:root {
  --bg: #0f1117;
  --surface: #181b24;
  --border: #282c36;
  --text: #e4e4e7;
  --text-muted: #6b7280;
  --accent: #4ecdc4;
  --accent-2: #7c5cff;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Cascadia Code", monospace;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(15, 17, 23, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  height: 56px;
}

.topbar-inner {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  font-weight: 800;
  font-size: 1.1rem;
  color: var(--text);
  text-decoration: none;
}

.logo:hover { text-decoration: none; opacity: .85; }

.topnav {
  display: flex;
  gap: 1.25rem;
  align-items: center;
}

.topnav a {
  font-size: .85rem;
  color: var(--text-muted);
  text-decoration: none;
  transition: color .2s;
}

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

.lang-link {
  font-weight: 700;
  padding: .2rem .5rem;
  border: 1px solid var(--border);
  border-radius: 4px;
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 2rem 0;
  text-align: center;
  color: var(--text-muted);
  font-size: .85rem;
}

@media (max-width: 640px) {
  .topnav { gap: .75rem; font-size: .8rem; }
}