/* =========================================================
   28圈指南 · /assets/site.css
   共享外壳：reset / 变量 / 中文排版 / 头部 / 页脚 / 通用组件
   ========================================================= */

/* ---------- 0. Reset ---------- */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body{margin:0}
img,svg,video{display:block;max-width:100%}
button,input,select,textarea{font:inherit;color:inherit}
button{background:none;border:0;padding:0}
h1,h2,h3,h4,h5,h6,p,figure,blockquote,dl,dd{margin:0}
a{color:inherit}
table{border-collapse:collapse}
[hidden]{display:none !important}

/* ---------- 1. 变量 ---------- */
:root{
  --paper:#F8F6F0;
  --mist:#7C9188;
  --indigo-wash:#E7EAF3;
  --indigo:#2C3A5B;
  --haze:#DCE5DE;
  --night:#182238;
  --ink:#12191F;
  --gray:#6E7671;
  --orange:#E4682E;
  --orange-soft:#FBE0D2;
  --orange-deep:#C9551F;

  --font-serif:"Noto Serif SC","Source Han Serif SC","Songti SC",serif;
  --font-sans:"Noto Sans SC","Source Han Sans SC","PingFang SC","Microsoft YaHei",sans-serif;
  --font-mono:ui-monospace,"JetBrains Mono","Roboto Mono",Menlo,Consolas,monospace;

  --fs-12:.75rem;
  --fs-13:.8125rem;
  --fs-15:.9375rem;
  --fs-17:1.0625rem;
  --fs-20:1.25rem;
  --fs-26:1.625rem;
  --fs-34:2.125rem;
  --fs-46:2.875rem;
  --fs-62:3.875rem;

  --fs-hero:clamp(2.4rem,5.2vw,4.2rem);
  --fs-section:clamp(1.5rem,2.6vw,2.2rem);
  --fs-chapter:clamp(1.15rem,1.6vw,1.4rem);

  --rail-w:224px;
  --topbar-h:64px;
  --maxw:1240px;
  --gut:clamp(18px,4vw,40px);
  --ease:cubic-bezier(.22,.61,.36,1);
  --rule:rgba(44,58,91,.14);
  --measure:42em;
}

/* ---------- 2. 中文排版与页面基底 ---------- */
body{
  min-height:100vh;
  display:flex;
  flex-direction:column;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--font-sans);
  font-size:var(--fs-17);
  line-height:1.75;
  font-weight:400;
  -webkit-font-smoothing:antialiased;
}
h1,h2,h3,h4{
  font-family:var(--font-serif);
  color:var(--indigo);
  font-weight:700;
  line-height:1.15;
  letter-spacing:-.01em;
}
h1{font-size:var(--fs-hero)}
h2{font-size:var(--fs-section)}
h3{font-size:var(--fs-chapter);font-weight:600}
h4{font-size:var(--fs-17);font-family:var(--font-sans);font-weight:700;letter-spacing:0;line-height:1.4}
p{margin:0 0 1.2em}
p:last-child{margin-bottom:0}
a{color:var(--indigo);text-decoration-color:rgba(228,104,46,.45);text-underline-offset:3px}
a:hover{text-decoration-color:var(--orange)}
strong{font-weight:700}
.mono,code,kbd,samp{
  font-family:var(--font-mono);
  font-weight:500;
  font-size:.94em;
  letter-spacing:.01em;
}
:focus-visible{outline:2px solid var(--orange);outline-offset:2px;border-radius:2px}

/* ---------- 3. 容器 / 网格 / 文本流 ---------- */
.wrap{
  width:100%;
  max-width:var(--maxw);
  margin-inline:auto;
  padding-inline:var(--gut);
}
.prose{max-width:var(--measure)}
.prose p{margin-bottom:1.2em}
.grid{display:grid;gap:clamp(20px,3vw,36px)}
.grid--5-7{grid-template-columns:minmax(200px,5fr) 7fr}
.grid--4-8{grid-template-columns:minmax(200px,4fr) 8fr}
.grid--auto{grid-template-columns:repeat(auto-fit,minmax(240px,1fr))}
.divider{height:1px;background:var(--rule);border:0;margin:clamp(32px,5vw,64px) 0}
.band{background:var(--haze)}
.band--wash{background:var(--indigo-wash)}

/* ---------- 4. 按钮 / 标签 / 代码块 ---------- */
.btn{
  display:inline-flex;
  align-items:center;
  gap:8px;
  font-family:var(--font-sans);
  font-size:var(--fs-15);
  font-weight:600;
  line-height:1;
  padding:13px 22px;
  border-radius:3px;
  border:1px solid transparent;
  text-decoration:none;
  cursor:pointer;
  transition:background 200ms var(--ease),color 200ms var(--ease),border-color 200ms var(--ease);
}
.btn--primary{background:var(--orange);color:#fff}
.btn--primary:hover{background:var(--orange-deep);color:#fff}
.btn--ghost{border-color:rgba(44,58,91,.28);color:var(--indigo);background:transparent}
.btn--ghost:hover{border-color:var(--orange);color:var(--orange);background:var(--orange-soft)}

.tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  font-weight:500;
  padding:4px 9px;
  border-radius:2px;
  background:var(--haze);
  color:var(--indigo);
  text-decoration:none;
}
.tag--accent{background:var(--orange-soft);color:var(--orange-deep)}

.code{
  position:relative;
  font-family:var(--font-mono);
  font-size:var(--fs-13);
  font-weight:500;
  line-height:1.75;
  background:var(--night);
  color:#D8DEE6;
  border-radius:4px;
  padding:20px 92px 20px 18px;
  overflow-x:auto;
  white-space:pre;
}
.code__copy{
  position:absolute;
  right:12px;
  top:12px;
  font-family:var(--font-sans);
  font-size:var(--fs-12);
  font-weight:600;
  padding:7px 12px;
  border:1px solid rgba(216,222,230,.4);
  border-radius:2px;
  color:#D8DEE6;
  cursor:pointer;
  transition:background 200ms var(--ease),color 200ms var(--ease),border-color 200ms var(--ease);
}
.code__copy:hover{border-color:var(--orange);color:var(--orange)}
.code__copy[data-copied]{background:var(--orange);border-color:var(--orange);color:#fff}

/* ---------- 5. 头部：侧边轨道 / 移动抽屉 ---------- */
.skip-link{
  position:fixed;
  left:12px;
  top:-90px;
  z-index:200;
  background:var(--orange);
  color:#fff;
  font-size:var(--fs-13);
  font-weight:600;
  padding:11px 18px;
  border-radius:3px;
  text-decoration:none;
  transition:top 180ms var(--ease);
}
.skip-link:focus{top:12px;outline:none}

.site-header{
  position:fixed;
  top:0;
  left:0;
  bottom:0;
  z-index:80;
  width:var(--rail-w);
  display:flex;
  flex-direction:column;
  padding:26px 20px 20px;
  overflow-y:auto;
  overscroll-behavior:contain;
  background:
    linear-gradient(180deg,rgba(220,229,222,.62),rgba(231,234,243,.42) 42%,rgba(248,246,240,.85)),
    var(--paper);
  border-right:1px solid var(--rule);
}

.rail-top{display:flex;align-items:flex-start;gap:12px}
.brand{
  display:flex;
  align-items:center;
  gap:10px;
  text-decoration:none;
  color:var(--indigo);
}
.brand__mark{
  position:relative;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  min-width:36px;
  height:30px;
  padding:0 8px;
  background:var(--indigo);
  color:var(--paper);
  font-family:var(--font-mono);
  font-size:var(--fs-13);
  font-weight:500;
  letter-spacing:.04em;
  border-radius:2px;
}
.brand__mark::after{
  content:"";
  position:absolute;
  right:0;
  bottom:0;
  width:9px;
  height:9px;
  background:var(--orange);
  clip-path:polygon(100% 0,100% 100%,0 100%);
}
.brand__text{display:flex;flex-direction:column;gap:1px;min-width:0}
.brand__name{
  font-family:var(--font-serif);
  font-size:var(--fs-20);
  font-weight:700;
  letter-spacing:-.01em;
  color:var(--indigo);
  line-height:1.2;
}
.brand__domain{
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  font-weight:500;
  color:var(--gray);
  letter-spacing:.01em;
  line-height:1.4;
}
.brand__tagline{
  margin:14px 0 0;
  font-size:var(--fs-13);
  color:var(--gray);
  line-height:1.6;
  letter-spacing:.01em;
}

.nav-toggle{
  display:none;
  align-items:center;
  gap:9px;
  padding:9px 12px;
  border:1px solid var(--rule);
  border-radius:3px;
  color:var(--indigo);
  font-size:var(--fs-13);
  font-weight:600;
  cursor:pointer;
  background:rgba(255,255,255,.5);
  transition:border-color 200ms var(--ease),color 200ms var(--ease);
}
.nav-toggle:hover{border-color:var(--orange);color:var(--orange)}
.nav-toggle__lines{
  position:relative;
  display:block;
  width:16px;
  height:2px;
  background:currentColor;
  border-radius:1px;
}
.nav-toggle__lines::before,
.nav-toggle__lines::after{
  content:"";
  position:absolute;
  left:0;
  width:16px;
  height:2px;
  background:currentColor;
  border-radius:1px;
  transition:transform 200ms var(--ease),top 200ms var(--ease);
}
.nav-toggle__lines::before{top:-5px}
.nav-toggle__lines::after{top:5px}
.site-header[data-open] .nav-toggle__lines{background:transparent}
.site-header[data-open] .nav-toggle__lines::before{top:0;transform:rotate(45deg)}
.site-header[data-open] .nav-toggle__lines::after{top:0;transform:rotate(-45deg)}

.rail-body{
  display:flex;
  flex-direction:column;
  flex:1 1 auto;
  min-height:0;
  margin-top:24px;
}
.rail-nav{flex:1 1 auto}
.rail-list{list-style:none;margin:0;padding:0;display:grid;gap:2px}
.rail-list__item{margin:0;padding:0}
.rail-link{
  position:relative;
  display:flex;
  align-items:center;
  gap:10px;
  padding:10px 12px 10px 14px;
  border-radius:3px;
  text-decoration:none;
  color:var(--indigo);
  font-size:var(--fs-15);
  font-weight:500;
  transition:background 200ms var(--ease),color 200ms var(--ease);
}
.rail-link::before{
  content:"";
  position:absolute;
  left:0;
  top:50%;
  width:0;
  height:1px;
  background:var(--orange);
  transform:translateY(-50%);
  transition:width 220ms var(--ease);
}
.rail-link__idx{
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  font-weight:500;
  color:var(--gray);
  letter-spacing:.04em;
}
.rail-link__label{flex:1 1 auto}
.rail-link:hover{background:var(--haze)}
.rail-link:hover::before{width:8px}
.rail-link[aria-current="page"]{
  background:linear-gradient(90deg,var(--orange-soft),rgba(251,224,210,0));
  color:var(--indigo);
  font-weight:700;
}
.rail-link[aria-current="page"]::before{width:16px}
.rail-link[aria-current="page"] .rail-link__idx{color:var(--orange-deep)}

.rail-tools{
  margin-top:auto;
  padding-top:20px;
  border-top:1px solid var(--rule);
  display:grid;
  gap:12px;
}
.rail-search{
  display:flex;
  flex-direction:column;
  gap:3px;
  padding:11px 13px;
  border:1px solid var(--rule);
  border-radius:3px;
  background:rgba(220,229,222,.6);
  -webkit-backdrop-filter:blur(8px);
  backdrop-filter:blur(8px);
  text-decoration:none;
  color:var(--indigo);
  transition:border-color 200ms var(--ease),background 200ms var(--ease);
}
.rail-search:hover{border-color:var(--orange);background:var(--orange-soft)}
.rail-search__label{font-size:var(--fs-13);font-weight:600}
.rail-search__meta{
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  font-weight:500;
  color:var(--gray);
  letter-spacing:.01em;
}
.bookmark-strip{
  display:flex;
  align-items:center;
  gap:6px;
  overflow-x:auto;
  padding-bottom:2px;
  scrollbar-width:none;
}
.bookmark-strip::-webkit-scrollbar{display:none}
.bookmark-strip__cap{
  flex:0 0 auto;
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  color:var(--gray);
  letter-spacing:.04em;
}
.bookmark-strip__link{
  flex:0 0 auto;
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  font-weight:500;
  padding:5px 9px;
  border-radius:2px;
  background:var(--haze);
  color:var(--indigo);
  text-decoration:none;
  border-bottom:2px solid var(--orange);
  transition:background 200ms var(--ease);
}
.bookmark-strip__link:hover{background:var(--orange-soft)}

.nav-scrim{
  position:fixed;
  inset:0;
  z-index:-1;
  background:rgba(18,25,31,.12);
  opacity:0;
  visibility:hidden;
  pointer-events:none;
  transition:opacity 200ms var(--ease),visibility 200ms linear;
}
.site-header[data-open] .nav-scrim{opacity:1;visibility:visible;pointer-events:auto}

/* ---------- 6. 页脚 ---------- */
.site-footer{
  position:relative;
  margin-top:auto;
  background:var(--night);
  color:#D8DEE6;
  overflow:hidden;
}
.site-footer::before{
  content:"";
  position:absolute;
  inset:0;
  background:radial-gradient(620px 320px at 10% -20%,rgba(124,145,136,.30),transparent 70%),
             radial-gradient(520px 300px at 95% 110%,rgba(228,104,46,.14),transparent 72%);
  pointer-events:none;
}
.site-footer__fold{
  position:absolute;
  top:0;
  right:0;
  width:72px;
  height:72px;
  background:var(--orange);
  clip-path:polygon(100% 0,100% 100%,0 0);
  opacity:.92;
}
.site-footer .wrap{position:relative;z-index:1}
.site-footer__grid{
  display:grid;
  grid-template-columns:1.5fr 1fr 1fr 1.4fr;
  gap:clamp(24px,3vw,48px);
  padding:clamp(48px,6vw,76px) 0 clamp(24px,3vw,34px);
}
.site-footer__brand{display:flex;flex-direction:column;align-items:flex-start;gap:16px}
.brand--invert .brand__mark{background:var(--orange);color:#fff}
.brand--invert .brand__mark::after{background:var(--paper)}
.brand--invert .brand__name{color:var(--paper)}
.brand--invert .brand__domain{color:rgba(216,222,230,.72)}
.site-footer__tagline{
  margin:0;
  font-family:var(--font-serif);
  font-size:var(--fs-20);
  font-weight:600;
  line-height:1.4;
  color:rgba(248,246,240,.86);
  letter-spacing:-.01em;
}
.site-footer__col{min-width:0}
.site-footer__title{
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  font-weight:500;
  letter-spacing:.08em;
  color:var(--orange);
  margin:0 0 16px;
  line-height:1.2;
}
.site-footer__list{list-style:none;margin:0;padding:0;display:grid;gap:10px}
.site-footer__list a{
  font-size:var(--fs-15);
  color:rgba(216,222,230,.86);
  text-decoration:none;
  border-bottom:1px solid transparent;
  transition:color 200ms var(--ease),border-color 200ms var(--ease);
}
.site-footer__list a:hover{color:#fff;border-bottom-color:var(--orange)}
.site-footer__meta{list-style:none;margin:0;padding:0;display:grid;gap:12px}
.site-footer__meta li{display:grid;grid-template-columns:44px 1fr;gap:10px;align-items:baseline}
.site-footer__label{
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  color:var(--mist);
  letter-spacing:.04em;
}
.site-footer__value{
  font-family:var(--font-mono);
  font-size:var(--fs-13);
  font-weight:500;
  color:rgba(248,246,240,.92);
  word-break:break-word;
  line-height:1.65;
}
.site-footer__note{
  margin:16px 0 0;
  font-size:var(--fs-13);
  line-height:1.7;
  color:rgba(216,222,230,.62);
}
.site-footer__base{
  display:flex;
  flex-wrap:wrap;
  gap:10px 28px;
  justify-content:space-between;
  align-items:center;
  padding:22px 0 30px;
  border-top:1px solid rgba(216,222,230,.16);
}
.site-footer__copy{
  margin:0;
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  font-weight:500;
  color:rgba(216,222,230,.72);
  letter-spacing:.01em;
}
.site-footer__line{
  margin:0;
  font-size:var(--fs-13);
  color:rgba(216,222,230,.6);
}

/* ---------- 7. 通用内容组件 ---------- */
.crumbs{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  list-style:none;
  margin:0 0 24px;
  padding:0;
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  font-weight:500;
  color:var(--gray);
}
.crumbs li{display:flex;align-items:center}
.crumbs li+li::before{content:"/";margin:0 10px;color:var(--mist)}
.crumbs a{color:var(--gray);text-decoration:none;transition:color 200ms var(--ease)}
.crumbs a:hover{color:var(--orange)}
.crumbs [aria-current="page"]{color:var(--indigo)}

.media{
  position:relative;
  overflow:hidden;
  border-radius:3px;
  background:linear-gradient(145deg,var(--haze),var(--indigo-wash));
  margin:0;
}
.media img,.media video,.media__img{width:100%;height:100%;object-fit:cover;display:block}
.media--wide{aspect-ratio:21/9}
.media--cover{aspect-ratio:16/10}
.media--square{aspect-ratio:1/1}
.media--tall{aspect-ratio:3/4}
.media__cap{
  position:absolute;
  left:0;
  right:0;
  bottom:0;
  padding:12px 14px;
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  font-weight:500;
  color:#fff;
  background:linear-gradient(to top,rgba(24,34,56,.84),rgba(24,34,56,0));
}
.media__fold{
  position:absolute;
  right:0;
  bottom:0;
  width:44px;
  height:44px;
  background:var(--orange);
  clip-path:polygon(100% 0,100% 100%,0 100%);
  pointer-events:none;
}

.timeline{position:relative;list-style:none;margin:0;padding:0 0 0 26px}
.timeline::before{
  content:"";
  position:absolute;
  left:4px;
  top:10px;
  bottom:10px;
  width:1px;
  background:rgba(44,58,91,.18);
}
.timeline__item{position:relative;padding-bottom:26px}
.timeline__item:last-child{padding-bottom:0}
.timeline__item::before{
  content:"";
  position:absolute;
  left:-26px;
  top:8px;
  width:9px;
  height:9px;
  box-sizing:border-box;
  border-radius:50%;
  background:var(--paper);
  border:2px solid var(--mist);
}
.timeline__item--now::before{border-color:var(--orange);background:var(--orange)}

.tagwall{display:flex;flex-wrap:wrap;gap:8px}
.tagwall__item{
  font-family:var(--font-mono);
  font-size:var(--fs-12);
  font-weight:500;
  padding:6px 11px;
  border-radius:2px;
  background:var(--haze);
  color:var(--indigo);
  text-decoration:none;
  border-bottom:2px solid transparent;
  cursor:pointer;
  transition:opacity 200ms var(--ease),background 200ms var(--ease),border-color 200ms var(--ease);
}
.tagwall__item:hover{background:var(--orange-soft)}
.tagwall.is-filtering .tagwall__item{opacity:.45}
.tagwall.is-filtering .tagwall__item.is-active{
  opacity:1;
  background:var(--orange-soft);
  border-bottom-color:var(--orange);
}

/* 滚动显现协议 */
[data-reveal]{transition:opacity 380ms var(--ease),transform 380ms var(--ease)}
html.js [data-reveal]:not(.is-visible){opacity:0;transform:translateY(16px)}

/* ---------- 8. 响应式：桌面端外壳 ---------- */
@media (min-width:1024px){
  body{padding-left:var(--rail-w)}
  .skip-link{left:calc(var(--rail-w) + 16px)}
}

/* ---------- 9. 响应式：移动端抽屉 ---------- */
@media (max-width:1023px){
  body{padding-top:var(--topbar-h)}

  .site-header{
    top:0;
    left:0;
    right:0;
    bottom:auto;
    width:auto;
    padding:0;
    overflow:visible;
    background:rgba(248,246,240,.94);
    -webkit-backdrop-filter:blur(14px);
    backdrop-filter:blur(14px);
    border-right:0;
    border-bottom:1px solid var(--rule);
  }
  .rail-top{
    display:flex;
    align-items:center;
    gap:12px;
    height:var(--topbar-h);
    padding:0 var(--gut);
  }
  .brand__tagline{display:none}
  .nav-toggle{display:inline-flex;margin-left:auto}

  .rail-body{
    position:absolute;
    top:100%;
    left:0;
    right:0;
    margin:0;
    max-height:calc(100vh - var(--topbar-h));
    overflow-y:auto;
    padding:12px var(--gut) 24px;
    background:var(--paper);
    border-bottom:1px solid var(--rule);
    box-shadow:0 20px 44px rgba(24,34,56,.14);
    opacity:0;
    visibility:hidden;
    transform:translateY(-10px);
    transition:opacity 200ms var(--ease),transform 200ms var(--ease),visibility 200ms linear;
  }
  .site-header[data-open] .rail-body{
    opacity:1;
    visibility:visible;
    transform:none;
  }
  .rail-nav{flex:0 0 auto}
  .rail-link{font-size:var(--fs-17);padding:13px 12px 13px 14px}
  .rail-tools{margin-top:20px}

  .site-footer__grid{grid-template-columns:1fr 1fr}
  .site-footer__brand{grid-column:1 / -1}
  .site-footer__contact{grid-column:1 / -1}
}

@media (max-width:640px){
  :root{--topbar-h:58px}
  .site-footer__grid{grid-template-columns:1fr;gap:28px}
  .site-footer__brand,.site-footer__contact{grid-column:auto}
  .site-footer__base{flex-direction:column;align-items:flex-start}
  .media__fold{width:32px;height:32px}
}

/* ---------- 10. 降低动效 ---------- */
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{
    animation-duration:.01ms !important;
    animation-iteration-count:1 !important;
    transition-duration:120ms !important;
    transition-property:opacity,color,background-color,border-color,visibility !important;
  }
  html.js [data-reveal]:not(.is-visible){opacity:1;transform:none}
  .rail-link::before{transition:none}
  .nav-scrim{transition:opacity 120ms linear,visibility 120ms linear}
}