/* ============================================
   LED Learning Platform – Main CSS
   ============================================ */

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

/* ---- CSS Variables ---- */
:root {
  --primary: #6c63ff;
  --primary-dark: #5a53d4;
  --primary-light: #ede9fe;
  --accent: #ff6584;
  --success: #22c55e;
  --warning: #f59e0b;
  --danger: #ef4444;
  --info: #3b82f6;

  --bg: #0f0f1a;
  --bg-card: #1a1a2e;
  --bg-sidebar: #13132a;
  --bg-code: #0d0d1a;
  --border: rgba(255,255,255,0.08);

  --text: #e2e8f0;
  --text-muted: #94a3b8;
  --text-heading: #f1f5f9;

  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 4px 24px rgba(0,0,0,0.4);
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.2);

  --sidebar-w: 280px;
  --header-h: 64px;

  --transition: 0.2s ease;
}

/* Light mode overrides */
[data-theme="light"] {
  --bg: #f8fafc;
  --bg-card: #ffffff;
  --bg-sidebar: #f1f5f9;
  --bg-code: #1e293b;
  --border: rgba(0,0,0,0.08);
  --text: #334155;
  --text-muted: #64748b;
  --text-heading: #0f172a;
  --shadow: 0 4px 24px rgba(0,0,0,0.08);
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.06);
}

/* ---- Reset ---- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; overflow-x: hidden; }
body {
  font-family: 'Inter', sans-serif;
  overflow-x: hidden;
  position: relative;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  min-height: 100vh;
  transition: background var(--transition), color var(--transition);
  overflow-wrap: break-word;
}

img { max-width: 100%; }
a { color: var(--primary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--primary-dark); }

/* ---- Typography ---- */
h1,h2,h3,h4,h5,h6 { color: var(--text-heading); font-weight: 700; line-height: 1.3; }
h1 { font-size: clamp(2rem, 5vw, 3.5rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2.25rem); }
h3 { font-size: 1.35rem; }
h4 { font-size: 1.1rem; }
p { color: var(--text); }

/* ---- Navbar ---- */
.navbar {
  position: sticky; top: 0; z-index: 1000;
  height: var(--header-h);
  background: rgba(15,15,26,0.85);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  display: flex; align-items: center;
}
[data-theme="light"] .navbar {
  background: rgba(248,250,252,0.85);
}
.navbar-inner {
  max-width: 1280px; margin: 0 auto;
  padding: 0 1.5rem;
  display: flex; align-items: center; justify-content: space-between;
  width: 100%;
}
.navbar-brand {
  font-size: 1.4rem; font-weight: 800;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.navbar-nav { display: flex; align-items: center; gap: 0.25rem; }
.navbar-nav a {
  padding: 0.4rem 0.85rem; border-radius: var(--radius-sm);
  font-size: 0.9rem; font-weight: 500; color: var(--text-muted);
  transition: all var(--transition);
}
.navbar-nav a:hover, .navbar-nav a.active {
  color: var(--text); background: var(--border);
}
.navbar-actions { display: flex; align-items: center; gap: 0.75rem; }

/* Search form in navbar */
.navbar-search { position: relative; }
.navbar-search input {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: 99px; padding: 0.4rem 1rem 0.4rem 2.5rem;
  color: var(--text); font-size: 0.875rem; width: 200px;
  transition: all var(--transition);
}
.navbar-search input:focus {
  outline: none; border-color: var(--primary); width: 260px;
}
.navbar-search .search-icon {
  position: absolute; left: 0.75rem; top: 50%; transform: translateY(-50%);
  color: var(--text-muted); font-size: 0.85rem;
}

/* ---- Buttons ---- */
.btn {
  display: inline-flex; align-items: center; gap: 0.4rem;
  padding: 0.55rem 1.25rem; border-radius: var(--radius-sm);
  font-size: 0.9rem; font-weight: 600; cursor: pointer;
  border: none; transition: all var(--transition); text-decoration: none;
  line-height: 1;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); color: #fff; transform: translateY(-1px); box-shadow: 0 6px 20px rgba(108,99,255,0.35); }
.btn-outline { background: transparent; border: 1.5px solid var(--primary); color: var(--primary); }
.btn-outline:hover { background: var(--primary); color: #fff; }
.btn-success { background: var(--success); color: #fff; }
.btn-success:hover { background: #16a34a; color: #fff; }
.btn-danger { background: var(--danger); color: #fff; }
.btn-danger:hover { background: #dc2626; color: #fff; }
.btn-ghost { background: transparent; border: 1px solid var(--border); color: var(--text-muted); }
.btn-ghost:hover { background: var(--border); color: var(--text); }
.btn-sm { padding: 0.35rem 0.85rem; font-size: 0.8rem; }
.btn-lg { padding: 0.75rem 1.75rem; font-size: 1rem; }
.btn-icon { padding: 0.5rem; border-radius: var(--radius-sm); }

/* ---- Cards ---- */
.card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); overflow: hidden;
  transition: all var(--transition);
  box-shadow: var(--shadow-sm);
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow); border-color: rgba(108,99,255,0.25); }
.card-body { padding: 1.5rem; }
.card-header { padding: 1rem 1.5rem; border-bottom: 1px solid var(--border); }
.card-footer { padding: 1rem 1.5rem; border-top: 1px solid var(--border); }

/* Course card */
.course-card { display: flex; flex-direction: column; }
.course-card .thumbnail {
  position: relative; height: 180px; overflow: hidden;
  background: linear-gradient(135deg, #1a1a4e, #2d2055);
}
.course-card .thumbnail img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.5s ease; }
.course-card:hover .thumbnail img { transform: scale(1.06); }
.course-card .badge { position: absolute; top: 0.75rem; right: 0.75rem; }
.course-card .card-body { flex: 1; display: flex; flex-direction: column; gap: 0.5rem; }
.course-card h3 { font-size: 1.1rem; }
.course-card p { font-size: 0.875rem; color: var(--text-muted); flex: 1; }
.course-card .meta { display: flex; align-items: center; gap: 1rem; font-size: 0.8rem; color: var(--text-muted); margin-top: 0.5rem; }

/* ---- Badge ---- */
.badge {
  display: inline-flex; align-items: center; gap: 0.25rem;
  padding: 0.25rem 0.7rem; border-radius: 99px;
  font-size: 0.75rem; font-weight: 600;
}
.badge-primary { background: var(--primary-light); color: var(--primary); }
.badge-success { background: rgba(34,197,94,0.15); color: var(--success); }
.badge-warning { background: rgba(245,158,11,0.15); color: var(--warning); }
.badge-danger  { background: rgba(239,68,68,0.15); color: var(--danger); }
.badge-muted   { background: var(--border); color: var(--text-muted); }

/* ---- Hero Section ---- */
.hero {
  min-height: 90vh; display: flex; align-items: center;
  position: relative; overflow: hidden;
  background: radial-gradient(ellipse at 20% 50%, rgba(108,99,255,0.15) 0%, transparent 60%),
              radial-gradient(ellipse at 80% 20%, rgba(255,101,132,0.12) 0%, transparent 50%);
}
.hero-content { position: relative; z-index: 1; }
.hero-eyebrow {
  display: inline-flex; align-items: center; gap: 0.5rem;
  background: var(--primary-light); color: var(--primary);
  padding: 0.4rem 1rem; border-radius: 99px; font-size: 0.875rem; font-weight: 600;
  margin-bottom: 1.5rem;
}
.hero h1 span { background: linear-gradient(135deg, var(--primary), var(--accent)); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.hero p { font-size: 1.15rem; color: var(--text-muted); max-width: 560px; margin: 1.25rem 0 2rem; }
.hero-btns { display: flex; gap: 1rem; flex-wrap: wrap; }

/* floating glow blobs */
.blob {
  position: absolute; border-radius: 50%; filter: blur(80px); opacity: 0.35; pointer-events: none;
  animation: blobFloat 8s ease-in-out infinite alternate;
}
.blob-1 { width: 400px; height: 400px; background: var(--primary); top: -100px; right: 5%; }
.blob-2 { width: 300px; height: 300px; background: var(--accent); bottom: 0; right: 30%; animation-delay: -4s; }
@keyframes blobFloat { from { transform: translateY(0) scale(1); } to { transform: translateY(-30px) scale(1.05); } }

/* ---- Container ---- */
.container { max-width: 1280px; margin: 0 auto; padding: 0 1.5rem; }
.section { padding: 5rem 0; }
.section-sm { padding: 3rem 0; }

/* ---- Grid ---- */
.grid-courses { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 300px), 1fr)); gap: 1.5rem; }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 250px), 1fr)); gap: 1.5rem; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; }

/* ---- Progress bar ---- */
.progress-bar {
  height: 6px; background: var(--border); border-radius: 99px; overflow: hidden;
}
.progress-fill {
  height: 100%; background: linear-gradient(90deg, var(--primary), var(--accent));
  border-radius: 99px; transition: width 0.5s ease;
}
.progress-info { display: flex; justify-content: space-between; font-size: 0.8rem; color: var(--text-muted); margin-bottom: 0.35rem; }

/* ---- Lesson Page Layout ---- */
.lesson-layout {
  display: grid;
  grid-template-columns: var(--sidebar-w) minmax(0, 1fr);
  min-height: calc(100vh - var(--header-h));
}

/* Sidebar */
.lesson-sidebar {
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border);
  transition: transform var(--transition);
}
.sidebar-inner {
  position: sticky; top: var(--header-h);
  height: calc(100vh - var(--header-h));
  overflow-y: auto; overflow-x: hidden;
  padding: 1.25rem 0;
}
.sidebar-inner::-webkit-scrollbar { width: 4px; }
.sidebar-inner::-webkit-scrollbar-thumb { background: var(--border); border-radius: 99px; }

.sidebar-course-title {
  padding: 0 1.25rem 1rem; font-size: 0.85rem; font-weight: 700;
  color: var(--primary); text-transform: uppercase; letter-spacing: 0.05em;
  border-bottom: 1px solid var(--border); margin-bottom: 0.75rem;
}
.sidebar-section { margin-bottom: 0.25rem; }
.sidebar-section-title {
  padding: 0.5rem 1.25rem; font-size: 0.8rem; font-weight: 700;
  color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.07em;
}
.sidebar-lesson {
  display: flex; align-items: center; gap: 0.6rem;
  padding: 0.55rem 1.25rem; font-size: 0.875rem; color: var(--text-muted);
  transition: all var(--transition); cursor: pointer; text-decoration: none;
  border-left: 2px solid transparent;
}
.sidebar-lesson:hover { color: var(--text); background: rgba(108,99,255,0.07); border-left-color: var(--primary); }
.sidebar-lesson.active { color: var(--primary); background: rgba(108,99,255,0.12); border-left-color: var(--primary); font-weight: 600; }
.sidebar-lesson.completed .lesson-dot { background: var(--success); }
.lesson-dot {
  width: 8px; height: 8px; border-radius: 50%; flex-shrink: 0;
  background: var(--border); transition: background var(--transition);
}

/* Sidebar toggle button */
.sidebar-toggle {
  display: none; position: fixed; bottom: 2rem; right: 1.5rem;
  z-index: 200; background: var(--primary); color: #fff;
  border: none; border-radius: 50%; width: 48px; height: 48px;
  font-size: 1.2rem; cursor: pointer; box-shadow: 0 4px 16px rgba(108,99,255,0.4);
  align-items: center; justify-content: center;
}

/* Lesson content */
.lesson-content { padding: 2.5rem; max-width: 100%; width: 100%; box-sizing: border-box; }
.lesson-header { margin-bottom: 2rem; padding-bottom: 1.5rem; border-bottom: 1px solid var(--border); overflow-wrap: break-word; word-break: break-word; }
.lesson-breadcrumb { font-size: 0.8rem; color: var(--text-muted); margin-bottom: 0.75rem; }
.lesson-breadcrumb a { color: var(--text-muted); }
.lesson-breadcrumb a:hover { color: var(--primary); }
.lesson-title { font-size: 2rem; font-weight: 800; margin-bottom: 0.5rem; }
.lesson-meta { display: flex; align-items: center; gap: 1rem; flex-wrap: wrap; }

/* Code block */
.code-block {
  background: var(--bg-code); border: 1px solid var(--border);
  border-radius: var(--radius); overflow: hidden; margin: 1.5rem 0;
  max-width: 100%; box-sizing: border-box;
}
.code-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 0.75rem 1.25rem; border-bottom: 1px solid var(--border);
  background: rgba(255,255,255,0.03);
}
.code-dots { display: flex; gap: 6px; }
.code-dots span { width: 12px; height: 12px; border-radius: 50%; }
.code-dots .dot-red { background: #ff5f57; }
.code-dots .dot-yellow { background: #febc2e; }
.code-dots .dot-green { background: #28c840; }
.code-lang { font-size: 0.75rem; color: var(--text-muted); font-family: 'JetBrains Mono', monospace; }
.code-copy { background: none; border: 1px solid var(--border); color: var(--text-muted); padding: 0.2rem 0.6rem; border-radius: 4px; font-size: 0.75rem; cursor: pointer; transition: all var(--transition); }
.code-copy:hover { border-color: var(--primary); color: var(--primary); }
.code-block pre {
  padding: 1.5rem; margin: 0; overflow-x: auto; box-sizing: border-box; max-width: 100%;
  font-family: 'JetBrains Mono', monospace; font-size: 0.875rem;
  line-height: 1.8; color: #a9b7c6;
}
.code-block code { font-family: inherit; white-space: pre; }

/* Output preview */
.output-preview {
  background: #fff; border: 1px solid var(--border);
  border-radius: var(--radius); overflow: hidden; margin: 1.5rem 0;
  max-width: 100%; box-sizing: border-box;
}
.output-header { padding: 0.6rem 1rem; background: #f1f3f5; border-bottom: 1px solid #ddd; font-size: 0.8rem; font-weight: 600; color: #555; }
.output-body { padding: 1.5rem; min-height: 100px; }
.output-iframe { width: 100%; min-height: 200px; border: none; }

/* Lesson prose – rich content */
.lesson-prose {
  font-size: 1.05rem; line-height: 1.85; width: 100%; max-width: 100%;
  overflow-wrap: anywhere; word-break: break-word; box-sizing: border-box;
}
.lesson-prose h2, .lesson-prose h3 { margin: 2rem 0 1rem; }
.lesson-prose p { margin-bottom: 1rem; }
.lesson-prose ul, .lesson-prose ol { padding-left: 1.5rem; margin-bottom: 1rem; }
.lesson-prose li { margin-bottom: 0.4rem; }
.lesson-prose img, .lesson-prose iframe { max-width: 100%; height: auto; }
.lesson-prose table { width: 100%; display: block; overflow-x: auto; border-collapse: collapse; margin-bottom: 1.5rem; }
.lesson-prose th, .lesson-prose td { border: 1px solid var(--border); padding: 0.5rem 0.75rem; }
.lesson-prose pre { padding: 1.25rem; margin: 1.5rem 0; overflow-x: auto; background: var(--bg-code); border-radius: var(--radius-sm); max-width: 100%; }
.lesson-prose code {
  font-family: 'JetBrains Mono', monospace; font-size: 0.87em;
  background: rgba(108,99,255,0.12); color: var(--primary);
  padding: 0.15em 0.45em; border-radius: 4px;
  word-break: break-all; overflow-wrap: break-word; white-space: pre-wrap;
}
.lesson-prose pre code { background: none; color: inherit; padding: 0; word-break: normal; white-space: pre; }
.lesson-prose blockquote {
  border-left: 3px solid var(--primary); padding: 0.75rem 1.25rem;
  background: rgba(108,99,255,0.07); border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 1.5rem 0;
}

/* Practice steps */
.practice-steps { margin: 2.5rem 0; }
.practice-steps h3 { display: flex; align-items: center; gap: 0.5rem; margin-bottom: 1.25rem; }
.step-item {
  display: flex; gap: 1rem; align-items: flex-start;
  padding: 1rem 1.25rem; background: var(--bg-card);
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  margin-bottom: 0.75rem; transition: border-color var(--transition);
  max-width: 100%; box-sizing: border-box;
}
.step-item:hover { border-color: var(--primary); }
.step-number {
  width: 30px; height: 30px; border-radius: 50%;
  background: var(--primary-light); color: var(--primary);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.8rem; font-weight: 700; flex-shrink: 0;
}
.step-body { flex: 1; }
.step-instruction { font-weight: 500; margin-bottom: 0.35rem; }
.step-output { font-family: 'JetBrains Mono', monospace; font-size: 0.8rem; color: var(--text-muted); background: var(--bg-code); padding: 0.4rem 0.75rem; border-radius: 4px; margin-top: 0.4rem; overflow-x: auto; word-break: break-word; white-space: pre-wrap; }

/* Lesson navigation */
.lesson-nav {
  display: flex; justify-content: space-between; align-items: center;
  padding: 2rem 0; border-top: 1px solid var(--border); margin-top: 3rem;
  gap: 1rem;
}
.lesson-nav a { max-width: 45%; }
.lesson-nav .nav-prev { text-align: left; }
.lesson-nav .nav-next { text-align: right; margin-left: auto; }
.nav-label { font-size: 0.75rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.07em; margin-bottom: 0.25rem; }
.nav-title { font-weight: 600; color: var(--text); font-size: 0.9rem; }

/* Complete button */
.completion-box {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.5rem; text-align: center;
  margin: 2rem 0;
}
.completion-box.done { border-color: var(--success); background: rgba(34,197,94,0.06); }

/* ---- Alert / Flash ---- */
.alert {
  display: flex; align-items: center; gap: 0.75rem;
  padding: 0.85rem 1.25rem; border-radius: var(--radius-sm);
  font-size: 0.9rem; border: 1px solid transparent; margin-bottom: 1rem;
}
.alert-success { background: rgba(34,197,94,0.1); border-color: rgba(34,197,94,0.3); color: #22c55e; }
.alert-error   { background: rgba(239,68,68,0.1); border-color: rgba(239,68,68,0.3); color: #ef4444; }
.alert-info    { background: rgba(59,130,246,0.1); border-color: rgba(59,130,246,0.3); color: #3b82f6; }

/* ---- Forms ---- */
.auth-wrapper {
  min-height: 100vh; display: flex; align-items: center; justify-content: center;
  padding: 2rem 1.5rem; position: relative; overflow: hidden;
  background: radial-gradient(ellipse at top left, rgba(108,99,255,0.15), transparent 40%),
              radial-gradient(ellipse at bottom right, rgba(255,101,132,0.12), transparent 40%);
}
.auth-card {
  width: 100%; max-width: 420px;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 2.5rem;
  box-shadow: 0 12px 40px rgba(0,0,0,0.4);
  position: relative; z-index: 10;
}
.auth-brand { text-align: center; margin-bottom: 2rem; }
.auth-brand .logo {
  font-size: 1.8rem; font-weight: 800;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text; color: transparent;
}
.form-group { margin-bottom: 1.25rem; }
.form-label { display: block; font-size: 0.875rem; font-weight: 600; color: var(--text); margin-bottom: 0.4rem; }
.form-control {
  width: 100%; padding: 0.65rem 1rem;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius-sm); color: var(--text); font-size: 0.9rem;
  transition: all var(--transition); font-family: inherit;
}
.form-control:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px rgba(108,99,255,0.15); }
.form-control::placeholder { color: var(--text-muted); }
textarea.form-control { resize: vertical; min-height: 140px; }
.form-error { display:flex; align-items:center; gap:.35rem; font-size: 0.8rem; color: var(--danger); margin-top: 0.3rem; }
.form-control.input-error {
  border-color: var(--danger);
  box-shadow: 0 0 0 3px rgba(239,68,68,0.15);
}

/* Dark-mode toggle */
.theme-toggle {
  background: none; border: 1px solid var(--border); border-radius: 99px;
  cursor: pointer; width: 40px; height: 40px;
  display: flex; align-items: center; justify-content: center;
  color: var(--text-muted); font-size: 1rem; transition: all var(--transition);
}
.theme-toggle:hover { border-color: var(--primary); color: var(--primary); }

/* ---- Features section (homepage) ---- */
.feature-card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 2rem 1.75rem;
  text-align: center; transition: all var(--transition);
}
.feature-card:hover { transform: translateY(-4px); border-color: rgba(108,99,255,0.4); }
.feature-icon {
  width: 60px; height: 60px; border-radius: var(--radius);
  background: var(--primary-light); color: var(--primary);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.5rem; margin: 0 auto 1.25rem;
}
.feature-card h3 { margin-bottom: 0.5rem; }
.feature-card p { font-size: 0.9rem; color: var(--text-muted); }

/* Stats stripe */
.stats-stripe {
  background: var(--bg-card); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border);
  padding: 2.5rem 0;
}
.stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 2rem; text-align: center; }
.stat-value { font-size: 2.5rem; font-weight: 800; background: linear-gradient(135deg, var(--primary), var(--accent)); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.stat-label { font-size: 0.875rem; color: var(--text-muted); margin-top: 0.25rem; }

/* ---- Footer ---- */
.footer {
  background: var(--bg-card); border-top: 1px solid var(--border);
  padding: 3rem 0 1.5rem; margin-top: auto;
}
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 3rem; margin-bottom: 2rem; }
.footer-brand .logo { font-size: 1.4rem; font-weight: 800; background: linear-gradient(135deg, var(--primary), var(--accent)); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.footer p { font-size: 0.875rem; color: var(--text-muted); margin-top: 0.5rem; }
.footer-col h4 { font-size: 0.9rem; font-weight: 700; margin-bottom: 1rem; color: var(--text); }
.footer-col ul { list-style: none; display: flex; flex-direction: column; gap: 0.5rem; }
.footer-col ul a { font-size: 0.875rem; color: var(--text-muted); }
.footer-col ul a:hover { color: var(--primary); }
.footer-bottom { border-top: 1px solid var(--border); padding-top: 1.25rem; display: flex; justify-content: space-between; font-size: 0.8rem; color: var(--text-muted); }

/* ---- Empty state ---- */
.empty-state { text-align: center; padding: 5rem 2rem; }
.empty-icon { font-size: 4rem; margin-bottom: 1.25rem; opacity: 0.4; }
.empty-state h3 { margin-bottom: 0.5rem; }
.empty-state p { color: var(--text-muted); font-size: 0.9rem; }

/* ---- Loading spinner ---- */
.spinner {
  width: 36px; height: 36px; border: 3px solid var(--border);
  border-top-color: var(--primary); border-radius: 50%;
  animation: spin 0.7s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ---- Pagination ---- */
.pagination { display: flex; justify-content: center; gap: 0.5rem; margin-top: 2.5rem; flex-wrap: wrap; }
.pagination a, .pagination span {
  padding: 0.45rem 0.85rem; border-radius: var(--radius-sm);
  font-size: 0.875rem; border: 1px solid var(--border); color: var(--text-muted); min-width: 38px; text-align: center;
}
.pagination a:hover { border-color: var(--primary); color: var(--primary); }
.pagination .active { background: var(--primary); border-color: var(--primary); color: #fff; }

/* ---- Section heading ---- */
.section-heading { text-align: center; margin-bottom: 3rem; }
.section-heading .eyebrow { color: var(--primary); font-size: 0.875rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; margin-bottom: 0.5rem; }
.section-heading h2 { margin-bottom: 0.75rem; }
.section-heading p { color: var(--text-muted); max-width: 540px; margin: 0 auto; }

/* ---- Course detail ---- */
.course-hero {
  background: linear-gradient(135deg, rgba(108,99,255,0.15), rgba(255,101,132,0.1));
  border-bottom: 1px solid var(--border); padding: 4rem 0;
}
.course-hero-inner { display: grid; grid-template-columns: 1fr auto; gap: 3rem; align-items: center; }
.course-meta-list { display: flex; gap: 1.5rem; flex-wrap: wrap; margin-top: 1rem; }
.course-meta-list span { display: flex; align-items: center; gap: 0.4rem; font-size: 0.875rem; color: var(--text-muted); }
.course-thumbnail-preview { width: 300px; height: 200px; object-fit: cover; border-radius: var(--radius); box-shadow: 0 12px 40px rgba(0,0,0,0.4); }

.section-accordion { margin-bottom: 1rem; border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.section-accordion-header {
  padding: 1rem 1.5rem; display: flex; justify-content: space-between; align-items: center;
  cursor: pointer; background: var(--bg-card); font-weight: 600;
  transition: background var(--transition);
}
.section-accordion-header:hover { background: rgba(108,99,255,0.05); }
.section-accordion-body { border-top: 1px solid var(--border); }
.lesson-list-item {
  display: flex; align-items: center; justify-content: space-between;
  padding: 0.85rem 1.5rem; border-bottom: 1px solid var(--border);
  transition: background var(--transition);
}
.lesson-list-item:last-child { border-bottom: none; }
.lesson-list-item:hover { background: rgba(108,99,255,0.05); }
.lesson-list-item .lesson-name { display: flex; align-items: center; gap: 0.6rem; font-size: 0.9rem; color: var(--text); }
.lesson-list-item .lesson-name .icon { color: var(--text-muted); font-size: 0.8rem; }

/* ---- Responsive ---- */
@media (max-width: 1024px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .course-hero-inner { grid-template-columns: 1fr; }
  .course-thumbnail-preview { display: none; }
  .lesson-layout { grid-template-columns: minmax(0, 1fr); }
  .lesson-sidebar {
    display: none; position: fixed; left: 0; top: var(--header-h);
    width: var(--sidebar-w); height: calc(100vh - var(--header-h));
    z-index: 500; transform: translateX(-100%);
  }
  .lesson-sidebar.open { display: block; transform: translateX(0); }
  .sidebar-toggle { display: flex; }
  .navbar-search { display: none; }
  .navbar-nav { display: none; }
  .grid-2 { grid-template-columns: minmax(0, 1fr); }
}

@media (max-width: 768px) {
  .lesson-content { padding: 1.5rem 1rem; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: 2rem; }
  .hero-btns { flex-direction: column; align-items: flex-start; }
  .lesson-nav { flex-direction: column; gap: 1.5rem; }
  .lesson-nav a { max-width: 100%; width: 100%; text-align: center; border: 1px solid var(--border); padding: 1rem; border-radius: var(--radius-sm); }
  .lesson-nav .nav-prev, .lesson-nav .nav-next { text-align: center; margin: 0 auto; }
}

@media (max-width: 480px) {
  .navbar-brand { font-size: 1.1rem; }
  .section { padding: 3rem 0; }
  .hero p { font-size: 0.95rem; margin-bottom: 1.5rem; }
}

/* ---- Site Link Buttons (homepage pintasan) ---- */
.site-link-btn {
  display: inline-flex; align-items: center; gap: 0.6rem;
  padding: 0.7rem 1.5rem; border-radius: 99px;
  border: 2px solid color-mix(in srgb, var(--link-color) 40%, transparent);
  background: color-mix(in srgb, var(--link-color) 8%, transparent);
  color: var(--link-color);
  font-size: 0.9rem; font-weight: 600; text-decoration: none;
  transition: all 0.25s; white-space: nowrap;
}
.site-link-btn:hover {
  background: color-mix(in srgb, var(--link-color) 18%, transparent);
  border-color: var(--link-color);
  transform: translateY(-2px);
  box-shadow: 0 6px 24px color-mix(in srgb, var(--link-color) 25%, transparent);
}
.site-link-icon { font-size: 1.1rem; }

/* ---- Referensi Tutorial (lesson page) ---- */
.ref-tutorial-box {
  margin: 2rem 0;
  border: 1px solid rgba(108,99,255,0.2);
  border-radius: var(--radius);
  overflow: hidden;
  background: rgba(108,99,255,0.04);
}
.ref-tutorial-header {
  padding: .75rem 1.25rem;
  font-size: .82rem; font-weight: 700; letter-spacing:.04em;
  text-transform: uppercase; color: var(--primary);
  border-bottom: 1px solid rgba(108,99,255,0.15);
  display: flex; align-items: center; gap: .5rem;
}
.ref-tutorial-links {
  display: flex; flex-direction: column; gap: .5rem;
  padding: .875rem 1.25rem;
}
.ref-tutorial-btn {
  display: flex; align-items: center; gap: .75rem;
  padding: .65rem 1rem; border-radius: 8px;
  border: 1.5px solid color-mix(in srgb, var(--ref-color) 35%, transparent);
  background: color-mix(in srgb, var(--ref-color) 6%, transparent);
  color: var(--ref-color);
  font-size: .875rem; font-weight: 600; text-decoration: none;
  transition: all .22s;
}
.ref-tutorial-btn:hover {
  background: color-mix(in srgb, var(--ref-color) 14%, transparent);
  border-color: var(--ref-color);
  transform: translateX(3px);
  box-shadow: 0 4px 16px color-mix(in srgb, var(--ref-color) 20%, transparent);
}