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

:root {
  --bg: #f5f8fa;
  --text-primary: #1a3347;
  --text-body: #3d5466;
  --text-muted: #5a7b8f;
  --text-faint: #7a96a8;
  --text-footer: #8fa8b8;
  --accent: #2d5f7a;
  --accent-light: #9dc0db;
  --accent-hover: #1a4a62;
  --nav-bg: rgba(255, 255, 255, 0.92);
  --nav-border: rgba(45, 95, 122, 0.08);
  --nav-hover-bg: rgba(157, 192, 219, 0.15);
  --nav-active-bg: rgba(157, 192, 219, 0.18);
  --border: rgba(45, 95, 122, 0.1);
  --link-underline: rgba(45, 95, 122, 0.25);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #101418;
    --text-primary: #e2e8ee;
    --text-body: #959ea8;
    --text-muted: #6b7680;
    --text-faint: #525c65;
    --text-footer: #454e56;
    --accent: #7bb8d6;
    --accent-light: #3d7a99;
    --accent-hover: #a0d0e8;
    --nav-bg: rgba(20, 24, 30, 0.88);
    --nav-border: rgba(255, 255, 255, 0.06);
    --nav-hover-bg: rgba(255, 255, 255, 0.06);
    --nav-active-bg: rgba(255, 255, 255, 0.08);
    --border: rgba(255, 255, 255, 0.07);
    --link-underline: rgba(123, 184, 214, 0.3);
  }
}

body {
  font-family: Inter, -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text-primary);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Nav */
.nav {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 3rem;
  height: 56px;
  background: var(--nav-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--nav-border);
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  text-decoration: none;
  color: var(--text-primary);
}

.nav-brand img {
  width: 28px;
  height: 28px;
  border-radius: 7px;
}

.nav-brand span {
  font-weight: 600;
  font-size: 0.875rem;
  letter-spacing: -0.01em;
}

.nav-links {
  display: flex;
  gap: 0.25rem;
}

.nav-links a {
  color: var(--text-muted);
  font-size: 0.8125rem;
  font-weight: 500;
  text-decoration: none;
  padding: 0.375rem 0.875rem;
  border-radius: 6px;
  transition: background 0.15s, color 0.15s;
}

.nav-links a:hover {
  background: var(--nav-hover-bg);
  color: var(--accent);
}

.nav-links a.active {
  background: var(--nav-active-bg);
  color: var(--accent);
  font-weight: 600;
}

/* Hero */
.hero {
  padding: 4rem 3rem 0;
  max-width: 760px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.03em;
  line-height: 1.25;
}

.hero .meta {
  font-size: 0.8125rem;
  color: var(--text-faint);
  margin-top: 0.5rem;
}

.divider {
  max-width: 760px;
  margin: 2rem auto 0;
  border: none;
  border-top: 1px solid var(--border);
}

/* Content */
.content {
  max-width: 760px;
  margin: 0 auto;
  padding: 2.5rem 3rem 5rem;
}

.content p {
  font-size: 0.9375rem;
  line-height: 1.85;
  color: var(--text-body);
  margin-bottom: 1.25rem;
}

.content h2 {
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-top: 2.75rem;
  margin-bottom: 0.75rem;
  padding-left: 0.75rem;
  border-left: 3px solid var(--accent-light);
  letter-spacing: -0.01em;
}

.content h2:first-child {
  margin-top: 0;
}

.content ul {
  margin: 0.75rem 0 1.5rem 1.25rem;
  font-size: 0.9375rem;
  line-height: 1.85;
  color: var(--text-body);
}

.content ul li {
  margin-bottom: 0.5rem;
  padding-left: 0.375rem;
}

.content ul li::marker {
  color: var(--accent-light);
}

.content strong {
  color: var(--text-primary);
  font-weight: 600;
}

.content a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid var(--link-underline);
  transition: border-color 0.2s, color 0.2s;
}

.content a:hover {
  color: var(--accent-hover);
  border-color: var(--accent);
}

/* Footer */
.page-footer {
  max-width: 760px;
  margin: 0 auto;
  padding: 1.5rem 3rem 3rem;
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.page-footer span {
  color: var(--text-footer);
  font-size: 0.8125rem;
}

.page-footer a {
  color: var(--text-muted);
  font-size: 0.8125rem;
  text-decoration: none;
  transition: color 0.15s;
}

.page-footer a:hover {
  color: var(--accent);
}

@media (max-width: 640px) {
  .nav { padding: 0 1.25rem; }
  .hero { padding: 3rem 1.5rem 0; }
  .hero h1 { font-size: 1.625rem; }
  .content { padding: 2rem 1.5rem 3rem; }
  .divider { margin-left: 1.5rem; margin-right: 1.5rem; }
  .page-footer { padding: 1.5rem; flex-direction: column; gap: 0.75rem; }
}