:root {
  /* Default Dark Theme: Obsidian Night + Celestial Gold + Cosmic Violet */
  --bg-primary: #0d0b12;
  --bg-secondary: #14111b;
  --bg-tertiary: #1b1624;
  --bg-card: #171320;
  --bg-card-hover: #211b2e;
  
  --border-color: #2b2338;
  --border-highlight: #46375a;
  
  --text-primary: #f7f4fb;
  --text-secondary: #d0c7dc;
  --text-muted: #9b90ab;
  
  --accent-gold: #e5a93c;
  --accent-gold-hover: #f3be58;
  --accent-gold-bg: rgba(229, 169, 60, 0.08);
  --accent-gold-border: rgba(229, 169, 60, 0.25);
  
  --accent-purple: #c084fc;
  --accent-purple-bg: rgba(192, 132, 252, 0.08);
  --accent-purple-border: rgba(192, 132, 252, 0.25);
  
  --accent-crimson: #e05666;
  --accent-emerald: #34d399;
  --accent-cyan: #38bdf8;
  --accent-amber: #fbbf24;

  --header-bg: rgba(13, 11, 18, 0.95);
  --code-box-bg: #09070c;
  --code-box-header: var(--bg-secondary);
  --code-box-text: #e2e8f0;
  --code-inline-bg: var(--bg-tertiary);
  --code-inline-color: #e2e8f0;
  --code-inline-border: var(--border-color);
  --kbd-bg: #211b2e;
  --kbd-color: #f8fafc;
  --kbd-border: rgba(255, 255, 255, 0.2);
  --kbd-border-bottom: rgba(255, 255, 255, 0.35);
  --table-hover: rgba(255, 255, 255, 0.015);
  --toast-bg: #211b2e;
  --toast-color: #f8fafc;
  --toast-border: var(--border-highlight);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  
  --font-sans: 'IBM Plex Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
  
  --sidebar-width: 250px;
  --header-height: 60px;
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
}

/* Light Theme: Pristine Ivory Slate + Imperial Amber + Royal Violet */
[data-theme="light"] {
  --bg-primary: #f7f6fa;
  --bg-secondary: #ffffff;
  --bg-tertiary: #ede8f5;
  --bg-card: #ffffff;
  --bg-card-hover: #f4effb;
  
  --border-color: #dfd7eb;
  --border-highlight: #bcaed4;
  
  --text-primary: #191326;
  --text-secondary: #534866;
  --text-muted: #796c90;
  
  --accent-gold: #965b00;
  --accent-gold-hover: #7b4900;
  --accent-gold-bg: rgba(150, 91, 0, 0.08);
  --accent-gold-border: rgba(150, 91, 0, 0.25);
  
  --accent-purple: #7026b9;
  --accent-purple-bg: rgba(112, 38, 185, 0.08);
  --accent-purple-border: rgba(112, 38, 185, 0.25);
  
  --accent-crimson: #be123c;
  --accent-emerald: #047857;
  --accent-cyan: #0284c7;
  --accent-amber: #b45309;

  --header-bg: rgba(247, 246, 250, 0.95);
  --code-box-bg: #191426;
  --code-box-header: #241d35;
  --code-box-text: #f3edf9;
  --code-inline-bg: #ede7f6;
  --code-inline-color: #6b21a8;
  --code-inline-border: #d7c9e8;
  --kbd-bg: #ede7f6;
  --kbd-color: #2b1f42;
  --kbd-border: #c9bade;
  --kbd-border-bottom: #b09dc9;
  --table-hover: rgba(112, 38, 185, 0.035);
  --toast-bg: #ffffff;
  --toast-color: #191326;
  --toast-border: #bcaed4;
  --shadow-sm: 0 1px 3px rgba(35, 15, 60, 0.06);
  --shadow-md: 0 4px 14px rgba(35, 15, 60, 0.08);
}

html {
  scroll-behavior: smooth;
}

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

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.6;
  font-size: 15px;
  -webkit-font-smoothing: antialiased;
}

/* Bilingual switcher */
body[data-lang="vi"] .lang-en { display: none !important; }
body[data-lang="en"] .lang-vi { display: none !important; }

/* Scrollbar */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--bg-primary); }
::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--border-highlight); }

/* Header */
header.top-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--header-bg);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border-color);
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 3rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--text-primary);
}

.brand-avatar {
  width: 34px;
  height: 34px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--accent-gold-border);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.4);
  object-fit: cover;
  display: block;
}

.brand-title {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.brand-badge {
  font-size: 0.8rem;
  background: var(--bg-tertiary);
  color: var(--accent-gold);
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
  border: 1px solid var(--border-color);
  font-family: var(--font-mono);
  font-weight: 600;
}

.header-search {
  flex: 0 1 540px;
  position: relative;
}

.search-input {
  width: 100%;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.45rem 2.2rem 0.45rem 0.85rem;
  border-radius: var(--radius-sm);
  font-size: 0.86rem;
  outline: none;
  transition: border-color 0.15s;
}

.search-input:focus {
  border-color: var(--accent-gold);
}

.search-shortcut {
  position: absolute;
  right: 8px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 0.8rem;
  background: var(--bg-tertiary);
  color: var(--text-muted);
  padding: 0.1rem 0.35rem;
  border-radius: 3px;
  border: 1px solid var(--border-color);
  font-family: var(--font-mono);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

.theme-btn {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-primary);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 0.38rem 0.75rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s ease;
}

.theme-btn:hover {
  background: var(--bg-tertiary);
  border-color: var(--border-highlight);
}

.theme-btn svg {
  flex-shrink: 0;
}

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

:root:not([data-theme="light"]) .theme-icon-sun {
  display: block;
}
:root:not([data-theme="light"]) .theme-icon-moon {
  display: none;
}

.lang-btn {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-primary);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 0.38rem 0.75rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s ease;
}

.lang-btn:hover {
  background: var(--bg-tertiary);
  border-color: var(--border-highlight);
}

.nav-link-btn {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.82rem;
  color: var(--text-secondary);
  text-decoration: none;
  padding: 0.38rem 0.75rem;
  border-radius: var(--radius-sm);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  transition: all 0.15s;
}

.nav-link-btn:hover {
  color: var(--text-primary);
  border-color: var(--border-highlight);
}

.menu-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  cursor: pointer;
  padding: 0.2rem;
}

/* Layout */
.layout-wrapper {
  display: flex;
  margin-top: var(--header-height);
  min-height: calc(100vh - var(--header-height));
}

/* Condensed Sidebar */
aside.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  position: fixed;
  top: var(--header-height);
  bottom: 0;
  left: 0;
  overflow-y: auto;
  padding: 1.5rem 0.85rem;
  z-index: 90;
}

.sidebar-group {
  margin-bottom: 1.35rem;
}

.sidebar-title {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  font-weight: 700;
  margin-bottom: 0.45rem;
  padding-left: 0.6rem;
}

.sidebar-nav {
  list-style: none;
}

.sidebar-nav li a {
  display: block;
  padding: 0.5rem 0.75rem;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  transition: all 0.15s ease;
}

.sidebar-nav li a:hover {
  color: var(--text-primary);
  background: var(--bg-tertiary);
}

.sidebar-nav li a.active {
  color: var(--accent-gold);
  background: var(--accent-gold-bg);
  border-left: 2px solid var(--accent-gold);
  font-weight: 600;
}

/* Fluid Main Content Area - Expands naturally across desktop */
main.content-area {
  margin-left: var(--sidebar-width);
  flex: 1;
  min-width: 0;
  padding: 2.75rem 4.5rem 5rem 4.5rem;
}

/* Constrain text reading measure for paragraphs without cramping cards and tables */
p, .section-lead, .callout p {
  max-width: 72ch;
}

/* Hero */
.hero-banner {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 2rem 2.25rem;
  margin-bottom: 2.75rem;
}

.hero-tag {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent-gold);
  background: var(--accent-gold-bg);
  border: 1px solid var(--accent-gold-border);
  padding: 0.2rem 0.55rem;
  border-radius: 3px;
  margin-bottom: 0.65rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.hero-title {
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.025em;
  line-height: 1.25;
  margin-bottom: 0.6rem;
  color: var(--text-primary);
}

.hero-desc {
  color: var(--text-secondary);
  font-size: 0.98rem;
  line-height: 1.6;
}

/* Sections */
section.doc-section {
  margin-bottom: 3.75rem;
  scroll-margin-top: calc(var(--header-height) + 1.2rem);
}

.section-header {
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.75rem;
  margin-bottom: 1.5rem;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.25;
  color: var(--text-primary);
}

.section-lead {
  color: var(--text-muted);
  margin-top: 0.35rem;
  font-size: 0.92rem;
}

.subsection-title {
  color: var(--text-primary);
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.preset-title {
  color: var(--text-primary);
  font-size: 0.95rem;
  font-weight: 700;
  margin: 1.25rem 0 0.4rem 0;
}

/* In-Page Skill Tabs */
.skill-tabs {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.skill-tab-btn {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius-sm);
  font-size: 0.86rem;
  cursor: pointer;
  transition: all 0.15s ease;
}

.skill-tab-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.skill-tab-btn.active {
  background: var(--bg-tertiary);
  border-color: var(--accent-gold);
  color: var(--accent-gold);
  font-weight: 600;
}

/* Cards & Grid - Expands to fill wider viewports */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.15rem;
  margin-top: 1rem;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.35rem;
  transition: border-color 0.15s ease;
}

.card:hover {
  border-color: var(--border-highlight);
}

.card-title {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 0.45rem;
  color: var(--text-primary);
}

.card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* Skill Card */
.skill-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.4rem;
  margin-bottom: 1.25rem;
  transition: border-color 0.15s;
}

.skill-card:hover {
  border-color: var(--border-highlight);
}

.skill-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.skill-name {
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: -0.015em;
  color: var(--text-primary);
}

.badge {
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.2rem 0.55rem;
  border-radius: 3px;
  background: var(--bg-tertiary);
  color: var(--accent-gold);
  border: 1px solid var(--border-color);
  font-family: var(--font-mono);
}

.skill-card p {
  font-size: 0.92rem;
  color: var(--text-secondary);
  margin-bottom: 0.85rem;
}

.skill-specs {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 0.75rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 0.75rem 1.1rem;
  border-radius: var(--radius-sm);
  font-size: 0.86rem;
}

.spec-title {
  color: var(--text-muted);
  font-size: 0.8rem;
  display: block;
  margin-bottom: 0.2rem;
}

.spec-data {
  font-weight: 600;
  color: var(--text-primary);
}

/* Callouts */
.callout {
  padding: 1.1rem 1.35rem;
  border-radius: var(--radius-sm);
  margin: 1.25rem 0;
  font-size: 0.92rem;
  line-height: 1.6;
  border: 1px solid var(--border-color);
  background: var(--bg-secondary);
}

.callout.warning { border-color: rgba(229, 169, 60, 0.35); }
.callout.tip { border-color: rgba(52, 211, 153, 0.35); }

.callout-title {
  font-weight: 700;
  font-size: 0.92rem;
  margin-bottom: 0.35rem;
  color: var(--text-primary);
}

/* Tables without cramped wrapper */
.table-wrapper {
  overflow-x: auto;
  margin: 1.25rem 0;
}

table.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
}

table.data-table th {
  background: var(--bg-tertiary);
  color: var(--text-muted);
  padding: 0.8rem 1.1rem;
  font-weight: 600;
  text-transform: uppercase;
  font-size: 0.8rem;
  letter-spacing: 0.05em;
  border-bottom: 1px solid var(--border-color);
  text-align: left;
}

table.data-table td {
  padding: 0.8rem 1.1rem;
  border-bottom: 1px solid var(--border-color);
  color: var(--text-primary);
  line-height: 1.5;
}

table.data-table tr:last-child td { border-bottom: none; }
table.data-table tr:hover td { background: var(--table-hover); }

code {
  font-family: var(--font-mono);
  font-size: 0.86em;
  background: var(--code-inline-bg);
  border: 1px solid var(--code-inline-border);
  padding: 0.15rem 0.4rem;
  border-radius: 3px;
  color: var(--code-inline-color);
}

kbd {
  font-family: var(--font-mono);
  background: var(--kbd-bg);
  border: 1px solid var(--kbd-border);
  border-bottom: 2px solid var(--kbd-border-bottom);
  padding: 0.15rem 0.45rem;
  border-radius: 3px;
  font-size: 0.82em;
  color: var(--kbd-color);
}

/* Code Snippets */
.code-box {
  background: var(--code-box-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  margin: 1.15rem 0;
  overflow: hidden;
}

.code-header {
  background: var(--code-box-header);
  padding: 0.55rem 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-color);
  font-size: 0.78rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.copy-btn {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.25rem 0.65rem;
  border-radius: 3px;
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.15s ease;
}

.copy-btn:hover {
  background: var(--border-highlight);
  color: var(--text-primary);
}

pre {
  padding: 1.1rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.55;
  color: var(--code-box-text);
}

/* Footer */
footer.doc-footer {
  margin-top: 4rem;
  padding-top: 1.75rem;
  border-top: 1px solid var(--border-color);
  color: var(--text-muted);
  font-size: 0.85rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem;
}

/* Toast */
#toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background: var(--toast-bg);
  border: 1px solid var(--toast-border);
  color: var(--toast-color);
  padding: 0.6rem 1.15rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.85rem;
  opacity: 0;
  transform: translateY(15px);
  transition: all 0.2s ease;
  pointer-events: none;
  z-index: 1000;
  box-shadow: var(--shadow-md);
}

#toast.show {
  opacity: 1;
  transform: translateY(0);
}

/* Responsive */
@media (max-width: 900px) {
  .menu-toggle { display: block; }
  aside.sidebar {
    transform: translateX(-100%);
    transition: transform 0.2s ease;
  }
  aside.sidebar.open { transform: translateX(0); }
  main.content-area {
    margin-left: 0;
    padding: 1.5rem 1.25rem 3rem 1.25rem;
  }
  header.top-header {
    padding: 0 1.25rem;
  }
  .header-search { flex: 0 1 180px; }
  .search-shortcut { display: none; }
}