/* === 设计令牌 === */
:root {
  --bg: #fafafa;
  --bg-card: #ffffff;
  --bg-hover: #f5f5f5;
  --text: #1a1a1a;
  --text-secondary: #666666;
  --text-muted: #999999;
  --border: #e5e5e5;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-light: #eff6ff;
  --tag-bg: #f0f0f0;
  --tag-text: #555;
  --hero-bg: linear-gradient(135deg, #f0f7ff 0%, #faf5ff 50%, #fff7ed 100%);
  --shadow: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-lg: 0 4px 24px rgba(0,0,0,0.08);
  --radius: 12px;
  --radius-sm: 8px;
  --max-width: 720px;
  --max-wide: 1100px;
}

[data-theme="dark"] {
  --bg: #0f0f0f;
  --bg-card: #1a1a1a;
  --bg-hover: #252525;
  --text: #f0f0f0;
  --text-secondary: #a0a0a0;
  --text-muted: #666;
  --border: #2a2a2a;
  --accent: #60a5fa;
  --accent-hover: #93bbfd;
  --accent-light: #1e293b;
  --tag-bg: #252525;
  --tag-text: #b0b0b0;
  --hero-bg: linear-gradient(135deg, #0f172a 0%, #1a1025 50%, #1a120b 100%);
  --shadow: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-lg: 0 4px 24px rgba(0,0,0,0.4);
}

/* === 基础重置 === */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,'Helvetica Neue',Arial,'Noto Sans SC',sans-serif;
  background:var(--bg);
  color:var(--text);
  line-height:1.7;
  transition:background .3s,color .3s;
  -webkit-font-smoothing:antialiased;
}
a{color:var(--accent);text-decoration:none;transition:color .2s}
a:hover{color:var(--accent-hover)}
img{max-width:100%;height:auto}
h1,h2,h3,h4{line-height:1.3;font-weight:700}
h1{font-size:2rem;margin-bottom:.5em}
h2{font-size:1.5rem;margin:1.5em 0 .5em}
h3{font-size:1.2rem;margin:1.2em 0 .4em}
p{margin-bottom:1em}
ul,ol{padding-left:1.5em;margin-bottom:1em}
li{margin-bottom:.3em}
blockquote{
  border-left:3px solid var(--accent);
  padding:.5em 1em;
  margin:1em 0;
  background:var(--accent-light);
  border-radius:0 var(--radius-sm) var(--radius-sm) 0;
  color:var(--text-secondary);
}
code{
  background:var(--tag-bg);
  padding:.15em .4em;
  border-radius:4px;
  font-size:.9em;
}
pre{
  background:var(--bg-card);
  border:1px solid var(--border);
  border-radius:var(--radius-sm);
  padding:1em;
  overflow-x:auto;
  margin:1em 0;
}
pre code{background:none;padding:0}

/* === 布局 === */
.container{max-width:var(--max-wide);margin:0 auto;padding:0 1.5rem}
.container-narrow{max-width:var(--max-width);margin:0 auto;padding:0 1.5rem}

/* === 导航 === */
.nav{
  position:sticky;top:0;z-index:100;
  background:rgba(250,250,250,.85);
  backdrop-filter:blur(12px);
  -webkit-backdrop-filter:blur(12px);
  border-bottom:1px solid var(--border);
  transition:background .3s;
}
[data-theme="dark"] .nav{background:rgba(15,15,15,.85)}
.nav-inner{
  max-width:var(--max-wide);
  margin:0 auto;
  padding:.75rem 1.5rem;
  display:flex;
  align-items:center;
  justify-content:space-between;
}
.nav-brand{
  font-weight:800;
  font-size:1.15rem;
  color:var(--text);
  letter-spacing:-.02em;
}
.nav-links{display:flex;gap:1.5rem;align-items:center}
.nav-links a{
  color:var(--text-secondary);
  font-size:.9rem;
  font-weight:500;
  transition:color .2s;
}
.nav-links a:hover{color:var(--text)}
.theme-toggle{
  background:none;border:1px solid var(--border);
  border-radius:50%;width:36px;height:36px;
  display:flex;align-items:center;justify-content:center;
  cursor:pointer;font-size:1.1rem;
  color:var(--text-secondary);
  transition:all .2s;
}
.theme-toggle:hover{color:var(--text);border-color:var(--text-secondary)}

/* === 首页 === */
.hero{
  padding:4rem 1.5rem 3rem;
  text-align:center;
  background:var(--hero-bg);
  border-bottom:1px solid var(--border);
}
.hero h1{
  font-size:2.5rem;
  font-weight:800;
  letter-spacing:-.03em;
  margin-bottom:.5rem;
  background:linear-gradient(135deg,var(--accent),#7c3aed);
  -webkit-background-clip:text;
  -webkit-text-fill-color:transparent;
  background-clip:text;
}
.hero p{
  font-size:1.1rem;
  color:var(--text-secondary);
  max-width:500px;
  margin:0 auto 1.5rem;
}
.hero-tags{
  display:flex;gap:.5rem;justify-content:center;flex-wrap:wrap;
}
.hero-tag{
  background:var(--bg-card);
  border:1px solid var(--border);
  padding:.35rem .85rem;
  border-radius:20px;
  font-size:.82rem;
  color:var(--text-secondary);
}

/* === 文章列表 === */
.section-title{
  font-size:1.3rem;
  font-weight:700;
  margin:3rem 0 1.5rem;
  display:flex;align-items:center;gap:.5rem;
}
.section-title::after{
  content:'';
  flex:1;
  height:1px;
  background:var(--border);
}
.article-grid{
  display:grid;
  grid-template-columns:repeat(auto-fill,minmax(320px,1fr));
  gap:1.25rem;
  margin-bottom:2rem;
}
.article-card{
  background:var(--bg-card);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:1.5rem;
  transition:all .2s;
  display:flex;flex-direction:column;
  gap:.6rem;
}
.article-card:hover{
  box-shadow:var(--shadow-lg);
  border-color:var(--accent);
  transform:translateY(-2px);
}
.article-card .cat{
  font-size:.75rem;
  font-weight:600;
  text-transform:uppercase;
  letter-spacing:.04em;
  color:var(--accent);
}
.article-card h3{
  font-size:1.1rem;
  margin:0;
  line-height:1.4;
}
.article-card h3 a{color:var(--text)}
.article-card h3 a:hover{color:var(--accent)}
.article-card .desc{
  font-size:.9rem;
  color:var(--text-secondary);
  line-height:1.5;
  flex:1;
}
.article-card .meta{
  font-size:.78rem;
  color:var(--text-muted);
  display:flex;gap:1rem;
}

/* === 分类标签 === */
.cat-tabs{
  display:flex;gap:.5rem;flex-wrap:wrap;margin:2rem 0 1rem;
}
.cat-tab{
  padding:.4rem 1rem;
  border-radius:20px;
  font-size:.85rem;
  cursor:pointer;
  border:1px solid var(--border);
  background:var(--bg-card);
  color:var(--text-secondary);
  transition:all .2s;
  white-space:nowrap;
}
.cat-tab:hover,.cat-tab.active{
  background:var(--accent);
  color:#fff;
  border-color:var(--accent);
}

/* === 文章页 === */
.article-header{
  padding:3rem 0 1.5rem;
  border-bottom:1px solid var(--border);
  margin-bottom:2rem;
}
.article-header .cat{
  font-size:.78rem;font-weight:600;color:var(--accent);
  text-transform:uppercase;letter-spacing:.04em;margin-bottom:.5rem;
}
.article-header h1{font-size:2.2rem;margin-bottom:.5rem}
.article-meta{
  display:flex;gap:1rem;color:var(--text-muted);font-size:.85rem;
  flex-wrap:wrap;
}
.article-body{font-size:1.05rem;line-height:1.85}
.article-body h2{margin-top:2em}
.article-body h3{margin-top:1.5em}

/* 文章内CTA卡片 */
.cta-card{
  background:var(--accent-light);
  border:1px solid var(--accent);
  border-radius:var(--radius);
  padding:1.5rem;
  margin:2rem 0;
  text-align:center;
}
.cta-card h4{margin:0 0 .5rem}
.cta-card p{color:var(--text-secondary);margin-bottom:1rem}
.cta-card .btn{display:inline-block}

/* 按钮 */
.btn{
  display:inline-block;
  padding:.6rem 1.5rem;
  background:var(--accent);
  color:#fff!important;
  border-radius:var(--radius-sm);
  font-weight:600;
  font-size:.9rem;
  transition:all .2s;
}
.btn:hover{background:var(--accent-hover);transform:translateY(-1px)}

/* === 页脚 === */
.footer{
  border-top:1px solid var(--border);
  padding:2rem 1.5rem;
  margin-top:4rem;
  text-align:center;
  color:var(--text-muted);
  font-size:.85rem;
}
.footer a{color:var(--text-secondary)}
.footer-links{display:flex;gap:1.5rem;justify-content:center;margin-top:.5rem}

/* === 响应式 === */
@media(max-width:768px){
  .hero h1{font-size:1.8rem}
  .hero{padding:2.5rem 1rem 2rem}
  .article-grid{grid-template-columns:1fr}
  .article-header h1{font-size:1.6rem}
  h1{font-size:1.6rem}
  .nav-links{gap:1rem}
}

/* === 面包屑 === */
.breadcrumb{
  font-size:.85rem;color:var(--text-muted);
  margin-bottom:.5rem;
}
.breadcrumb a{color:var(--text-secondary)}

/* === 相关文章 === */
.related-section{margin-top:3rem;padding-top:2rem;border-top:1px solid var(--border)}
.related-grid{
  display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));
  gap:1rem;margin-top:1rem;
}

/* === 订阅区域 === */
.newsletter{
  background:var(--bg-card);
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:2rem;
  text-align:center;
  margin:3rem 0;
}
.newsletter h3{margin:0 0 .5rem}
.newsletter p{color:var(--text-secondary);margin-bottom:1rem}
.newsletter-form{display:flex;gap:.5rem;max-width:400px;margin:0 auto}
.newsletter-form input{
  flex:1;padding:.55rem 1rem;
  border:1px solid var(--border);border-radius:var(--radius-sm);
  background:var(--bg);color:var(--text);font-size:.9rem;
}
.newsletter-form input:focus{outline:none;border-color:var(--accent)}