@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800;900&family=Fira+Code:wght@400;500;600&display=swap');

:root {
  color-scheme: light;
  --bg: #f4faff;
  --bg-radial-1: rgba(0, 167, 212, 0.12);
  --bg-radial-2: rgba(7, 91, 232, 0.08);
  --surface: rgba(255, 255, 255, 0.88);
  --surface-solid: #ffffff;
  --surface-soft: #f0f8fd;
  --surface-tinted: #e3f4fc;
  --sidebar: rgba(255, 255, 255, 0.82);
  --text: #1b314f;
  --text-strong: #001126;
  --muted: #455b77;
  --muted-2: #7e99b8;
  --line: #d0eef7;
  --line-strong: #a8e3f4;
  --accent: #008bb3;
  --accent-bright: #00a7d4;
  --accent-2: #075be8;
  --accent-3: #19c8f2;
  --accent-soft: #e5f7fd;
  --accent-line: #a8e3f4;
  --success: #0d8253;
  --warning: #b36b00;
  --danger: #d91420;
  --modal: #f20d19;
  --code-bg: #00142a;
  --code-text: #dff6ff;
  --code-line: #0e294b;
  --radius-sm: 10px;
  --radius: 16px;
  --radius-lg: 24px;
  --sidebar-width: 310px;
  --toc-width: 236px;
  --content-width: 920px;
  --shadow-sm: 0 4px 14px rgba(0, 17, 38, 0.04);
  --shadow: 0 16px 40px rgba(0, 17, 38, 0.07);
  --shadow-lg: 0 28px 75px rgba(0, 17, 38, 0.12);
}

[data-theme="dark"] {
  color-scheme: dark;
  --bg: #030814;
  --bg-radial-1: rgba(0, 167, 212, 0.18);
  --bg-radial-2: rgba(7, 91, 232, 0.14);
  --surface: rgba(8, 20, 39, 0.82);
  --surface-solid: #09172d;
  --surface-soft: #051022;
  --surface-tinted: #0a2344;
  --sidebar: rgba(6, 16, 33, 0.84);
  --text: #c9ddef;
  --text-strong: #f3faff;
  --muted: #7e99b8;
  --muted-2: #4a6789;
  --line: rgba(168, 227, 244, 0.18);
  --line-strong: rgba(168, 227, 244, 0.32);
  --accent: #19c8f2;
  --accent-bright: #3de0ff;
  --accent-2: #4d8aff;
  --accent-3: #00a7d4;
  --accent-soft: rgba(0, 167, 212, 0.16);
  --accent-line: rgba(25, 200, 242, 0.35);
  --success: #2dd48f;
  --warning: #f59e0b;
  --danger: #ff4d5a;
  --modal: #ff3344;
  --code-bg: #02060f;
  --code-text: #e1f7ff;
  --code-line: #102647;
  --shadow-sm: 0 6px 18px rgba(0, 0, 0, 0.45);
  --shadow: 0 20px 50px rgba(0, 0, 0, 0.65);
  --shadow-lg: 0 32px 85px rgba(0, 0, 0, 0.85);
}

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

html {
  font-family: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.65;
  color: var(--text);
  background-color: var(--bg);
  background-image: 
    radial-gradient(ellipse 900px 500px at 15% -10%, var(--bg-radial-1), transparent),
    radial-gradient(ellipse 700px 450px at 85% 20%, var(--bg-radial-2), transparent);
  background-attachment: fixed;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  padding: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.skip-link {
  position: absolute;
  top: -999px;
  left: 20px;
  background: var(--accent);
  color: #fff;
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  z-index: 1000;
  font-weight: 600;
  text-decoration: none;
}
.skip-link:focus {
  top: 16px;
}

.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--accent), var(--accent-3), var(--accent-2));
  width: 0%;
  z-index: 999;
  transition: width 0.1s ease-out;
}

/* Topbar */
.topbar {
  display: none;
  align-items: center;
  justify-content: space-between;
  padding: 12px 20px;
  background: var(--sidebar);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 90;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-strong);
}

.brand-mark {
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, var(--accent), var(--accent-3));
  display: flex;
  align-items: center;
  justify-content: center;
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(0, 167, 212, 0.35);
  flex-shrink: 0;
}

.brand-icon {
  width: 22px;
  height: 22px;
}

.brand-title {
  display: block;
  font-weight: 800;
  font-size: 1.05rem;
  letter-spacing: -0.02em;
  color: var(--text-strong);
  line-height: 1.2;
}

.brand-subtitle {
  display: block;
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--accent);
  line-height: 1.2;
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.menu-btn, .theme-toggle {
  background: var(--surface-solid);
  border: 1px solid var(--line);
  color: var(--text-strong);
  padding: 7px 14px;
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-weight: 600;
  font-size: 0.85rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: all 0.2s ease;
}

.menu-btn:hover, .theme-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* Layout */
.layout {
  display: flex;
  width: 100%;
  max-width: 1540px;
  margin: 0 auto;
  min-height: 100vh;
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
  padding: 28px 20px 24px;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  background: var(--sidebar);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border-right: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  gap: 18px;
  z-index: 80;
}

.sidebar .brand {
  margin-bottom: 6px;
}

.search-wrap {
  position: relative;
}

.search {
  width: 100%;
  padding: 10px 14px 10px 36px;
  background: var(--surface-solid);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  color: var(--text-strong);
  font-family: inherit;
  font-size: 0.88rem;
  outline: none;
  transition: all 0.2s ease;
  background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="%237e99b8" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="11" cy="11" r="8"></circle><line x1="21" y1="21" x2="16.65" y2="16.65"></line></svg>');
  background-repeat: no-repeat;
  background-position: 12px center;
}

.search:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.nav {
  display: flex;
  flex-direction: column;
  gap: 3px;
  flex-grow: 1;
}

.nav-link {
  display: flex;
  align-items: center;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  color: var(--text);
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 500;
  transition: all 0.15s ease;
}

.nav-link:hover {
  background: var(--surface-soft);
  color: var(--accent);
  transform: translateX(3px);
}

.nav-link.active {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 700;
  border-left: 3px solid var(--accent);
  padding-left: 9px;
}

.sidebar-actions {
  padding-top: 12px;
  border-top: 1px solid var(--line);
}

.sidebar-actions .theme-toggle {
  width: 100%;
  justify-content: center;
}

.sidebar-footer {
  font-size: 0.76rem;
  color: var(--muted);
  border-top: 1px solid var(--line);
  padding-top: 12px;
}

.sidebar-footer p {
  margin: 0 0 8px 0;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted-2);
}

.social-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 12px;
}

.social-links a {
  color: var(--muted);
  text-decoration: none;
  transition: color 0.15s ease;
}

.social-links a:hover {
  color: var(--accent);
}

/* Content Container */
.content {
  flex-grow: 1;
  min-width: 0;
  display: flex;
  justify-content: center;
  padding: 40px 32px 80px;
}

.page {
  width: 100%;
  max-width: var(--content-width);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  color: var(--text-strong);
  font-weight: 800;
  letter-spacing: -0.025em;
  line-height: 1.25;
  margin-top: 1.8em;
  margin-bottom: 0.6em;
  position: relative;
}

h1 {
  font-size: 2.35rem;
  margin-top: 0;
  margin-bottom: 0.8em;
  letter-spacing: -0.035em;
  background: linear-gradient(135deg, var(--text-strong) 40%, var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

h2 {
  font-size: 1.55rem;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--line);
  margin-top: 2.2em;
}

h3 {
  font-size: 1.22rem;
  margin-top: 1.6em;
}

p, ul, ol {
  font-size: 1rem;
  line-height: 1.72;
  margin-bottom: 1.2em;
}

li {
  margin-bottom: 0.4em;
}

a {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-thickness: 1.5px;
  text-underline-offset: 3px;
  transition: all 0.15s ease;
}

a:hover {
  color: var(--accent-bright);
}

.anchor {
  text-decoration: none;
  color: var(--muted-2);
  margin-right: 6px;
  font-weight: 400;
  opacity: 0.5;
  transition: opacity 0.15s ease;
}

.anchor:hover {
  opacity: 1;
  color: var(--accent);
}

code {
  font-family: 'Fira Code', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  font-size: 0.88em;
  background: var(--surface-soft);
  color: var(--accent);
  padding: 2px 6px;
  border-radius: 6px;
  border: 1px solid var(--line);
}

pre {
  position: relative;
  background: var(--code-bg);
  border: 1px solid var(--code-line);
  border-radius: var(--radius);
  padding: 18px 22px;
  overflow-x: auto;
  box-shadow: var(--shadow-sm);
  margin: 1.4em 0;
}

.copy-code {
  position: absolute;
  top: 10px;
  right: 10px;
  z-index: 2;
  padding: 5px 10px;
  border: 1px solid var(--code-line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.08);
  color: var(--code-text);
  font-size: 12px;
  font-weight: 700;
  cursor: pointer;
  backdrop-filter: blur(8px);
  transition: all 0.15s ease;
}

.copy-code:hover {
  background: rgba(255, 255, 255, 0.18);
  border-color: var(--accent-bright);
  color: #ffffff;
}

pre code {
  background: transparent;
  color: var(--code-text);
  padding: 0;
  border: none;
  font-size: 0.9em;
  line-height: 1.6;
}

/* Callouts / Alerts */
blockquote {
  margin: 1.5em 0;
  padding: 16px 20px;
  background: var(--surface-soft);
  border-left: 4px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  box-shadow: var(--shadow-sm);
}

blockquote p:last-child {
  margin-bottom: 0;
}

.alert-modal {
  background: rgba(242, 13, 25, 0.08);
  border-left: 4px solid var(--modal);
}

/* Tables */
.table-wrap {
  width: 100%;
  overflow-x: auto;
  margin: 1.5em 0;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-sm);
}

table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.94rem;
  background: var(--surface-solid);
}

th {
  background: var(--surface-soft);
  color: var(--text-strong);
  font-weight: 700;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
}

td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

tr:last-child td {
  border-bottom: none;
}

/* Media Figures */
.media-figure {
  margin: 2em 0;
  background: var(--surface-solid);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.media-figure:hover {
  box-shadow: var(--shadow-lg);
}

.media-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px;
  background: var(--surface-soft);
  border-bottom: 1px solid var(--line);
  font-size: 0.82rem;
  font-weight: 600;
}

.media-kind {
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.media-open {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.78rem;
}
.media-open:hover {
  color: var(--accent);
}

.media-link {
  display: block;
  background: var(--surface-soft);
}

.media-link img {
  display: block;
  width: 100%;
  height: auto;
  max-height: 580px;
  object-fit: contain;
}

figcaption {
  padding: 12px 18px;
  font-size: 0.88rem;
  color: var(--muted);
  background: var(--surface-solid);
  border-top: 1px solid var(--line);
}

/* Cards Grid */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
  gap: 18px;
  margin: 1.8em 0;
}

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--shadow-sm);
  transition: all 0.2s ease;
  text-decoration: none;
  color: var(--text);
  display: flex;
  flex-direction: column;
}

.card:hover {
  border-color: var(--accent);
  transform: translateY(-3px);
  box-shadow: var(--shadow);
}

.card-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background: var(--accent-soft);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  margin-bottom: 14px;
}

.card-title {
  font-size: 1.12rem;
  font-weight: 700;
  color: var(--text-strong);
  margin: 0 0 8px 0;
}

.card-text {
  font-size: 0.9rem;
  color: var(--muted);
  margin: 0;
  line-height: 1.55;
}

/* Page Navigation & Footer */
.page-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 3.5em;
  padding-top: 1.8em;
  border-top: 1px solid var(--line);
}

.page-nav a {
  display: flex;
  flex-direction: column;
  padding: 14px 20px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  text-decoration: none;
  box-shadow: var(--shadow-sm);
  transition: all 0.2s ease;
  min-width: 200px;
}

.page-nav a:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.page-nav .next {
  margin-left: auto;
  text-align: right;
}

.page-nav .label {
  font-size: 0.74rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
  font-weight: 600;
}

.page-nav .title {
  font-size: 0.98rem;
  font-weight: 700;
  color: var(--accent);
}

.page-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 3em;
  padding-top: 1.5em;
  border-top: 1px solid var(--line);
  font-size: 0.82rem;
  color: var(--muted);
}

/* TOC (Table of contents) */
.toc {
  width: var(--toc-width);
  flex-shrink: 0;
  padding: 40px 0 24px 28px;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  font-size: 0.84rem;
}

.toc-title {
  font-size: 0.74rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted-2);
  margin-bottom: 12px;
}

.toc nav {
  display: flex;
  flex-direction: column;
  gap: 6px;
  border-left: 1px solid var(--line);
}

.toc nav a {
  color: var(--muted);
  text-decoration: none;
  padding-left: 12px;
  border-left: 2px solid transparent;
  margin-left: -1px;
  transition: all 0.15s ease;
  line-height: 1.45;
}

.toc nav a:hover {
  color: var(--accent);
  border-left-color: var(--accent-line);
}

.toc nav a.active {
  color: var(--accent);
  font-weight: 700;
  border-left-color: var(--accent);
}

.toc-h3 {
  padding-left: 20px !important;
  font-size: 0.8rem;
}

.mobile-scrim {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 17, 38, 0.5);
  backdrop-filter: blur(4px);
  z-index: 75;
}

/* Responsive */
@media (max-width: 1280px) {
  .toc {
    display: none;
  }
}

@media (max-width: 960px) {
  .topbar {
    display: flex;
  }

  .sidebar {
    position: fixed;
    top: 0;
    left: -320px;
    height: 100vh;
    transition: left 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: var(--shadow-lg);
  }

  .sidebar.open {
    left: 0;
  }

  .mobile-scrim.open {
    display: block;
  }

  .content {
    padding: 24px 20px 60px;
  }

  h1 {
    font-size: 1.85rem;
  }

  .page-nav {
    flex-direction: column;
  }
  .page-nav a {
    width: 100%;
    text-align: left;
  }
  .page-nav .next {
    text-align: left;
  }
}