/* ===== Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #ffffff;
  --fg: #1a1a1a;
  --muted: #6b7280;
  --border: #e5e7eb;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --tag-bg: #f3f4f6;
  --code-bg: #f8fafc;
  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", "Courier New", monospace;
  --max-width: 720px;
  --radius: 6px;
}

html { font-size: 16px; scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--fg);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; transition: color .15s; }
a:hover { color: var(--accent-hover); text-decoration: underline; }

/* ===== Layout ===== */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

main.container { padding-top: 2.5rem; padding-bottom: 4rem; }

/* ===== Header ===== */
.site-header {
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(8px);
  z-index: 100;
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--fg);
  letter-spacing: -.02em;
}
.site-title:hover { text-decoration: none; color: var(--accent); }

.site-nav { display: flex; gap: 1.5rem; }
.site-nav a {
  font-size: .9rem;
  color: var(--muted);
  font-weight: 500;
  transition: color .15s;
}
.site-nav a:hover, .site-nav a.active { color: var(--accent); text-decoration: none; }

/* ===== Footer ===== */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 0;
  margin-top: 4rem;
}
.site-footer p { font-size: .85rem; color: var(--muted); text-align: center; }
.site-footer a { color: var(--muted); }
.site-footer a:hover { color: var(--accent); }

/* ===== Home ===== */
.hero {
  padding: 3rem 0 2.5rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2.5rem;
}
.hero h1 { font-size: 2rem; font-weight: 800; letter-spacing: -.03em; margin-bottom: .5rem; }
.hero .tagline { color: var(--muted); font-size: 1.05rem; }

.section-title {
  font-size: 1rem;
  font-weight: 600;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: .08em;
  margin-bottom: 1.5rem;
}

/* ===== Post List ===== */
.post-item {
  padding: 1.4rem 0;
  border-bottom: 1px solid var(--border);
}
.post-item:last-child { border-bottom: none; }

.post-meta {
  font-size: .82rem;
  color: var(--muted);
  margin-bottom: .4rem;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: .4rem;
}

.post-title { font-size: 1.15rem; font-weight: 600; margin-bottom: .4rem; }
.post-title a { color: var(--fg); }
.post-title a:hover { color: var(--accent); text-decoration: none; }

.post-summary { font-size: .92rem; color: var(--muted); line-height: 1.65; }

.tag {
  display: inline-block;
  padding: .1rem .5rem;
  background: var(--tag-bg);
  border-radius: 99px;
  font-size: .75rem;
  color: var(--muted);
}

.empty-tip { color: var(--muted); font-size: .95rem; padding: 2rem 0; }

/* ===== Post List Page ===== */
.post-list-page { padding-top: .5rem; }
.page-title {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 2px solid var(--fg);
  letter-spacing: -.02em;
}

/* ===== Single Post ===== */
.single-post { max-width: 100%; }

.post-header {
  padding: 2rem 0 1.8rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2rem;
}
.post-header .post-title { font-size: 1.8rem; font-weight: 800; letter-spacing: -.03em; margin-bottom: .75rem; }
.post-header .post-meta a { color: var(--muted); }
.post-header .post-meta a:hover { color: var(--accent); }

/* ===== Post Content ===== */
.post-content { font-size: 1rem; line-height: 1.85; }

.post-content h1,.post-content h2,.post-content h3,
.post-content h4,.post-content h5,.post-content h6 {
  font-weight: 700;
  letter-spacing: -.02em;
  margin: 2rem 0 .75rem;
  line-height: 1.35;
}
.post-content h1 { font-size: 1.6rem; }
.post-content h2 { font-size: 1.35rem; padding-bottom: .4rem; border-bottom: 1px solid var(--border); }
.post-content h3 { font-size: 1.15rem; }

.post-content p { margin: 1rem 0; }
.post-content ul, .post-content ol { margin: 1rem 0; padding-left: 1.6rem; }
.post-content li { margin: .4rem 0; }
.post-content blockquote {
  border-left: 3px solid var(--accent);
  margin: 1.5rem 0;
  padding: .75rem 1.2rem;
  background: var(--tag-bg);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: var(--muted);
  font-style: italic;
}
.post-content code {
  font-family: var(--font-mono);
  font-size: .88em;
  background: var(--code-bg);
  padding: .15em .35em;
  border-radius: 3px;
  border: 1px solid var(--border);
}
.post-content pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.2rem;
  overflow-x: auto;
  margin: 1.5rem 0;
  font-size: .88rem;
  line-height: 1.6;
}
.post-content pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: inherit;
}
.post-content img {
  max-width: 100%;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  display: block;
  margin: 1.5rem auto;
}
.post-content a { text-decoration: underline; text-underline-offset: 2px; }
.post-content hr { border: none; border-top: 1px solid var(--border); margin: 2rem 0; }
.post-content table { width: 100%; border-collapse: collapse; margin: 1.5rem 0; font-size: .92rem; }
.post-content th, .post-content td { border: 1px solid var(--border); padding: .5rem .75rem; text-align: left; }
.post-content th { background: var(--tag-bg); font-weight: 600; }

.post-footer { margin-top: 3rem; padding-top: 1.5rem; border-top: 1px solid var(--border); }
.back-link { font-size: .9rem; color: var(--muted); }
.back-link:hover { color: var(--accent); }

/* ===== About ===== */
.about-page { padding-top: .5rem; }
.about-page .page-title { font-size: 1.6rem; font-weight: 700; margin-bottom: 2rem; }
.about-content { font-size: 1rem; line-height: 1.85; }

/* ===== Responsive ===== */
@media (max-width: 600px) {
  .hero h1 { font-size: 1.6rem; }
  .post-header .post-title { font-size: 1.4rem; }
  .site-nav { gap: 1rem; }
}