10px;
  background: var(--navy); border: 1px solid var(--glass-border);
  padding: 10px 14px; border-radius: var(--radius-xs);
  cursor: pointer; transition: var(--transition); font-size: 0.92rem;
  color: var(--text-secondary);
}
.quiz-option:hover { border-color: var(--green); color: var(--text-primary); }
.quiz-option.correct {
  border-color: var(--green); background: var(--green-glow);
  color: var(--green); font-weight: 600;
}
.quiz-option.incorrect {
  border-color: #FF4757; background: rgba(255,71,87,0.1);
  color: #FF4757;
}
.quiz-option.disabled { pointer-events: none; opacity: 0.7; }
.quiz-option .marker {
  width: 22px; height: 22px; border-radius: 50%;
  border: 2px solid var(--glass-border); display: flex;
  align-items: center; justify-content: center; flex-shrink: 0;
  font-size: 0.75rem; font-weight: 700;
}
.quiz-option.correct .marker { border-color: var(--green); background: var(--green); color: var(--navy); }
.quiz-option.incorrect .marker { border-color: #FF4757; background: #FF4757; color: #fff; }

.quiz-result {
  margin-top: 1.5rem; padding: 1.25rem; border-radius: var(--radius-sm);
  text-align: center; font-weight: 600; display: none;
}
.quiz-result.show { display: block; }
.quiz-result.pass { background: var(--green-glow); color: var(--green); }
.quiz-result.fail { background: rgba(255,71,87,0.1); color: #FF6B7A; }

/* Lesson Navigation */
.lesson-nav {
  display: flex; justify-content: space-between; align-items: center;
  margin-top: 3rem; padding-top: 2rem;
  border-top: 1px solid var(--glass-border);
  gap: 1rem; flex-wrap: wrap;
}
.lesson-nav a {
  display: flex; align-items: center; gap: 8px;
  color: var(--green); text-decoration: none; font-weight: 600;
  font-size: 0.95rem; padding: 10px 20px;
  border: 1px solid rgba(0,214,143,0.2); border-radius: var(--radius-sm);
  transition: var(--transition);
}
.lesson-nav a:hover { background: var(--green-glow); border-color: var(--green); }
.lesson-nav .nav-center { color: var(--text-dim); font-size: 0.85rem; }

/* Complete Button */
.complete-btn {
  display: flex; align-items: center; justify-content: center; gap: 10px;
  width: 100%; padding: 16px; margin-top: 2rem;
  background: linear-gradient(135deg, var(--green), var(--green-dim));
  color: var(--navy); font-weight: 700; font-size: 1.05rem;
  border: none; border-radius: var(--radius-sm); cursor: pointer;
  transition: var(--transition);
}
.complete-btn:hover { transform: translateY(-2px); box-shadow: 0 8px 24px var(--green-glow); }
.complete-btn.completed {
  background: var(--navy-lighter); color: var(--green);
  border: 1px solid rgba(0,214,143,0.3); cursor: default;
}
.complete-btn.completed:hover { transform: none; box-shadow: none; }

/* ---- Responsive ---- */
@media (max-width: 768px) {
  .header { padding: 0 1rem; }
  .header-inner { height: 56px; }
  .hero { padding: 3rem 1.5rem 2rem; }
  .tracks-grid { grid-template-columns: 1fr; }
  .lesson-container { padding: 1.5rem; }
  .lesson-nav { flex-direction: column; align-items: stretch; text-align: center; }
  .lang-btn { padding: 5px 10px; font-size: 0.8rem; }
}

/* ---- Lang visibility ---- */
[data-en], [data-he], [data-th] { display: none; }
body[data-lang="en"] [data-en] { display: unset; }
body[data-lang="he"] [data-he] { display: unset; }
body[data-lang="th"] [data-th] { display: unset; }

/* Block-level lang elements */
div[data-en], div[data-he], div[data-th],
p[data-en], p[data-he], p[data-th],
h1[data-en], h1[data-he], h1[data-th],
h2[data-en], h2[data-he], h2[data-th],
h3[data-en], h3[data-he], h3[data-th],
li[data-en], li[data-he], li[data-th],
section[data-en], section[data-he], section[data-th] {
  display: none;
}
body[data-lang="en"] [data-en] { display: block; }
body[data-lang="he"] [data-he] { display: block; }
body[data-lang="th"] [data-th] { display: block; }

/* Inline lang spans */
body[data-lang="en"] span[data-en],
body[data-lang="he"] span[data-he],
body[data-lang="th"] span[data-th] { display: inline; }

/* Flex items */
body[data-lang="en"] a[data-en],
body[data-lang="he"] a[data-he],
body[data-lang="th"] a[data-th] { display: flex; }

/* Table rows */
body[data-lang="en"] tr[data-en],
body[data-lang="he"] tr[data-he],
body[data-lang="th"] tr[data-th] { display: table-row; }