:root {
  --bg-0: #0a0a14;
  --bg-1: #131325;
  --bg-2: #1a1a32;
  --border: rgba(168, 85, 247, 0.18);
  --border-strong: rgba(168, 85, 247, 0.35);
  --text-1: #f5f5fa;
  --text-2: #c7c7d8;
  --text-3: #8a8aa5;
  --accent: #a855f7;
  --accent-cyan: #22d3ee;
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", Roboto, sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: radial-gradient(circle at 20% 0%, #1a1240 0%, var(--bg-0) 60%) fixed;
  color: var(--text-1);
  font-family: var(--font);
  min-height: 100vh;
  line-height: 1.6;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.1rem 2rem;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: rgba(10, 10, 20, 0.85);
  backdrop-filter: blur(10px);
  z-index: 10;
}
.brand { display: flex; align-items: baseline; gap: 0.5rem; text-decoration: none; color: inherit; }
.brand-mark {
  font-weight: 800;
  font-size: 1.35rem;
  background: linear-gradient(90deg, var(--accent), var(--accent-cyan));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  letter-spacing: 0.04em;
}
.brand-tool { font-size: 0.9rem; color: var(--text-3); }
nav a {
  color: var(--text-2);
  text-decoration: none;
  margin-left: 1.5rem;
  font-size: 0.9rem;
}
nav a:hover { color: var(--text-1); }

.layout {
  display: grid;
  grid-template-columns: 240px 1fr;
  max-width: 1280px;
  margin: 0 auto;
  min-height: calc(100vh - 130px);
}

.sidebar {
  border-right: 1px solid var(--border);
  padding: 2rem 1rem 2rem 2rem;
  position: sticky;
  top: 60px;
  height: calc(100vh - 60px);
  overflow-y: auto;
}
.sidebar ul { list-style: none; padding: 0; margin: 0; }
.sidebar li { margin: 0.15rem 0; }
.sidebar li.sidebar-group {
  font-size: 0.7rem;
  color: var(--text-3);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin: 1.4rem 0 0.5rem 0;
}
.sidebar a {
  display: block;
  color: var(--text-2);
  text-decoration: none;
  padding: 0.4rem 0.75rem;
  border-radius: 6px;
  font-size: 0.92rem;
}
.sidebar a:hover { background: var(--bg-2); color: var(--text-1); }
.sidebar a.active { background: rgba(168, 85, 247, 0.15); color: var(--text-1); border-left: 3px solid var(--accent); padding-left: calc(0.75rem - 3px); }

.content {
  padding: 2.5rem 3rem 4rem;
  max-width: 880px;
}
.content .loading { color: var(--text-3); font-style: italic; }

.content h1 {
  font-size: 2.1rem;
  margin: 0 0 0.5rem 0;
  background: linear-gradient(90deg, var(--accent), var(--accent-cyan));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.content h2 {
  margin-top: 2.5rem;
  margin-bottom: 0.75rem;
  font-size: 1.4rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--border);
}
.content h3 { margin-top: 1.75rem; font-size: 1.1rem; color: var(--text-1); }
.content h4 { margin-top: 1.4rem; font-size: 0.95rem; color: var(--text-2); text-transform: uppercase; letter-spacing: 0.06em; }
.content p { color: var(--text-2); margin: 0.8rem 0; }
.content ul, .content ol { color: var(--text-2); padding-left: 1.5rem; margin: 0.75rem 0; }
.content li { margin: 0.3rem 0; }
.content a { color: var(--accent-cyan); text-decoration: none; }
.content a:hover { text-decoration: underline; }

.content code {
  font-family: var(--mono);
  background: var(--bg-2);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  font-size: 0.88em;
  color: var(--accent-cyan);
}
.content pre {
  background: var(--bg-0);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1rem 1.25rem;
  overflow-x: auto;
  margin: 1rem 0;
}
.content pre code {
  background: none;
  padding: 0;
  font-size: 0.85rem;
  color: var(--text-1);
}

.content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.25rem 0;
}
.content th, .content td {
  text-align: left;
  padding: 0.5rem 0.75rem;
  border-bottom: 1px solid var(--border);
  font-size: 0.92rem;
}
.content th { color: var(--text-3); text-transform: uppercase; letter-spacing: 0.05em; font-size: 0.8rem; font-weight: 600; }

.content blockquote {
  border-left: 3px solid var(--accent);
  padding: 0.5rem 1.25rem;
  margin: 1rem 0;
  background: var(--bg-1);
  border-radius: 0 8px 8px 0;
  color: var(--text-2);
}

footer {
  text-align: center;
  padding: 1.5rem 2rem;
  border-top: 1px solid var(--border);
  color: var(--text-3);
  font-size: 0.85rem;
}
footer a { color: var(--text-2); text-decoration: none; }
footer a:hover { color: var(--text-1); }
footer .sep { margin: 0 0.6rem; opacity: 0.5; }

@media (max-width: 820px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar { position: static; height: auto; border-right: none; border-bottom: 1px solid var(--border); padding: 1.25rem 2rem; }
  .content { padding: 2rem 1.5rem 3rem; }
}