* {
  box-sizing: border-box;
}

:root {
  color-scheme: dark;
  --bg: #0b1220;
  --bg-accent: #0f1a30;
  --panel: #111827;
  --panel-2: #0f172a;
  --border: #243041;
  --border-soft: rgba(255, 255, 255, 0.05);
  --text: #e5e7eb;
  --muted: #94a3b8;
  --link: #7dd3fc;
  --link-hover: #bae6fd;
  --heading: #f8fafc;
  --accent: #38bdf8;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
}

html,
body {
  margin: 0;
  padding: 0;
  min-height: 100%;
  background:
    radial-gradient(circle at top left, rgba(56, 189, 248, 0.06), transparent 24%),
    linear-gradient(180deg, var(--bg-accent) 0%, var(--bg) 100%);
  color: var(--text);
  font-family: Arial, Helvetica, sans-serif;
}

body {
  height: 100vh;
  overflow: hidden;
}

a {
  color: var(--link);
  text-decoration: none;
}

a:hover {
  color: var(--link-hover);
  text-decoration: underline;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  height: 72px;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(
  180deg,
  rgba(11, 18, 32, 0.98),
  rgba(11, 18, 32, 0.85)
  );
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
}

.brand a {
  color: var(--heading);
  font-size: 1.55rem;
  font-weight: 700;
  letter-spacing: 0.2px;
}

.topnav {
  display: flex;
  align-items: center;
  gap: 28px;
}

.topnav a {
  color: var(--muted);
  font-weight: 600;
  font-size: 0.98rem;
  transition: color 0.15s ease;
}

.topnav a:hover {
  color: var(--heading);
  text-decoration: none;
}

.page-shell {
  display: flex;
  height: calc(100vh - 72px);
}

.sidebar {
  width: 300px;
  flex-shrink: 0;
  border-right: 1px solid var(--border);
  background: rgba(15, 23, 42, 0.88);
  padding: 18px 14px 28px;
  overflow-y: auto;
}

.sidebar-module {
  margin-bottom: 10px;
}

.sidebar-module summary {
  list-style: none;
  cursor: pointer;
  color: var(--heading);
  font-size: 0.86rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
  padding: 10px 12px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  gap: 10px;
  transition: background 0.15s ease, color 0.15s ease;
}

.sidebar-module summary:hover {
  background: rgba(255, 255, 255, 0.04);
}

.sidebar-module summary::-webkit-details-marker {
  display: none;
}

.sidebar-module summary::before {
  content: "▸";
  color: var(--muted);
  font-size: 0.8rem;
  width: 10px;
  flex-shrink: 0;
  transition: transform 0.15s ease;
}

.sidebar-module[open] summary::before {
  transform: rotate(90deg);
}

.sidebar-module ul {
  list-style: none;
  padding: 4px 0 0 22px;
  margin: 0;
}

.sidebar li {
  margin: 0 0 4px;
}

.sidebar a {
  display: block;
  padding: 8px 10px;
  border-radius: 8px;
  color: var(--muted);
  transition:
    background 0.15s ease,
    color 0.15s ease,
    border-color 0.15s ease,
    transform 0.15s ease;
  line-height: 1.35;
  font-size: 0.98rem;
  border: 1px solid transparent;
}

.sidebar a:hover {
  background: rgba(56, 189, 248, 0.08);
  color: var(--heading);
  text-decoration: none;
  transform: translateX(2px);
}

.sidebar a.active {
  background: linear-gradient(
    90deg,
    rgba(56, 189, 248, 0.18),
    rgba(56, 189, 248, 0.08)
  );
  color: white;
  border: 1px solid rgba(56, 189, 248, 0.35);
  font-weight: 600;
  box-shadow: 0 0 0 1px rgba(56, 189, 248, 0.15);
}

.content {
  flex: 1;
  padding: 64px 64px 80px;
  overflow-y: auto;
}

.content-inner {
  max-width: 900px;
  background: rgba(17, 24, 39, 0.9);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 34px 40px 44px;
  box-shadow: var(--shadow);
}

.breadcrumbs {
  margin-bottom: 14px;
  font-size: 0.95rem;
  color: var(--muted);
  line-height: 1.4;
}

.breadcrumbs a {
  color: var(--link);
}

.breadcrumbs a:hover {
  color: var(--link-hover);
  text-decoration: none;
}

.breadcrumbs span {
  margin: 0 6px;
  color: var(--muted);
}

.content h1 {
  margin-top: 0;
  margin-bottom: 26px;
  color: var(--heading);
  font-size: 2.25rem;
  line-height: 1.12;
}

.content h2,
.content h3 {
  color: var(--heading);
}

.content h2 {
  margin-top: 36px;
  margin-bottom: 14px;
  font-size: 1.5rem;
}

.content h3 {
  margin-top: 28px;
  margin-bottom: 10px;
  font-size: 1.15rem;
}

.content p,
.content li {
  color: var(--text);
  font-size: 1.03rem;
  line-height: 1.75;
}

.content p {
  margin-bottom: 18px;
}

.content ul,
.content ol {
  padding-left: 22px;
}

.content strong {
  color: var(--heading);
}

.content code {
  background: #0f172a;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 2px 6px;
  font-size: 0.95em;
}

@media (max-width: 960px) {
  body {
    height: auto;
    overflow: auto;
  }

  .page-shell {
    flex-direction: column;
    height: auto;
  }

  .sidebar {
    width: 100%;
    border-right: none;
    border-bottom: 1px solid var(--border);
    max-height: none;
    overflow: visible;
  }

  .content {
    padding: 24px 16px 40px;
    overflow: visible;
  }

  .content-inner {
    max-width: 100%;
    padding: 24px;
  }

  .topbar {
    height: auto;
    padding: 16px 20px;
    align-items: flex-start;
    flex-direction: column;
    gap: 12px;
  }

  .topnav {
    gap: 18px;
    flex-wrap: wrap;
  }

  .content h1 {
    font-size: 1.9rem;
  }
}