/* ═══════════════════════════════════════════════════════
   OrbLayout Learning Center — Master Stylesheet
   ═══════════════════════════════════════════════════════ */

/* ── Reset & Base ──────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0a0a1a;
  --bg-card: #12122a;
  --bg-code: #0d0d20;
  --bg-surface: #16163a;
  --bg-hover: #1c1c4a;
  --text: #e0e0ff;
  --text-dim: #8888bb;
  --text-muted: #5555aa;
  --accent: #6c5ce7;
  --accent-light: #a29bfe;
  --accent-glow: rgba(108, 92, 231, 0.3);
  --green: #00e676;
  --green-dim: #00c853;
  --orange: #ff9100;
  --pink: #ff6b9d;
  --cyan: #00e5ff;
  --red: #ff5252;
  --yellow: #ffd740;
  --radius: 12px;
  --radius-sm: 8px;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'SF Mono', 'Consolas', monospace;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --shadow: 0 4px 32px rgba(0,0,0,0.4);
  --shadow-glow: 0 0 40px rgba(108, 92, 231, 0.15);
  --max-width: 880px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent-light); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--accent); }

img { max-width: 100%; display: block; }

::selection { background: var(--accent); color: #fff; }

/* ── Scrollbar ─────────────────────────────────────── */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--bg-surface); border-radius: 99px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent); }

/* ── Top Navigation Bar ────────────────────────────── */
.top-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  background: rgba(10, 10, 26, 0.85);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(108, 92, 231, 0.15);
  padding: 0 2rem;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.top-nav .logo {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.top-nav .logo .orb {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px; height: 32px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), #a29bfe);
  font-size: 0.85rem;
  color: #fff;
}
.top-nav .nav-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  list-style: none;
}
.top-nav .nav-links a {
  color: var(--text-dim);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  transition: color var(--transition);
}
.top-nav .nav-links a:hover,
.top-nav .nav-links a.active { color: var(--accent-light); }

/* ── Page Container ────────────────────────────────── */
.page { padding-top: 80px; min-height: 100vh; }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem 4rem;
}

/* ── Hero (Index Page) ─────────────────────────────── */
.hero {
  text-align: center;
  padding: 4rem 0 3rem;
}
.hero .badge {
  display: inline-block;
  background: var(--accent-glow);
  border: 1px solid rgba(108, 92, 231, 0.4);
  color: var(--accent-light);
  padding: 0.35rem 1rem;
  border-radius: 99px;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 1.5rem;
}
.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, #fff 0%, var(--accent-light) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero .subtitle {
  font-size: 1.15rem;
  color: var(--text-dim);
  max-width: 560px;
  margin: 0 auto 2rem;
  line-height: 1.7;
}

/* ── Lesson Cards Grid ─────────────────────────────── */
.lessons-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-top: 2rem;
}
.lesson-card {
  background: var(--bg-card);
  border: 1px solid rgba(108, 92, 231, 0.1);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.lesson-card:hover {
  border-color: rgba(108, 92, 231, 0.4);
  transform: translateY(-3px);
  box-shadow: var(--shadow-glow);
}
.lesson-card .lesson-num {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
}
.lesson-card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: #fff;
}
.lesson-card p {
  font-size: 0.85rem;
  color: var(--text-dim);
  line-height: 1.6;
}
.lesson-card .tag {
  display: inline-block;
  font-size: 0.65rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: 99px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}
.tag.beginner { background: rgba(0, 230, 118, 0.15); color: var(--green); }
.tag.intermediate { background: rgba(255, 145, 0, 0.15); color: var(--orange); }
.tag.advanced { background: rgba(255, 82, 82, 0.15); color: var(--red); }

/* ── Lesson Page Layout ────────────────────────────── */
.lesson-header {
  padding: 3rem 0 2rem;
  border-bottom: 1px solid rgba(108, 92, 231, 0.1);
  margin-bottom: 2.5rem;
}
.lesson-header .lesson-num {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.5rem;
}
.lesson-header h1 {
  font-size: 2.2rem;
  font-weight: 800;
  line-height: 1.2;
  color: #fff;
  margin-bottom: 0.75rem;
}
.lesson-header .lesson-desc {
  font-size: 1.05rem;
  color: var(--text-dim);
  line-height: 1.7;
}

/* ── Table of Contents ─────────────────────────────── */
.toc {
  background: var(--bg-card);
  border: 1px solid rgba(108, 92, 231, 0.12);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin-bottom: 2.5rem;
}
.toc h4 {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}
.toc ol {
  list-style: none;
  counter-reset: toc;
  padding: 0;
}
.toc ol li {
  counter-increment: toc;
  margin-bottom: 0.35rem;
}
.toc ol li a {
  color: var(--text-dim);
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: color var(--transition);
}
.toc ol li a::before {
  content: counter(toc) ".";
  font-weight: 700;
  color: var(--accent);
  font-size: 0.8rem;
  min-width: 1.5rem;
}
.toc ol li a:hover { color: var(--accent-light); }

/* ── Sections ──────────────────────────────────────── */
.section {
  margin-bottom: 3rem;
}
.section h2 {
  font-size: 1.5rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid rgba(108, 92, 231, 0.2);
}
.section h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: #fff;
  margin: 1.5rem 0 0.75rem;
}
.section p {
  color: var(--text-dim);
  margin-bottom: 1rem;
  line-height: 1.8;
}
.section ul, .section ol {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}
.section li {
  color: var(--text-dim);
  margin-bottom: 0.4rem;
  line-height: 1.7;
}
.section li strong {
  color: var(--text);
}

/* ── Code Blocks ───────────────────────────────────── */
.code-block {
  position: relative;
  background: var(--bg-code);
  border: 1px solid rgba(108, 92, 231, 0.12);
  border-radius: var(--radius);
  margin: 1.25rem 0;
  overflow: hidden;
}
.code-block .code-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.6rem 1rem;
  background: rgba(108, 92, 231, 0.06);
  border-bottom: 1px solid rgba(108, 92, 231, 0.08);
}
.code-block .code-label {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
}
.code-block .code-lang {
  font-size: 0.65rem;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.05em;
  text-transform: uppercase;
}
.code-block pre {
  padding: 1.25rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.7;
  color: var(--text);
  tab-size: 2;
}
.code-block code {
  font-family: var(--font-mono);
}

/* Inline code */
.section code, p code, li code, td code {
  background: rgba(108, 92, 231, 0.12);
  color: var(--accent-light);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.85em;
}

/* ── Info / Tip / Warning Boxes ────────────────────── */
.info-box {
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin: 1.5rem 0;
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  line-height: 1.7;
  font-size: 0.9rem;
}
.info-box .icon { font-size: 1.2rem; flex-shrink: 0; margin-top: 2px; }
.info-box p { margin: 0; }

.info-box.tip {
  background: rgba(0, 230, 118, 0.06);
  border: 1px solid rgba(0, 230, 118, 0.2);
  color: var(--green);
}
.info-box.warn {
  background: rgba(255, 145, 0, 0.06);
  border: 1px solid rgba(255, 145, 0, 0.2);
  color: var(--orange);
}
.info-box.note {
  background: rgba(108, 92, 231, 0.06);
  border: 1px solid rgba(108, 92, 231, 0.2);
  color: var(--accent-light);
}
.info-box.danger {
  background: rgba(255, 82, 82, 0.06);
  border: 1px solid rgba(255, 82, 82, 0.2);
  color: var(--red);
}

/* ── Result Preview ────────────────────────────────── */
.result-preview {
  background: #fff;
  color: #333;
  border-radius: var(--radius);
  padding: 1.5rem;
  margin: 1.25rem 0;
  border: 1px solid rgba(108, 92, 231, 0.15);
  position: relative;
}
.result-preview::before {
  content: "OUTPUT";
  position: absolute;
  top: -0.6rem; left: 1rem;
  background: var(--bg);
  padding: 0 0.5rem;
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--green);
}
.result-preview h1 { font-size: 1.5rem; margin-bottom: 0.5rem; }
.result-preview h2 { font-size: 1.25rem; margin-bottom: 0.5rem; }
.result-preview h3 { font-size: 1.1rem; margin-bottom: 0.5rem; }
.result-preview p { margin-bottom: 0.5rem; }
.result-preview .card-demo {
  background: #f5f5f5; padding: 1rem;
  border-radius: 8px; margin: 0.5rem 0;
}

/* ── Side-by-Side Code Comparison ──────────────────── */
.code-compare {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin: 1.5rem 0;
}
.code-compare .code-block { margin: 0; }
@media (max-width: 700px) {
  .code-compare { grid-template-columns: 1fr; }
}

/* ── Tables ────────────────────────────────────────── */
.table-wrap {
  overflow-x: auto;
  margin: 1.25rem 0;
}
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}
th {
  text-align: left;
  padding: 0.75rem 1rem;
  background: rgba(108, 92, 231, 0.08);
  color: var(--accent-light);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  border-bottom: 1px solid rgba(108, 92, 231, 0.15);
}
td {
  padding: 0.65rem 1rem;
  border-bottom: 1px solid rgba(108, 92, 231, 0.06);
  color: var(--text-dim);
}
tr:hover td { background: rgba(108, 92, 231, 0.03); }

/* ── Checkpoint / Exercise Boxes ───────────────────── */
.checkpoint {
  background: linear-gradient(135deg, rgba(108, 92, 231, 0.08), rgba(162, 155, 254, 0.04));
  border: 1px solid rgba(108, 92, 231, 0.2);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin: 2rem 0;
}
.checkpoint h4 {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-light);
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.checkpoint ol, .checkpoint ul {
  padding-left: 1.25rem;
}
.checkpoint li {
  color: var(--text-dim);
  font-size: 0.9rem;
  margin-bottom: 0.35rem;
}

/* ── Lesson Navigation (Bottom) ────────────────────── */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid rgba(108, 92, 231, 0.1);
}
.lesson-nav a {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  padding: 1rem 1.25rem;
  background: var(--bg-card);
  border: 1px solid rgba(108, 92, 231, 0.12);
  border-radius: var(--radius);
  transition: all var(--transition);
  min-width: 200px;
}
.lesson-nav a:hover {
  border-color: rgba(108, 92, 231, 0.4);
  box-shadow: var(--shadow-glow);
}
.lesson-nav a .nav-label {
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.lesson-nav a .nav-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: #fff;
}
.lesson-nav .next { text-align: right; margin-left: auto; }

/* ── Progress Bar ──────────────────────────────────── */
.progress-bar {
  position: fixed;
  top: 60px; left: 0; right: 0;
  height: 3px;
  z-index: 999;
  background: rgba(108, 92, 231, 0.1);
}
.progress-bar .progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent-light));
  border-radius: 0 2px 2px 0;
  transition: width 0.4s ease;
}

/* ── Footer ────────────────────────────────────────── */
.page-footer {
  text-align: center;
  padding: 2rem 0;
  color: var(--text-muted);
  font-size: 0.8rem;
  border-top: 1px solid rgba(108, 92, 231, 0.06);
  margin-top: 2rem;
}
.page-footer a { color: var(--accent); }

/* ── Responsive ────────────────────────────────────── */
@media (max-width: 768px) {
  .hero h1 { font-size: 2rem; }
  .lessons-grid { grid-template-columns: 1fr; }
  .lesson-header h1 { font-size: 1.6rem; }
  .container { padding: 0 1rem 3rem; }
  .top-nav { padding: 0 1rem; }
  .lesson-nav { flex-direction: column; }
  .lesson-nav .next { text-align: left; }
}

/* ── Syntax Highlight Colors (Manual) ──────────────── */
.hl-tag { color: var(--pink); }
.hl-attr { color: var(--orange); }
.hl-string { color: var(--green); }
.hl-bracket { color: var(--yellow); }
.hl-var { color: var(--cyan); }
.hl-comment { color: var(--text-muted); font-style: italic; }
.hl-keyword { color: var(--accent-light); }

/* ── Animations ────────────────────────────────────── */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}
.animate-in { animation: fadeInUp 0.5s ease both; }
.delay-1 { animation-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; }
.delay-3 { animation-delay: 0.3s; }
.delay-4 { animation-delay: 0.4s; }