:root {
  --background: 0 0% 100%;
  --foreground: 222.2 84% 4.9%;

  --card: 0 0% 100%;
  --card-foreground: 222.2 84% 4.9%;

  --popover: 0 0% 100%;
  --popover-foreground: 222.2 84% 4.9%;

  --primary: 210 90% 42%;
  --primary-foreground: 0 0% 100%;

  --secondary: 210 40% 96.1%;
  --secondary-foreground: 222.2 47.4% 11.2%;

  --muted: 210 40% 96.1%;
  --muted-foreground: 215.4 16.3% 46.9%;

  --accent: 210 100% 97%;
  --accent-foreground: 210 90% 35%;

  --destructive: 0 84.2% 60.2%;
  --destructive-foreground: 210 40% 98%;

  --border: 214.3 31.8% 89%;
  --input: 214.3 31.8% 89%;
  --ring: 210 90% 42%;

  --radius: 0.75rem;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.12);
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: 222.2 84% 4.9%;
    --foreground: 210 40% 98%;

    --card: 222.2 84% 4.9%;
    --card-foreground: 210 40% 98%;

    --popover: 222.2 84% 4.9%;
    --popover-foreground: 210 40% 98%;

    --primary: 210 90% 56%;
    --primary-foreground: 0 0% 100%;

    --secondary: 217.2 32.6% 17.5%;
    --secondary-foreground: 210 40% 98%;

    --muted: 217.2 32.6% 17.5%;
    --muted-foreground: 215 20.2% 65.1%;

    --accent: 210 70% 18%;
    --accent-foreground: 210 40% 98%;

    --destructive: 0 62.8% 30.6%;
    --destructive-foreground: 210 40% 98%;

    --border: 217.2 28% 22%;
    --input: 217.2 28% 22%;
    --ring: 210 90% 56%;
  }
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color: hsl(var(--foreground));
  background: hsl(var(--background));
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 16px;
  border-bottom: 1px solid hsl(var(--border));
  background: hsl(var(--background) / 0.85);
  backdrop-filter: blur(10px);
}

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

.logo {
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: hsl(var(--primary));
  color: hsl(var(--primary-foreground));
  display: grid;
  place-items: center;
  font-weight: 800;
  box-shadow: var(--shadow);
}

.title {
  font-weight: 700;
  letter-spacing: -0.01em;
}

.search {
  flex: 1;
  display: flex;
  justify-content: flex-end;
}

.search input {
  width: min(520px, 100%);
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid hsl(var(--input));
  background: hsl(var(--background));
  color: hsl(var(--foreground));
  outline: none;
}

.search input::placeholder {
  color: hsl(var(--muted-foreground));
}

.layout {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 14px;
  padding: 14px;
}

.sidebar {
  position: sticky;
  top: 72px;
  align-self: start;
  border: 1px solid hsl(var(--border));
  border-radius: 16px;
  padding: 14px;
  background: hsl(var(--card));
  box-shadow: var(--shadow);
}

.sidebarTitle {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: hsl(var(--muted-foreground));
  margin-bottom: 10px;
}

.toc {
  display: flex;
  flex-direction: column;
  gap: 6px;
  max-height: calc(100vh - 160px);
  overflow: auto;
  padding-right: 4px;
}

.tocItem {
  color: hsl(var(--muted-foreground));
  text-decoration: none;
  border-radius: 10px;
  padding: 8px 10px;
  border: 1px solid transparent;
}

.tocItem:hover {
  border-color: hsl(var(--border));
  background: hsl(var(--accent));
  color: hsl(var(--accent-foreground));
}

.tocItem.lvl1 {
  font-weight: 700;
  color: hsl(var(--foreground));
}

.tocItem.lvl2 {
  padding-left: 12px;
}

.tocItem.lvl3 {
  padding-left: 22px;
  font-size: 13px;
}

.sidebarHint {
  margin-top: 12px;
  font-size: 12px;
  color: hsl(var(--muted-foreground));
}

.content {
  border: 1px solid hsl(var(--border));
  border-radius: 16px;
  background: hsl(var(--card));
  box-shadow: var(--shadow);
  padding: 16px;
  min-height: 60vh;
}

.status {
  padding: 12px;
  border: 1px solid hsl(var(--border));
  border-radius: 12px;
  color: hsl(var(--muted-foreground));
  background: hsl(var(--secondary));
}

.status.error {
  border-color: rgba(239, 68, 68, 0.35);
  background: rgba(239, 68, 68, 0.12);
  color: rgba(255, 255, 255, 0.9);
}

.article {
  color: hsl(var(--foreground));
  line-height: 1.6;
}

.article h1,
.article h2,
.article h3 {
  letter-spacing: -0.01em;
}

.article h1 {
  margin-top: 6px;
  font-size: 28px;
}

.article h2 {
  margin-top: 26px;
  padding-top: 10px;
  border-top: 1px solid hsl(var(--border));
  font-size: 20px;
}

.article h3 {
  margin-top: 18px;
  font-size: 16px;
}

.article a {
  color: hsl(var(--primary));
}

.article code {
  background: hsl(var(--muted));
  border: 1px solid hsl(var(--border));
  border-radius: 8px;
  padding: 2px 6px;
}

.article pre {
  background: hsl(var(--muted));
  border: 1px solid hsl(var(--border));
  border-radius: 14px;
  padding: 14px;
  overflow: auto;
}

.section {
  margin-top: 8px;
}

.muted {
  color: hsl(var(--muted-foreground));
}

@media (max-width: 900px) {
  .layout {
    grid-template-columns: 1fr;
  }
  .sidebar {
    position: static;
  }
}