@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;600;700&family=Noto+Sans+JP:wght@300;400;600;700;900&display=swap');

/* ─── Dark Theme (default) ─── */
:root {
  --font-scale: 1;
  --bg-deep: #0a0e1a;
  --bg-card: #111827;
  --bg-card-hover: #1a2235;
  --bg-surface: #0f1629;
  --bg-code: #0b0f1e;
  --bg-code-header: rgba(255, 255, 255, 0.02);
  --text-primary: #e8ecf4;
  --text-secondary: #8892a8;
  --text-muted: #4a5568;
  --branch-main: #f59e0b;
  --branch-develop: #3b82f6;
  --branch-feature: #10b981;
  --branch-release: #8b5cf6;
  --branch-hotfix: #ef4444;
  --accent-glow: rgba(59, 130, 246, 0.15);
  --grid-line: rgba(59, 130, 246, 0.06);
  --border-subtle: rgba(136, 146, 168, 0.12);
  --nav-bg: rgba(10, 14, 26, 0.82);
  --row-hover: rgba(255, 255, 255, 0.02);
  --lifetime-bg: rgba(255, 255, 255, 0.03);
  --nav-link-hover-bg: rgba(59, 130, 246, 0.08);
  --nav-link-active-bg: rgba(59, 130, 246, 0.1);
  --tag-bg: rgba(59, 130, 246, 0.1);
  --tag-border: rgba(59, 130, 246, 0.2);
  --page-nav-hover-bg: rgba(59, 130, 246, 0.05);
  --page-nav-hover-border: rgba(59, 130, 246, 0.3);
  --radial-1: rgba(59, 130, 246, 0.04);
  --radial-2: rgba(139, 92, 246, 0.03);
}

html[data-font-size="small"] {
  --font-scale: 0.92;
}

html[data-font-size="large"] {
  --font-scale: 1.1;
}

/* ─── Light Theme ─── */
[data-theme="light"] {
  --bg-deep: #f5f7fb;
  --bg-card: #ffffff;
  --bg-card-hover: #f0f4fa;
  --bg-surface: #eef2f9;
  --bg-code: #1e293b;
  --bg-code-header: rgba(255, 255, 255, 0.05);
  --text-primary: #1a2035;
  --text-secondary: #4b5675;
  --text-muted: #8b95ad;
  --branch-main: #d97706;
  --branch-develop: #2563eb;
  --branch-feature: #059669;
  --branch-release: #7c3aed;
  --branch-hotfix: #dc2626;
  --accent-glow: rgba(59, 130, 246, 0.08);
  --grid-line: rgba(59, 130, 246, 0.04);
  --border-subtle: rgba(59, 130, 246, 0.1);
  --nav-bg: rgba(245, 247, 251, 0.88);
  --row-hover: rgba(59, 130, 246, 0.03);
  --lifetime-bg: rgba(59, 130, 246, 0.05);
  --nav-link-hover-bg: rgba(59, 130, 246, 0.06);
  --nav-link-active-bg: rgba(59, 130, 246, 0.08);
  --tag-bg: rgba(59, 130, 246, 0.08);
  --tag-border: rgba(59, 130, 246, 0.18);
  --page-nav-hover-bg: rgba(59, 130, 246, 0.04);
  --page-nav-hover-border: rgba(59, 130, 246, 0.25);
  --radial-1: rgba(59, 130, 246, 0.03);
  --radial-2: rgba(139, 92, 246, 0.02);
}

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

html {
  scroll-behavior: smooth;
  font-size: calc(16px * var(--font-scale));
}

body {
  font-family: 'Noto Sans JP', sans-serif;
  background: var(--bg-deep);
  color: var(--text-primary);
  line-height: 1.8;
  min-height: 100vh;
  overflow-x: hidden;
}

body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px),
    linear-gradient(0deg, var(--grid-line) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
  z-index: 0;
}

body::after {
  content: '';
  position: fixed;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(ellipse at 30% 20%, var(--radial-1) 0%, transparent 60%),
              radial-gradient(ellipse at 70% 80%, var(--radial-2) 0%, transparent 60%);
  pointer-events: none;
  z-index: 0;
}

/* ─── Navigation ─── */
nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  backdrop-filter: blur(20px) saturate(1.4);
  -webkit-backdrop-filter: blur(20px) saturate(1.4);
  background: var(--nav-bg);
  border-bottom: 1px solid var(--border-subtle);
}

nav .nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  align-items: center;
  height: 64px;
  gap: 3rem;
}

nav .logo {
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-shrink: 0;
}

nav .logo .git-icon {
  width: 28px;
  height: 28px;
  background: linear-gradient(135deg, var(--branch-develop), var(--branch-release));
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  color: #fff;
  font-weight: 700;
}

nav .nav-links {
  display: flex;
  gap: 0.25rem;
  list-style: none;
}

nav .nav-links a {
  font-family: 'Noto Sans JP', sans-serif;
  font-weight: 400;
  font-size: 0.88rem;
  color: var(--text-secondary);
  text-decoration: none;
  padding: 0.5rem 1rem;
  border-radius: 8px;
  transition: all 0.25s ease;
  position: relative;
}

nav .nav-links a:hover {
  color: var(--text-primary);
  background: var(--nav-link-hover-bg);
}

nav .nav-links a.active {
  color: var(--branch-develop);
  background: var(--nav-link-active-bg);
  font-weight: 600;
}

nav .page-indicator {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--text-muted);
  margin-left: 0;
  letter-spacing: 0.05em;
}

/* ─── Main Container ─── */
main {
  position: relative;
  z-index: 1;
  max-width: 1100px;
  margin: 0 auto;
  padding: 100px 2rem 4rem;
}

/* ─── Hero Section ─── */
.hero {
  padding: 3rem 0 4rem;
  text-align: center;
}

.hero .tag {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--branch-develop);
  background: var(--tag-bg);
  border: 1px solid var(--tag-border);
  padding: 0.35rem 1rem;
  border-radius: 99px;
  display: inline-block;
  margin-bottom: 1.5rem;
}

.hero h1 {
  font-size: clamp(2.4rem, 5.5vw, 3.8rem);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: 1.2rem;
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero h1 span {
  background: linear-gradient(135deg, var(--branch-develop), var(--branch-release));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
  font-weight: 300;
  line-height: 1.9;
}

/* ─── Table of Contents ─── */
.toc {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 14px;
  padding: 1.5rem;
  margin: 0 0 4rem;
}

.toc h2 {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  color: var(--text-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}

.toc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.75rem;
}

.toc-grid a {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  min-height: 48px;
  color: var(--text-secondary);
  text-decoration: none;
  border: 1px solid var(--border-subtle);
  border-radius: 10px;
  padding: 0.75rem 1rem;
  font-size: 0.9rem;
  font-weight: 500;
  transition: all 0.25s ease;
}

.toc-grid a:hover {
  color: var(--text-primary);
  border-color: var(--page-nav-hover-border);
  background: var(--nav-link-hover-bg);
}

.toc-grid span {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--branch-develop);
  background: var(--tag-bg);
  border: 1px solid var(--tag-border);
  border-radius: 6px;
  padding: 0.15rem 0.4rem;
  flex-shrink: 0;
}

section[id] {
  scroll-margin-top: 88px;
}

/* ─── Section Headers ─── */
.section-header {
  margin-bottom: 2.5rem;
}

.section-header .num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  color: var(--branch-develop);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 0.6rem;
  display: block;
}

.section-header h2 {
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.3;
}

/* ─── Cards ─── */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.25rem;
  margin-bottom: 4rem;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 14px;
  padding: 2rem;
  transition: all 0.35s ease;
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--card-accent, var(--branch-develop));
  opacity: 0;
  transition: opacity 0.35s ease;
}

.card:hover {
  background: var(--bg-card-hover);
  border-color: rgba(136, 146, 168, 0.2);
  transform: translateY(-2px);
}

.card:hover::before {
  opacity: 1;
}

.card .card-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  margin-bottom: 1.2rem;
  background: var(--card-accent-bg, rgba(59, 130, 246, 0.1));
  color: var(--card-accent, var(--branch-develop));
}

.card h3 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 0.7rem;
  letter-spacing: -0.01em;
}

.card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.75;
  font-weight: 300;
}

/* ─── Branch Diagram ─── */
.branch-diagram {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 16px;
  padding: 3rem 2.5rem;
  margin-bottom: 4rem;
  position: relative;
  overflow: hidden;
}

.branch-diagram::after {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  width: 200px;
  height: 200px;
  background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
  pointer-events: none;
}

.branch-diagram h3 {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 2rem;
}

.branch-visual {
  display: flex;
  flex-direction: column;
  gap: 1.1rem;
  position: relative;
}

.branch-row {
  display: flex;
  align-items: center;
  gap: 1.2rem;
  padding: 0.8rem 1rem;
  border-radius: 10px;
  transition: background 0.25s ease;
}

.branch-row:hover {
  background: var(--row-hover);
}

.branch-dot {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  flex-shrink: 0;
  position: relative;
  box-shadow: 0 0 12px currentColor;
}

.branch-line-segment {
  width: 40px;
  height: 2px;
  flex-shrink: 0;
}

.branch-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82rem;
  font-weight: 600;
  min-width: 120px;
}

.branch-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-weight: 300;
}

/* Branch Colors */
.branch-main .branch-dot,
.branch-main .branch-line-segment { background: var(--branch-main); color: var(--branch-main); }
.branch-main .branch-label { color: var(--branch-main); }

.branch-develop .branch-dot,
.branch-develop .branch-line-segment { background: var(--branch-develop); color: var(--branch-develop); }
.branch-develop .branch-label { color: var(--branch-develop); }

.branch-feature .branch-dot,
.branch-feature .branch-line-segment { background: var(--branch-feature); color: var(--branch-feature); }
.branch-feature .branch-label { color: var(--branch-feature); }

.branch-release .branch-dot,
.branch-release .branch-line-segment { background: var(--branch-release); color: var(--branch-release); }
.branch-release .branch-label { color: var(--branch-release); }

.branch-hotfix .branch-dot,
.branch-hotfix .branch-line-segment { background: var(--branch-hotfix); color: var(--branch-hotfix); }
.branch-hotfix .branch-label { color: var(--branch-hotfix); }

/* ─── Branch Detail Cards ─── */
.branch-detail {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 14px;
  padding: 2rem 2.5rem;
  margin-bottom: 1.5rem;
  border-left: 3px solid var(--card-accent, var(--branch-develop));
  transition: all 0.3s ease;
}

.branch-detail:hover {
  background: var(--bg-card-hover);
  transform: translateX(4px);
}

.branch-detail h3 {
  font-family: 'JetBrains Mono', monospace;
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.3rem;
  color: var(--card-accent, var(--text-primary));
}

.branch-detail .branch-naming {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem;
  color: var(--text-muted);
  margin-bottom: 0.8rem;
}

.branch-detail p {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.8;
  font-weight: 300;
}

.branch-detail .lifetime {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--text-muted);
  background: var(--lifetime-bg);
  padding: 0.3rem 0.7rem;
  border-radius: 6px;
  margin-top: 0.8rem;
}

/* ─── Code Block ─── */
.code-block {
  background: var(--bg-code);
  border: 1px solid var(--border-subtle);
  border-radius: 12px;
  margin-bottom: 1.5rem;
  overflow: hidden;
}

.code-block .code-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.8rem 1.2rem;
  background: var(--bg-code-header);
  border-bottom: 1px solid var(--border-subtle);
}

.code-block .code-header .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.code-block .code-header .dot:nth-child(1) { background: #ef4444; }
.code-block .code-header .dot:nth-child(2) { background: #f59e0b; }
.code-block .code-header .dot:nth-child(3) { background: #10b981; }

.code-block .code-header .code-title {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--text-muted);
  margin-left: 0.5rem;
}

.code-block pre {
  padding: 1.5rem;
  overflow-x: auto;
}

.code-block code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82rem;
  line-height: 1.9;
  color: var(--text-secondary);
}

.code-block code .cmd {
  color: var(--branch-develop);
}

.code-block code .flag {
  color: var(--branch-release);
}

.code-block code .string {
  color: var(--branch-feature);
}

.code-block code .comment {
  color: var(--text-muted);
  font-style: italic;
}

/* ─── Step Flow ─── */
.step-flow {
  margin-bottom: 4rem;
}

.step {
  display: flex;
  gap: 2rem;
  margin-bottom: 2.5rem;
  position: relative;
}

.step::before {
  content: '';
  position: absolute;
  left: 22px;
  top: 50px;
  bottom: -2.5rem;
  width: 2px;
  background: linear-gradient(to bottom, var(--border-subtle), transparent);
}

.step:last-child::before {
  display: none;
}

.step .step-num {
  width: 46px;
  height: 46px;
  border-radius: 12px;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--branch-develop);
  flex-shrink: 0;
  z-index: 1;
}

.step .step-content {
  flex: 1;
  padding-top: 0.3rem;
}

.step .step-content h3 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  letter-spacing: -0.01em;
}

.step .step-content p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  font-weight: 300;
  line-height: 1.8;
  margin-bottom: 1rem;
}

/* ─── Flow Diagram (SVG) ─── */
.flow-svg-container {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: 16px;
  padding: 2.5rem;
  margin-bottom: 4rem;
  overflow-x: auto;
}

.flow-svg-container h3 {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 2rem;
}

/* ─── Page Navigation ─── */
.page-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 2rem 0;
  margin-top: 2rem;
  border-top: 1px solid var(--border-subtle);
}

.page-nav a {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
  padding: 0.8rem 1.5rem;
  border-radius: 10px;
  border: 1px solid var(--border-subtle);
  transition: all 0.3s ease;
}

.page-nav a:hover {
  color: var(--branch-develop);
  border-color: var(--page-nav-hover-border);
  background: var(--page-nav-hover-bg);
}

.page-nav a .nav-label {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.68rem;
  color: var(--text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.page-nav a .nav-title {
  display: block;
}

.page-nav .spacer {
  flex: 1;
}

/* ─── Footer ─── */
footer {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 3rem 2rem;
  font-size: 0.78rem;
  color: var(--text-muted);
  font-family: 'JetBrains Mono', monospace;
  letter-spacing: 0.03em;
}

/* ─── Theme Toggle ─── */
.theme-toggle {
  margin-left: auto;
  background: none;
  border: 1px solid var(--border-subtle);
  border-radius: 8px;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--text-secondary);
  font-size: 1.1rem;
  transition: all 0.3s ease;
  flex-shrink: 0;
}

.theme-toggle:hover {
  color: var(--branch-develop);
  border-color: var(--page-nav-hover-border);
  background: var(--nav-link-hover-bg);
}

.theme-toggle .icon-sun,
.theme-toggle .icon-moon {
  display: none;
}

:root .theme-toggle .icon-sun { display: block; }
:root .theme-toggle .icon-moon { display: none; }
[data-theme="light"] .theme-toggle .icon-sun { display: none; }
[data-theme="light"] .theme-toggle .icon-moon { display: block; }

/* ─── Font Size Controls ─── */
.font-controls {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.2rem;
  border: 1px solid var(--border-subtle);
  border-radius: 10px;
  flex-shrink: 0;
}

.font-controls button {
  min-width: 34px;
  height: 32px;
  border: 0;
  border-radius: 7px;
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.76rem;
  font-weight: 700;
  transition: all 0.25s ease;
}

.font-controls button:hover {
  color: var(--text-primary);
  background: var(--nav-link-hover-bg);
}

.font-controls button.active {
  color: var(--branch-develop);
  background: var(--nav-link-active-bg);
}

/* ─── Light mode: keep code blocks readable ─── */
[data-theme="light"] .code-block code {
  color: #c9d1d9;
}

[data-theme="light"] .code-block code .cmd {
  color: #79c0ff;
}

[data-theme="light"] .code-block code .flag {
  color: #d2a8ff;
}

[data-theme="light"] .code-block code .string {
  color: #7ee787;
}

[data-theme="light"] .code-block code .comment {
  color: #6e7681;
}

[data-theme="light"] .code-block .code-header .code-title {
  color: #6e7681;
}

[data-theme="light"] .card:hover {
  border-color: rgba(59, 130, 246, 0.15);
}

[data-theme="light"] .branch-detail:hover {
  background: var(--bg-card-hover);
}

[data-theme="light"] .branch-dot {
  box-shadow: 0 0 8px currentColor;
}

/* ─── Utilities ─── */
.mb-6 { margin-bottom: 4rem; }

/* ─── Hamburger Button ─── */
.hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  padding: 8px;
  background: none;
  border: 1px solid var(--border-subtle);
  border-radius: 8px;
  cursor: pointer;
  flex-shrink: 0;
  transition: all 0.3s ease;
}

.hamburger:hover {
  border-color: var(--page-nav-hover-border);
  background: var(--nav-link-hover-bg);
}

.hamburger span {
  display: block;
  width: 100%;
  height: 2px;
  background: var(--text-secondary);
  border-radius: 2px;
  transition: all 0.3s ease;
}

.hamburger.active span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.hamburger.active span:nth-child(2) {
  opacity: 0;
}

.hamburger.active span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ─── Mobile Menu Overlay ─── */
.nav-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 99;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.nav-overlay.active {
  opacity: 1;
}

/* ─── Responsive ─── */
@media (max-width: 768px) {
  .hamburger {
    display: flex;
  }

  nav .nav-inner {
    padding: 0 1rem;
    gap: 1rem;
  }

  nav .nav-links {
    position: fixed;
    top: 64px;
    right: -280px;
    width: 280px;
    height: calc(100vh - 64px);
    background: var(--bg-card);
    border-left: 1px solid var(--border-subtle);
    flex-direction: column;
    gap: 0;
    padding: 1rem 0;
    overflow-y: auto;
    transition: right 0.3s ease;
    z-index: 101;
  }

  nav .nav-links.open {
    right: 0;
  }

  nav .nav-links a {
    font-size: 0.92rem;
    padding: 0.9rem 1.5rem;
    border-radius: 0;
    display: block;
  }

  nav .nav-links a:hover {
    background: var(--nav-link-hover-bg);
  }

  nav .nav-links a.active {
    border-left: 3px solid var(--branch-develop);
  }

  nav .page-indicator {
    display: none;
  }

  .nav-overlay.active {
    display: block;
  }

  main {
    padding: 88px 1.2rem 3rem;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .card-grid {
    grid-template-columns: 1fr;
  }

  .step {
    gap: 1.2rem;
  }

  .branch-row {
    flex-wrap: wrap;
  }

  .branch-desc {
    width: 100%;
    padding-left: 56px;
    margin-top: -0.3rem;
  }

  .page-nav {
    flex-direction: column;
    gap: 1rem;
  }

  .page-nav a {
    width: 100%;
    justify-content: center;
  }
}

/* ─── Animations ─── */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero,
.card,
.branch-diagram,
.branch-detail,
.code-block,
.step,
.flow-svg-container {
  animation: fadeInUp 0.6s ease both;
}

.card:nth-child(1) { animation-delay: 0.05s; }
.card:nth-child(2) { animation-delay: 0.12s; }
.card:nth-child(3) { animation-delay: 0.19s; }
.card:nth-child(4) { animation-delay: 0.26s; }

.branch-detail:nth-child(2) { animation-delay: 0.08s; }
.branch-detail:nth-child(3) { animation-delay: 0.16s; }
.branch-detail:nth-child(4) { animation-delay: 0.24s; }
.branch-detail:nth-child(5) { animation-delay: 0.32s; }
.branch-detail:nth-child(6) { animation-delay: 0.40s; }

.step:nth-child(1) { animation-delay: 0.05s; }
.step:nth-child(2) { animation-delay: 0.12s; }
.step:nth-child(3) { animation-delay: 0.19s; }
.step:nth-child(4) { animation-delay: 0.24s; }
.step:nth-child(5) { animation-delay: 0.30s; }
.step:nth-child(6) { animation-delay: 0.36s; }
.step:nth-child(7) { animation-delay: 0.42s; }