/* ============================================================
   DESIGN TOKENS & CSS VARIABLES
   ============================================================ */
:root {
  /* Colors - Light Mode */
  --color-bg:          #ffffff;
  --color-bg-alt:      #f8fafc;
  --color-bg-card:     #ffffff;
  --color-border:      #e2e8f0;
  --color-border-soft: #f1f5f9;

  --color-text-primary:   #0f172a;
  --color-text-secondary: #475569;
  --color-text-muted:     #94a3b8;

  --color-accent:       #6366f1;
  --color-accent-light: #eef2ff;
  --color-accent-hover: #4f46e5;
  --color-accent-dark:  #3730a3;

  --color-success:      #10b981;
  --color-success-bg:   #ecfdf5;
  --color-warning:      #f59e0b;
  --color-warning-bg:   #fffbeb;
  --color-danger:       #ef4444;
  --color-danger-bg:    #fef2f2;
  --color-info:         #3b82f6;
  --color-info-bg:      #eff6ff;

  --color-code-bg:      #1e293b;
  --color-code-text:    #e2e8f0;

  /* Sidebar */
  --sidebar-width:      280px;
  --sidebar-bg:         #f8fafc;
  --sidebar-border:     #e2e8f0;

  /* Typography */
  --font-sans:   'Inter', system-ui, -apple-system, sans-serif;
  --font-mono:   'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;

  --text-xs:    0.75rem;
  --text-sm:    0.875rem;
  --text-base:  1rem;
  --text-lg:    1.125rem;
  --text-xl:    1.25rem;
  --text-2xl:   1.5rem;
  --text-3xl:   1.875rem;
  --text-4xl:   2.25rem;

  /* Spacing (8dp grid) */
  --sp-1:  4px;
  --sp-2:  8px;
  --sp-3:  12px;
  --sp-4:  16px;
  --sp-5:  20px;
  --sp-6:  24px;
  --sp-8:  32px;
  --sp-10: 40px;
  --sp-12: 48px;
  --sp-16: 64px;

  /* Shadows */
  --shadow-sm:  0 1px 2px rgba(0,0,0,.05);
  --shadow:     0 1px 3px rgba(0,0,0,.1), 0 1px 2px rgba(0,0,0,.06);
  --shadow-md:  0 4px 6px rgba(0,0,0,.07), 0 2px 4px rgba(0,0,0,.05);
  --shadow-lg:  0 10px 15px rgba(0,0,0,.1), 0 4px 6px rgba(0,0,0,.05);

  /* Radius */
  --radius-sm:  4px;
  --radius:     8px;
  --radius-md:  10px;
  --radius-lg:  16px;
  --radius-xl:  20px;
  --radius-full:9999px;

  /* Transitions */
  --transition: 150ms ease;
  --transition-md: 250ms ease;

  /* Header */
  --header-height: 64px;
}

/* ============================================================
   DARK MODE TOKENS
   ============================================================ */
[data-theme="dark"] {
  --color-bg:          #0f172a;
  --color-bg-alt:      #1e293b;
  --color-bg-card:     #1e293b;
  --color-border:      #334155;
  --color-border-soft: #1e293b;

  --color-text-primary:   #f1f5f9;
  --color-text-secondary: #94a3b8;
  --color-text-muted:     #64748b;

  --color-accent:       #818cf8;
  --color-accent-light: #1e1b4b;
  --color-accent-hover: #a5b4fc;
  --color-accent-dark:  #c7d2fe;

  --color-success-bg:   #064e3b;
  --color-warning-bg:   #78350f;
  --color-danger-bg:    #7f1d1d;
  --color-info-bg:      #1e3a5f;

  --color-code-bg:      #0d1117;
  --color-code-text:    #e6edf3;

  --sidebar-bg:         #1e293b;
  --sidebar-border:     #334155;

  --shadow-sm:  0 1px 2px rgba(0,0,0,.3);
  --shadow:     0 1px 3px rgba(0,0,0,.4), 0 1px 2px rgba(0,0,0,.3);
  --shadow-md:  0 4px 6px rgba(0,0,0,.4);
  --shadow-lg:  0 10px 15px rgba(0,0,0,.5);
}

/* ============================================================
   RESET & BASE
   ============================================================ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-text-primary);
  background-color: var(--color-bg);
  transition: background-color var(--transition-md), color var(--transition-md);
  overflow-x: hidden;
}

/* Skip link for keyboard accessibility */
.skip-link {
  position: absolute;
  top: -999px; left: 0;
  z-index: 9999;
  padding: var(--sp-2) var(--sp-4);
  background: var(--color-accent);
  color: #fff;
  font-weight: 600;
  border-radius: var(--radius);
  text-decoration: none;
  transition: top var(--transition);
}
.skip-link:focus { top: var(--sp-4); outline: 2px solid #fff; outline-offset: 2px; }

img, video { max-width: 100%; height: auto; display: block; }
a { color: var(--color-accent); text-decoration: none; }
a:hover { color: var(--color-accent-hover); text-decoration: underline; }

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

/* ============================================================
   LAYOUT SHELL
   ============================================================ */
.layout {
  display: flex;
  min-height: 100vh;
}

/* ============================================================
   HEADER
   ============================================================ */
.header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-height);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  padding: 0 var(--sp-6);
  gap: var(--sp-4);
  z-index: 100;
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  background-color: color-mix(in srgb, var(--color-bg) 85%, transparent);
  box-shadow: var(--shadow-sm);
}

.header__logo {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  font-weight: 700;
  font-size: var(--text-lg);
  color: var(--color-text-primary);
  text-decoration: none;
  white-space: nowrap;
  min-width: 180px;
  flex-shrink: 0;
}
.header__logo:hover { text-decoration: none; color: var(--color-accent); }

.header__logo-icon {
  width: 34px; height: 34px;
  background: linear-gradient(135deg, var(--color-accent), #a855f7);
  border-radius: var(--radius);
  display: flex; align-items: center; justify-content: center;
  color: #fff;
  font-size: var(--text-lg);
  flex-shrink: 0;
}

.header__search {
  flex: 1;
  max-width: 480px;
}

.header__search-input {
  width: 100%;
  height: 40px;
  padding: 0 var(--sp-4) 0 40px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  background: var(--color-bg-alt);
  color: var(--color-text-primary);
  font-size: var(--text-sm);
  font-family: var(--font-sans);
  transition: border-color var(--transition), box-shadow var(--transition);
}
.header__search-input::placeholder { color: var(--color-text-muted); }
.header__search-input:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-accent) 20%, transparent);
}

.header__search-wrap {
  position: relative;
}
.header__search-wrap svg {
  position: absolute; left: 12px; top: 50%;
  transform: translateY(-50%);
  color: var(--color-text-muted);
  pointer-events: none;
}

.header__actions {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  margin-left: auto;
}

.btn-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px; height: 40px;
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  background: var(--color-bg-alt);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: background var(--transition), color var(--transition), border-color var(--transition);
  position: relative;
}
.btn-icon:hover {
  background: var(--color-bg);
  color: var(--color-text-primary);
  border-color: var(--color-accent);
}
.btn-icon:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; }

.hamburger {
  display: none;
}

.version-badge {
  font-size: var(--text-xs);
  font-weight: 600;
  padding: 2px 8px;
  border-radius: var(--radius-full);
  background: var(--color-accent-light);
  color: var(--color-accent);
  white-space: nowrap;
}

/* ============================================================
   SIDEBAR
   ============================================================ */
.sidebar {
  position: fixed;
  top: var(--header-height);
  left: 0;
  width: var(--sidebar-width);
  height: calc(100vh - var(--header-height));
  background: var(--sidebar-bg);
  border-right: 1px solid var(--sidebar-border);
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--sp-6) 0 var(--sp-8);
  z-index: 90;
  transition: transform var(--transition-md);
}
.sidebar::-webkit-scrollbar { width: 4px; }
.sidebar::-webkit-scrollbar-thumb { background: var(--color-border); border-radius: var(--radius-full); }

.sidebar__section { margin-bottom: var(--sp-6); }

.sidebar__label {
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  padding: 0 var(--sp-6);
  margin-bottom: var(--sp-2);
}

.sidebar__nav { list-style: none; }

.sidebar__nav-item a {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  padding: var(--sp-2) var(--sp-6);
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  text-decoration: none;
  border-radius: 0;
  transition: background var(--transition), color var(--transition);
  position: relative;
  min-height: 44px;
}
.sidebar__nav-item a:hover {
  background: color-mix(in srgb, var(--color-accent) 8%, transparent);
  color: var(--color-accent);
  text-decoration: none;
}
.sidebar__nav-item a.active {
  background: var(--color-accent-light);
  color: var(--color-accent);
  font-weight: 600;
}
.sidebar__nav-item a.active::before {
  content: '';
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 3px;
  background: var(--color-accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}
.sidebar__nav-item a svg { flex-shrink: 0; }

.sidebar__badge {
  margin-left: auto;
  font-size: 10px;
  font-weight: 700;
  padding: 2px 6px;
  border-radius: var(--radius-full);
  background: var(--color-success);
  color: #fff;
}
.sidebar__badge--new { background: var(--color-accent); }
.sidebar__badge--beta { background: var(--color-warning); color: var(--color-text-primary); }

.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.4);
  z-index: 89;
  backdrop-filter: blur(2px);
}

/* ============================================================
   MAIN CONTENT
   ============================================================ */
.main {
  margin-left: var(--sidebar-width);
  margin-top: var(--header-height);
  flex: 1;
  min-width: 0;
}

.content {
  max-width: 860px;
  margin: 0 auto;
  padding: var(--sp-10) var(--sp-8) var(--sp-16);
}

/* ============================================================
   TABLE OF CONTENTS (right side)
   ============================================================ */
.toc {
  position: fixed;
  top: calc(var(--header-height) + var(--sp-8));
  right: var(--sp-6);
  width: 220px;
  font-size: var(--text-sm);
  display: none;
}
.toc__title {
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--color-text-muted);
  margin-bottom: var(--sp-3);
}
.toc__list { list-style: none; }
.toc__list li { margin-bottom: var(--sp-1); }
.toc__list a {
  display: block;
  padding: var(--sp-1) var(--sp-2);
  color: var(--color-text-muted);
  text-decoration: none;
  border-left: 2px solid var(--color-border);
  transition: color var(--transition), border-color var(--transition);
  line-height: 1.4;
}
.toc__list a:hover { color: var(--color-text-secondary); border-color: var(--color-text-muted); text-decoration: none; }
.toc__list a.active { color: var(--color-accent); border-color: var(--color-accent); font-weight: 600; }
.toc__list .toc-h3 { padding-left: var(--sp-4); font-size: var(--text-xs); }

/* ============================================================
   TYPOGRAPHY
   ============================================================ */
.page-header { margin-bottom: var(--sp-8); }

.page-title {
  font-size: var(--text-4xl);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -.03em;
  color: var(--color-text-primary);
  margin-bottom: var(--sp-4);
}

.page-subtitle {
  font-size: var(--text-xl);
  color: var(--color-text-secondary);
  line-height: 1.5;
  max-width: 640px;
}

.page-meta {
  display: flex;
  align-items: center;
  gap: var(--sp-4);
  flex-wrap: wrap;
  margin-top: var(--sp-4);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}
.page-meta__dot { width: 4px; height: 4px; border-radius: 50%; background: var(--color-border); }

h2.section-title {
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--color-text-primary);
  margin: var(--sp-10) 0 var(--sp-4);
  padding-bottom: var(--sp-3);
  border-bottom: 1px solid var(--color-border);
  scroll-margin-top: calc(var(--header-height) + 24px);
}

h3.subsection-title {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--color-text-primary);
  margin: var(--sp-6) 0 var(--sp-3);
  scroll-margin-top: calc(var(--header-height) + 24px);
}

p { margin-bottom: var(--sp-4); color: var(--color-text-secondary); line-height: 1.75; }
p:last-child { margin-bottom: 0; }

strong { color: var(--color-text-primary); font-weight: 600; }

/* ============================================================
   BREADCRUMB
   ============================================================ */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-bottom: var(--sp-6);
  flex-wrap: wrap;
}
.breadcrumb a { color: var(--color-text-muted); transition: color var(--transition); }
.breadcrumb a:hover { color: var(--color-accent); text-decoration: none; }
.breadcrumb__sep { color: var(--color-border); }
.breadcrumb__current { color: var(--color-text-secondary); font-weight: 500; }

/* ============================================================
   CODE BLOCKS
   ============================================================ */
code {
  font-family: var(--font-mono);
  font-size: .875em;
  background: var(--color-bg-alt);
  padding: 1px 6px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  color: var(--color-accent);
}

pre {
  background: var(--color-code-bg);
  border-radius: var(--radius-md);
  overflow: hidden;
  margin: var(--sp-6) 0;
  box-shadow: var(--shadow-md);
}

pre code {
  display: block;
  padding: var(--sp-5) var(--sp-6);
  background: none;
  border: none;
  color: var(--color-code-text);
  font-size: var(--text-sm);
  line-height: 1.7;
  overflow-x: auto;
}

.code-block {
  position: relative;
}

.code-block__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--sp-3) var(--sp-5);
  background: color-mix(in srgb, #fff 8%, var(--color-code-bg));
  border-bottom: 1px solid rgba(255,255,255,.08);
}
.code-block__lang {
  font-size: var(--text-xs);
  font-weight: 600;
  color: rgba(255,255,255,.5);
  text-transform: uppercase;
  letter-spacing: .06em;
  font-family: var(--font-mono);
}
.code-block__dots {
  display: flex;
  gap: 6px;
}
.code-block__dot {
  width: 12px; height: 12px;
  border-radius: 50%;
}
.code-block__dot:nth-child(1) { background: #ff5f57; }
.code-block__dot:nth-child(2) { background: #ffbd2e; }
.code-block__dot:nth-child(3) { background: #28ca41; }

.code-copy-btn {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  padding: var(--sp-1) var(--sp-3);
  font-size: var(--text-xs);
  font-weight: 500;
  color: rgba(255,255,255,.5);
  background: rgba(255,255,255,.06);
  border: 1px solid rgba(255,255,255,.1);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
  font-family: var(--font-sans);
  min-height: 28px;
}
.code-copy-btn:hover { background: rgba(255,255,255,.12); color: rgba(255,255,255,.8); }
.code-copy-btn.copied { color: #28ca41; border-color: #28ca41; }

/* Syntax highlight colors */
.kw { color: #c792ea; }  /* keyword */
.st { color: #c3e88d; }  /* string */
.cm { color: #546e7a; font-style: italic; } /* comment */
.fn { color: #82aaff; }  /* function */
.nm { color: #f78c6c; }  /* number/const */
.tp { color: #ffcb6b; }  /* type */
.op { color: #89ddff; }  /* operator */
.at { color: #f07178; }  /* attr */

/* ============================================================
   CALLOUTS / ALERTS
   ============================================================ */
.callout {
  display: flex;
  gap: var(--sp-4);
  padding: var(--sp-4) var(--sp-5);
  border-radius: var(--radius-md);
  margin: var(--sp-6) 0;
  border: 1px solid transparent;
}
.callout__icon {
  width: 24px; height: 24px;
  flex-shrink: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: var(--text-lg);
  margin-top: 1px;
}
.callout__content { flex: 1; min-width: 0; }
.callout__title { font-weight: 700; margin-bottom: var(--sp-1); font-size: var(--text-sm); }
.callout__body { font-size: var(--text-sm); line-height: 1.6; color: inherit; margin: 0; }

.callout--info    { background: var(--color-info-bg);    color: var(--color-info);    border-color: var(--color-info); }
.callout--success { background: var(--color-success-bg); color: var(--color-success); border-color: var(--color-success); }
.callout--warning { background: var(--color-warning-bg); color: var(--color-warning); border-color: var(--color-warning); }
.callout--danger  { background: var(--color-danger-bg);  color: var(--color-danger);  border-color: var(--color-danger); }

/* ============================================================
   TABLES
   ============================================================ */
.table-wrapper {
  overflow-x: auto;
  margin: var(--sp-6) 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
}
thead { background: var(--color-bg-alt); }
th {
  padding: var(--sp-3) var(--sp-4);
  text-align: left;
  font-weight: 600;
  color: var(--color-text-primary);
  font-size: var(--text-xs);
  text-transform: uppercase;
  letter-spacing: .06em;
  border-bottom: 1px solid var(--color-border);
}
td {
  padding: var(--sp-3) var(--sp-4);
  border-bottom: 1px solid var(--color-border-soft);
  color: var(--color-text-secondary);
  vertical-align: top;
}
tr:last-child td { border-bottom: none; }
tr:hover td { background: color-mix(in srgb, var(--color-accent) 4%, transparent); }

/* ============================================================
   CARDS
   ============================================================ */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--sp-4);
  margin: var(--sp-6) 0;
}

.card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--sp-5);
  transition: border-color var(--transition), box-shadow var(--transition), transform var(--transition-md);
  text-decoration: none;
  display: block;
}
.card:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
  text-decoration: none;
}
.card__icon {
  width: 44px; height: 44px;
  border-radius: var(--radius);
  background: var(--color-accent-light);
  display: flex; align-items: center; justify-content: center;
  font-size: 22px;
  margin-bottom: var(--sp-4);
}
.card__title {
  font-weight: 700;
  font-size: var(--text-base);
  color: var(--color-text-primary);
  margin-bottom: var(--sp-2);
}
.card__desc {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin: 0;
}

/* ============================================================
   STEPS
   ============================================================ */
.steps { margin: var(--sp-6) 0; counter-reset: step; }
.step {
  display: flex;
  gap: var(--sp-4);
  padding: var(--sp-5) 0;
  border-bottom: 1px solid var(--color-border-soft);
  counter-increment: step;
}
.step:last-child { border-bottom: none; }
.step__num {
  width: 36px; height: 36px;
  border-radius: 50%;
  background: var(--color-accent-light);
  color: var(--color-accent);
  font-size: var(--text-sm);
  font-weight: 700;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
}
.step__num::before { content: counter(step); }
.step__body {}
.step__title { font-weight: 600; font-size: var(--text-base); color: var(--color-text-primary); margin-bottom: var(--sp-2); }
.step__desc { font-size: var(--text-sm); color: var(--color-text-secondary); line-height: 1.65; margin: 0; }

/* ============================================================
   BADGES / TAGS
   ============================================================ */
.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-1);
  padding: 2px 10px;
  border-radius: var(--radius-full);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: .03em;
}
.badge--default  { background: var(--color-bg-alt);      color: var(--color-text-secondary); border: 1px solid var(--color-border); }
.badge--accent   { background: var(--color-accent-light); color: var(--color-accent); }
.badge--success  { background: var(--color-success-bg);   color: var(--color-success); }
.badge--warning  { background: var(--color-warning-bg);   color: var(--color-warning); }
.badge--danger   { background: var(--color-danger-bg);    color: var(--color-danger); }

/* ============================================================
   BUTTONS
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--sp-2);
  padding: 0 var(--sp-5);
  height: 44px;
  border-radius: var(--radius);
  font-size: var(--text-sm);
  font-weight: 600;
  cursor: pointer;
  border: 1px solid transparent;
  transition: background var(--transition), color var(--transition), box-shadow var(--transition), border-color var(--transition), transform var(--transition);
  text-decoration: none;
  white-space: nowrap;
  font-family: var(--font-sans);
  line-height: 1;
  touch-action: manipulation;
}
.btn:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; }
.btn:active { transform: scale(0.98); }

.btn--primary {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
  box-shadow: 0 1px 2px rgba(99,102,241,.3);
}
.btn--primary:hover { background: var(--color-accent-hover); border-color: var(--color-accent-hover); box-shadow: 0 4px 12px rgba(99,102,241,.4); text-decoration: none; color: #fff; }

.btn--secondary {
  background: transparent;
  color: var(--color-accent);
  border-color: var(--color-accent);
}
.btn--secondary:hover { background: var(--color-accent-light); text-decoration: none; }

.btn--ghost {
  background: transparent;
  color: var(--color-text-secondary);
  border-color: var(--color-border);
}
.btn--ghost:hover { background: var(--color-bg-alt); color: var(--color-text-primary); text-decoration: none; }

.btn--sm { height: 36px; padding: 0 var(--sp-4); font-size: var(--text-xs); }
.btn--lg { height: 52px; padding: 0 var(--sp-8); font-size: var(--text-base); }

/* ============================================================
   HERO SECTION (Home page)
   ============================================================ */
.hero {
  text-align: center;
  padding: var(--sp-10) var(--sp-6) var(--sp-8);
  background: linear-gradient(135deg, var(--color-accent-light) 0%, var(--color-bg) 60%);
  border-radius: var(--radius-xl);
  margin-bottom: var(--sp-10);
  border: 1px solid var(--color-border);
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  top: -60px; right: -60px;
  width: 240px; height: 240px;
  background: radial-gradient(circle, color-mix(in srgb, var(--color-accent) 20%, transparent) 0%, transparent 70%);
  pointer-events: none;
}
.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  margin-bottom: var(--sp-5);
}
.hero__title {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 900;
  letter-spacing: -.04em;
  line-height: 1.1;
  color: var(--color-text-primary);
  margin-bottom: var(--sp-5);
}
.hero__title span {
  background: linear-gradient(135deg, var(--color-accent), #a855f7);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero__subtitle {
  font-size: var(--text-xl);
  color: var(--color-text-secondary);
  max-width: 560px;
  margin: 0 auto var(--sp-8);
  line-height: 1.55;
}
.hero__actions {
  display: flex;
  gap: var(--sp-3);
  justify-content: center;
  flex-wrap: wrap;
}

/* ============================================================
   TABS
   ============================================================ */
.tabs { margin: var(--sp-6) 0; }
.tabs__list {
  display: flex;
  gap: 2px;
  border-bottom: 2px solid var(--color-border);
  overflow-x: auto;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}
.tabs__list::-webkit-scrollbar { display: none; }
.tab-btn {
  padding: var(--sp-3) var(--sp-5);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  cursor: pointer;
  border: none;
  background: none;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: color var(--transition), border-color var(--transition);
  white-space: nowrap;
  min-height: 44px;
  font-family: var(--font-sans);
}
.tab-btn:hover { color: var(--color-text-secondary); }
.tab-btn.active { color: var(--color-accent); border-bottom-color: var(--color-accent); font-weight: 600; }
.tab-btn:focus-visible { outline: 2px solid var(--color-accent); outline-offset: -2px; border-radius: var(--radius-sm) var(--radius-sm) 0 0; }

.tab-panel { display: none; padding: var(--sp-5) 0; }
.tab-panel.active { display: block; }

/* ============================================================
   PAGINATION / PREV-NEXT
   ============================================================ */
.page-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-4);
  margin-top: var(--sp-12);
  padding-top: var(--sp-6);
  border-top: 1px solid var(--color-border);
}
.page-nav__link {
  display: flex;
  flex-direction: column;
  gap: var(--sp-1);
  padding: var(--sp-4);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  text-decoration: none;
  transition: border-color var(--transition), background var(--transition);
}
.page-nav__link:hover { border-color: var(--color-accent); background: var(--color-accent-light); text-decoration: none; }
.page-nav__link--next { text-align: right; }
.page-nav__dir { font-size: var(--text-xs); color: var(--color-text-muted); font-weight: 500; }
.page-nav__title { font-size: var(--text-sm); font-weight: 600; color: var(--color-text-primary); }

/* ============================================================
   SEARCH MODAL
   ============================================================ */
.search-modal {
  position: fixed; inset: 0;
  z-index: 200;
  display: none;
  align-items: flex-start;
  justify-content: center;
  padding: 80px var(--sp-4) var(--sp-4);
}
.search-modal.open { display: flex; }
.search-modal__backdrop {
  position: fixed; inset: 0;
  background: rgba(0,0,0,.5);
  backdrop-filter: blur(4px);
}
.search-modal__box {
  position: relative;
  width: 100%;
  max-width: 560px;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
  z-index: 1;
}
.search-modal__input-wrap {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  padding: var(--sp-4);
  border-bottom: 1px solid var(--color-border);
}
.search-modal__input {
  flex: 1;
  border: none;
  background: none;
  font-size: var(--text-base);
  color: var(--color-text-primary);
  font-family: var(--font-sans);
}
.search-modal__input:focus { outline: none; }
.search-modal__input::placeholder { color: var(--color-text-muted); }
.search-modal__results { padding: var(--sp-4); max-height: 360px; overflow-y: auto; }
.search-result {
  display: block;
  padding: var(--sp-3) var(--sp-4);
  border-radius: var(--radius);
  text-decoration: none;
  transition: background var(--transition);
  cursor: pointer;
}
.search-result:hover { background: var(--color-bg-alt); text-decoration: none; }
.search-result__title { font-weight: 600; font-size: var(--text-sm); color: var(--color-text-primary); }
.search-result__desc { font-size: var(--text-xs); color: var(--color-text-muted); margin-top: 2px; }
.search-modal__footer {
  padding: var(--sp-3) var(--sp-4);
  border-top: 1px solid var(--color-border);
  display: flex;
  gap: var(--sp-4);
  font-size: var(--text-xs);
  color: var(--color-text-muted);
}
.kbd {
  display: inline-flex; align-items: center;
  padding: 1px 5px;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-text-secondary);
}

/* ============================================================
   FOOTER
   ============================================================ */
.doc-footer {
  margin-top: var(--sp-12);
  padding: var(--sp-6) 0 0;
  border-top: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--sp-4);
}
.doc-footer__edit {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  text-decoration: none;
  transition: color var(--transition);
}
.doc-footer__edit:hover { color: var(--color-accent); text-decoration: none; }
.doc-footer__updated { font-size: var(--text-xs); color: var(--color-text-muted); }

/* ============================================================
   PROGRESS BAR (reading progress)
   ============================================================ */
.reading-progress {
  position: fixed;
  top: var(--header-height);
  left: 0; right: 0;
  height: 3px;
  background: var(--color-border);
  z-index: 99;
}
.reading-progress__bar {
  height: 100%;
  background: linear-gradient(90deg, var(--color-accent), #a855f7);
  width: 0%;
  transition: width .1s linear;
}

/* ============================================================
   RESPONSIVE BREAKPOINTS
   ============================================================ */

/* Large screens: show TOC */
@media (min-width: 1280px) {
  .content { padding-right: calc(220px + var(--sp-10) + var(--sp-8)); }
  .toc { display: block; }
}

/* Medium screens */
@media (max-width: 1023px) {
  .sidebar {
    transform: translateX(-100%);
  }
  .sidebar.open {
    transform: translateX(0);
    box-shadow: var(--shadow-lg);
  }
  .sidebar-overlay.open { display: block; }
  .main { margin-left: 0; }
  .hamburger { display: flex; }
  .header__search { display: none; }
}

@media (max-width: 767px) {
  :root { --header-height: 56px; }
  .content { padding: var(--sp-6) var(--sp-4) var(--sp-12); }
  .page-title { font-size: var(--text-3xl); }
  .hero { padding: var(--sp-8) var(--sp-4); }
  .card-grid { grid-template-columns: 1fr; }
  .page-nav { grid-template-columns: 1fr; }
  .version-badge { display: none; }
  .header { padding: 0 var(--sp-4); gap: var(--sp-3); }
}

@media (max-width: 480px) {
  .hero__title { font-size: 1.75rem; }
  .hero__subtitle { font-size: var(--text-base); }
  .hero__actions { flex-direction: column; align-items: center; }
  .hero__actions .btn { width: 100%; max-width: 300px; }
}

/* Prefers reduced motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: .01ms !important;
    transition-duration: .01ms !important;
  }
  .reading-progress__bar { transition: none; }
}

/* Print */
@media print {
  .header, .sidebar, .toc, .reading-progress, .hamburger, .search-modal { display: none !important; }
  .main { margin: 0; }
  .content { max-width: 100%; padding: 0; }
}