@import url('https://fonts.googleapis.com/css2?family=Syne:wght@400;600;700;800&family=DM+Sans:ital,wght@0,300;0,400;0,500;1,300&family=JetBrains+Mono:wght@400;500&display=swap');

:root {
  --bg-dark: #0a0b0f;
  --bg-card: #111318;
  --bg-card2: #161820;
  --border: rgba(255,255,255,0.07);
  --accent1: #6c63ff;
  --accent2: #00d4aa;
  --accent3: #ff6b6b;
  --accent4: #ffd166;
  --text-primary: #e8eaf0;
  --text-secondary: #8b90a7;
  --text-muted: #555a72;
  --glow1: rgba(108,99,255,0.15);
  --glow2: rgba(0,212,170,0.1);
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg-dark);
  color: var(--text-primary);
  font-family: 'DM Sans', sans-serif;
  font-size: 16px;
  line-height: 1.75;
  min-height: 100vh;
  overflow-x: hidden;
}

body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 50% at 20% 10%, rgba(108,99,255,0.12) 0%, transparent 60%),
    radial-gradient(ellipse 60% 40% at 80% 80%, rgba(0,212,170,0.08) 0%, transparent 60%),
    radial-gradient(ellipse 40% 60% at 50% 50%, rgba(22,24,32,0.4) 0%, transparent 80%);
  pointer-events: none;
  z-index: 0;
}

/* NAV */
nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(10,11,15,0.85);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: 0 2rem;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  font-family: 'Syne', sans-serif;
  font-weight: 800;
  font-size: 1rem;
  color: var(--accent1);
  text-decoration: none;
  letter-spacing: 0.02em;
}

.nav-links {
  display: flex;
  gap: 0.3rem;
  list-style: none;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.72rem;
  font-weight: 500;
  padding: 4px 10px;
  border-radius: 20px;
  transition: all 0.2s;
  font-family: 'JetBrains Mono', monospace;
}

.nav-links a:hover, .nav-links a.active {
  background: var(--glow1);
  color: var(--accent1);
}

/* LAYOUT */
.page-wrapper {
  position: relative;
  z-index: 1;
  max-width: 960px;
  margin: 0 auto;
  padding: 100px 2rem 4rem;
}

/* HERO */
.chapter-hero {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border);
}

.chapter-tag {
  display: inline-block;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--accent2);
  background: rgba(0,212,170,0.1);
  border: 1px solid rgba(0,212,170,0.2);
  padding: 4px 12px;
  border-radius: 20px;
  margin-bottom: 1rem;
  letter-spacing: 0.08em;
}

.chapter-hero h1 {
  font-family: 'Syne', sans-serif;
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 800;
  line-height: 1.15;
  background: linear-gradient(135deg, #fff 30%, var(--accent1) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 1rem;
}

.chapter-hero p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 680px;
  line-height: 1.7;
}

/* CONTENT CARDS */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 2rem;
  margin-bottom: 1.5rem;
  transition: border-color 0.3s;
}

.card:hover { border-color: rgba(108,99,255,0.3); }

.card h2 {
  font-family: 'Syne', sans-serif;
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--accent1);
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.card h2 .icon {
  width: 28px; height: 28px;
  background: var(--glow1);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
}

.card h3 {
  font-family: 'Syne', sans-serif;
  font-size: 1rem;
  font-weight: 600;
  color: var(--accent2);
  margin: 1.2rem 0 0.5rem;
}

.card p { color: var(--text-secondary); margin-bottom: 0.8rem; }

/* HIGHLIGHT BOX */
.highlight {
  background: linear-gradient(135deg, rgba(108,99,255,0.1), rgba(0,212,170,0.05));
  border-left: 3px solid var(--accent1);
  border-radius: 0 12px 12px 0;
  padding: 1rem 1.2rem;
  margin: 1rem 0;
  color: var(--text-primary);
  font-size: 0.95rem;
}

.highlight.green { border-color: var(--accent2); background: linear-gradient(135deg, rgba(0,212,170,0.1), rgba(0,212,170,0.03)); }
.highlight.red { border-color: var(--accent3); background: linear-gradient(135deg, rgba(255,107,107,0.1), rgba(255,107,107,0.03)); }
.highlight.yellow { border-color: var(--accent4); background: linear-gradient(135deg, rgba(255,209,102,0.1), rgba(255,209,102,0.03)); }

/* LISTS */
ul.styled, ol.styled {
  padding-left: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

ul.styled li, ol.styled li {
  padding-left: 1.5rem;
  position: relative;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

ul.styled li::before {
  content: '▸';
  position: absolute;
  left: 0;
  color: var(--accent1);
  font-size: 0.8rem;
  top: 0.15em;
}

ol.styled { counter-reset: item; }
ol.styled li { counter-increment: item; }
ol.styled li::before {
  content: counter(item);
  position: absolute;
  left: 0;
  color: var(--accent2);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
  font-weight: 600;
  top: 0.1em;
}

/* DIAGRAM */
.diagram-box {
  background: var(--bg-card2);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  margin: 1.5rem 0;
  overflow-x: auto;
}

.diagram-box .diagram-title {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--accent4);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 1.2rem;
}

/* GRID */
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; }

@media (max-width: 640px) {
  .grid-2, .grid-3 { grid-template-columns: 1fr; }
  nav { padding: 0 1rem; }
  .page-wrapper { padding: 80px 1rem 3rem; }
}

/* MINI CARD */
.mini-card {
  background: var(--bg-card2);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.2rem;
  text-align: center;
  transition: all 0.3s;
}

.mini-card:hover { border-color: var(--accent1); transform: translateY(-2px); }

.mini-card .label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 0.4rem;
}

.mini-card .value {
  font-family: 'Syne', sans-serif;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
}

/* CODE */
code {
  font-family: 'JetBrains Mono', monospace;
  background: rgba(108,99,255,0.12);
  color: var(--accent2);
  padding: 2px 7px;
  border-radius: 5px;
  font-size: 0.85em;
}

/* TABLE */
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

th {
  background: rgba(108,99,255,0.15);
  color: var(--accent1);
  font-family: 'Syne', sans-serif;
  font-weight: 600;
  padding: 0.7rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

td {
  padding: 0.6rem 1rem;
  color: var(--text-secondary);
  border-bottom: 1px solid rgba(255,255,255,0.04);
}

tr:hover td { background: rgba(255,255,255,0.02); }

/* NAV FOOTER */
.page-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
  gap: 1rem;
}

.page-nav a {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.8rem 1.4rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.88rem;
  transition: all 0.2s;
  flex: 1;
}

.page-nav a:first-child { justify-content: flex-start; }
.page-nav a:last-child { justify-content: flex-end; }

.page-nav a:hover {
  border-color: var(--accent1);
  color: var(--accent1);
}

/* SVG DIAGRAM */
svg text { font-family: 'DM Sans', sans-serif; }

/* BADGE */
.badge {
  display: inline-block;
  font-size: 0.72rem;
  font-family: 'JetBrains Mono', monospace;
  padding: 2px 10px;
  border-radius: 20px;
  font-weight: 500;
}

.badge-purple { background: rgba(108,99,255,0.2); color: var(--accent1); border: 1px solid rgba(108,99,255,0.3); }
.badge-green { background: rgba(0,212,170,0.15); color: var(--accent2); border: 1px solid rgba(0,212,170,0.25); }
.badge-red { background: rgba(255,107,107,0.15); color: var(--accent3); border: 1px solid rgba(255,107,107,0.25); }
.badge-yellow { background: rgba(255,209,102,0.15); color: var(--accent4); border: 1px solid rgba(255,209,102,0.25); }