:root {
  --bg: #ffffff;
  --bg-soft: #f8f9fa;
  --text: #1f2933;
  --text-secondary: #6b7280;
  --accent: #2563eb;
  --accent-soft: rgba(37, 99, 235, 0.08);
  --border: #e5e7eb;
  --radius: 10px;
  --max-width: 720px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial,
    sans-serif;
  --font-mono: "SF Mono", "JetBrains Mono", "Fira Code", Menlo, Consolas,
    monospace;
}

[data-theme="dark"] {
  --bg: #111827;
  --bg-soft: #1f2937;
  --text: #f3f4f6;
  --text-secondary: #9ca3af;
  --accent: #60a5fa;
  --accent-soft: rgba(96, 165, 250, 0.12);
  --border: #374151;
}

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

html {
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  transition: background-color 0.3s ease;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.logo {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
  letter-spacing: 0.02em;
}

.logo:hover {
  color: var(--accent);
}

.site-nav {
  display: flex;
  gap: 28px;
}

.nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  padding: 4px 0;
  border-bottom: 2px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease;
}

.nav-link:hover,
.nav-link.active {
  color: var(--text);
  border-bottom-color: var(--accent);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.25s ease, opacity 0.25s ease;
}

.nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ---------- Main ---------- */
.main {
  min-height: calc(100vh - 60px - 70px);
  padding-top: 64px;
  padding-bottom: 80px;
}

/* Intro */
.intro {
  margin-bottom: 56px;
}

.intro-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.intro-desc {
  color: var(--text-secondary);
  font-size: 1.05rem;
}

/* Section */
.section-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 24px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

/* Post cards */
.posts {
  display: flex;
  flex-direction: column;
  gap: 36px;
}

.post-card {
  padding: 4px 0;
}

.post-title {
  font-size: 1.3rem;
  font-weight: 600;
  margin-bottom: 6px;
}

.post-title a {
  color: var(--text);
  text-decoration: none;
  transition: color 0.2s ease;
}

.post-title a:hover {
  color: var(--accent);
}

.post-meta {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 10px;
}

.post-excerpt {
  color: var(--text-secondary);
  font-size: 0.98rem;
}

/* ---------- Prose (article / about) ---------- */
.prose h1 {
  font-size: 1.9rem;
  font-weight: 700;
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}

.prose h2 {
  font-size: 1.35rem;
  font-weight: 600;
  margin-top: 36px;
  margin-bottom: 14px;
}

.prose h3 {
  font-size: 1.15rem;
  font-weight: 600;
  margin-top: 28px;
  margin-bottom: 12px;
}

.prose p {
  margin-bottom: 18px;
  color: var(--text);
}

.prose a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s ease;
}

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

.prose ul,
.prose ol {
  margin: 0 0 18px 1.5em;
}

.prose li {
  margin-bottom: 8px;
}

.prose blockquote {
  margin: 24px 0;
  padding: 4px 0 4px 20px;
  border-left: 3px solid var(--accent);
  color: var(--text-secondary);
  font-style: italic;
}

.prose code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--accent-soft);
  color: var(--accent);
  padding: 2px 6px;
  border-radius: 4px;
}

.prose pre {
  font-family: var(--font-mono);
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  overflow-x: auto;
  margin-bottom: 18px;
  font-size: 0.9rem;
}

.prose pre code {
  background: none;
  color: var(--text);
  padding: 0;
}

.post-header {
  margin-bottom: 32px;
}

.post-header h1 {
  margin-bottom: 12px;
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 20px 0;
}

.footer-inner p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  text-align: center;
}

/* ---------- Responsive ---------- */
@media (max-width: 640px) {
  .nav-toggle {
    display: flex;
  }

  .site-nav {
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
  }

  .site-nav.open {
    max-height: 300px;
  }

  .nav-link {
    padding: 14px 20px;
    border-bottom: 1px solid var(--border);
    border-bottom-color: transparent;
  }

  .nav-link:hover,
  .nav-link.active {
    border-bottom-color: transparent;
    background: var(--bg-soft);
  }

  .intro-title {
    font-size: 1.6rem;
  }
}