/* 28圈注册 · 共享样式 /assets/site.css */

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
body,h1,h2,h3,h4,h5,p,ul,ol,li,figure,blockquote,dl,dd{margin:0}
ul,ol{padding:0;list-style:none}
img,svg{display:block;max-width:100%;height:auto}
button{font:inherit;color:inherit;background:none;border:0;cursor:pointer}
input{font:inherit}
a{color:inherit}
hr{border:0}

:root{
  --ink-900:#0B1622;
  --ink-700:#14263A;
  --ink-500:#24405C;
  --paper-100:#F7F5F0;
  --paper-200:#EBE6DC;
  --stone-500:#6C7681;
  --signal-500:#E8551F;
  --signal-700:#B23A12;
  --celadon-500:#3FA98C;
  --moss-600:#4A6B4F;
  --clay-500:#B06A4A;
  --hair:rgba(11,22,34,.14);
  --hair-soft:rgba(11,22,34,.08);
  --hair-dark:rgba(247,245,240,.16);
  --on-dark:rgba(247,245,240,.78);
  --on-dark-soft:rgba(247,245,240,.52);
  --shell:1240px;
  --gutter:clamp(18px,4vw,32px);
  --masthead-h:64px;
  --radius:2px;
  --font-sans:"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Source Han Sans SC","Noto Sans CJK SC",system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
  --ease-out:cubic-bezier(.22,.61,.36,1);
}

body{
  background:var(--paper-100);
  color:var(--ink-900);
  font-family:var(--font-sans);
  font-size:17px;
  line-height:1.85;
  font-weight:400;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

h1,h2,h3,h4{font-weight:800;letter-spacing:.04em;line-height:1.12}
:focus-visible{outline:2px solid var(--signal-500);outline-offset:2px}

/* ---------- 排版工具 ---------- */
.h-display{font-size:clamp(2.4rem,6vw,5.2rem);font-weight:800;letter-spacing:.04em;line-height:1.12}
.h-section{font-size:clamp(1.6rem,3vw,2.6rem);font-weight:800;letter-spacing:.04em;line-height:1.16}
.lede{font-size:clamp(1rem,1.5vw,1.15rem);line-height:1.8;color:var(--ink-500);max-width:58ch}
.section--ink .lede{color:var(--on-dark)}
.eyebrow{display:inline-flex;align-items:center;gap:10px;font-size:12px;font-weight:600;letter-spacing:.16em;color:var(--signal-700)}
.eyebrow::before{content:"";display:block;width:22px;height:1px;background:currentColor}
.section--ink .eyebrow{color:var(--signal-500)}
.label{font-size:12px;letter-spacing:.12em;color:var(--stone-500)}
.numeral{font-size:clamp(3rem,10vw,7rem);font-weight:800;line-height:.86;letter-spacing:-.02em;font-variant-numeric:tabular-nums;color:rgba(11,22,34,.12);-webkit-text-stroke:1px rgba(11,22,34,.26)}
.numeral--solid{color:var(--signal-500);-webkit-text-stroke:0}
.section--ink .numeral{color:rgba(247,245,240,.1);-webkit-text-stroke-color:rgba(247,245,240,.28)}
.prose{max-width:66ch}
.prose p{margin-bottom:1.4em}
.prose h3{font-size:1.3rem;margin:1.8em 0 .6em;letter-spacing:.04em}
.prose ul{display:grid;gap:.5em;margin:0 0 1.4em}
.prose li{padding-left:20px;position:relative}
.prose li::before{content:"";position:absolute;left:0;top:.82em;width:10px;height:1px;background:var(--signal-500)}
.rule{height:1px;background:var(--hair);margin:0}
.rule--dark{background:var(--hair-dark)}

/* ---------- 布局 ---------- */
.shell{width:100%;max-width:var(--shell);margin:0 auto;padding:0 var(--gutter)}
.section{padding:clamp(48px,7vw,96px) 0}
.section--paper{background:var(--paper-100)}
.section--sand{background:var(--paper-200)}
.section--ink{background:var(--ink-900);color:var(--paper-100)}
.section--ink .label,.section--ink .prose li::before{color:var(--signal-500);background-color:var(--signal-500)}
.grid{display:grid;gap:clamp(16px,2.4vw,28px)}
.grid--2{grid-template-columns:repeat(2,minmax(0,1fr))}
.grid--3{grid-template-columns:repeat(3,minmax(0,1fr))}
.grid--4{grid-template-columns:repeat(4,minmax(0,1fr))}
.grid--split{grid-template-columns:repeat(2,minmax(0,1fr))}

/* ---------- 标签 / 面板 ---------- */
.tag{display:inline-flex;align-items:center;gap:6px;padding:3px 9px;border:1px solid var(--hair);font-size:12px;letter-spacing:.1em;color:var(--ink-500);background:rgba(255,255,255,.45)}
.tag--signal{border-color:var(--signal-500);color:var(--signal-700)}
.tag--ok{border-color:var(--celadon-500);color:#2C7D66}
.panel{padding:clamp(16px,2.2vw,26px);background:var(--paper-200);border-left:2px solid var(--signal-500)}

/* ---------- 框景 ---------- */
.frame{position:relative;padding:clamp(20px,4vw,48px);border:1px solid var(--hair);background:var(--paper-100)}
.frame--ink{border-color:var(--hair-dark);background:var(--ink-900);color:var(--paper-100)}
.frame--tight{padding:clamp(14px,2vw,24px)}
.frame__tick{position:absolute;width:9px;height:9px;border:1px solid var(--signal-500)}
.frame__tick--tl{top:-1px;left:-1px;border-right:0;border-bottom:0}
.frame__tick--tr{top:-1px;right:-1px;border-left:0;border-bottom:0}
.frame__tick--bl{bottom:-1px;left:-1px;border-right:0;border-top:0}
.frame__tick--br{bottom:-1px;right:-1px;border-left:0;border-top:0}
.frame__scale{position:absolute;left:12%;right:12%;height:5px;opacity:.55;background-image:repeating-linear-gradient(90deg,var(--signal-500) 0 1px,transparent 1px 20px)}
.frame__scale--top{top:0}
.frame__scale--bottom{bottom:0}

/* ---------- 图像容器 ---------- */
.media{display:block;margin:0}
.media__frame{position:relative;overflow:hidden;border:1px solid var(--hair);background:var(--paper-200)}
.media__inner{position:relative;width:100%;aspect-ratio:16/10;background:var(--paper-200)}
.media__inner>img{width:100%;height:100%;object-fit:cover}
.media__caption{margin-top:10px;font-size:12.5px;letter-spacing:.04em;color:var(--stone-500)}
.media--3x2 .media__inner{aspect-ratio:3/2}
.media--wide .media__inner{aspect-ratio:21/9}
.media--square .media__inner{aspect-ratio:1/1}
.media--tall .media__inner{aspect-ratio:4/5}
.media--geo .media__inner{background-color:var(--paper-200);background-image:linear-gradient(135deg,rgba(232,85,31,.16) 0 32%,transparent 32%),linear-gradient(0deg,rgba(63,169,140,.18) 0 46%,transparent 46%),repeating-linear-gradient(90deg,rgba(11,22,34,.12) 0 1px,transparent 1px 22px)}
.media--grid .media__inner{background-color:var(--paper-200);background-image:repeating-linear-gradient(0deg,rgba(11,22,34,.1) 0 1px,transparent 1px 28px),repeating-linear-gradient(90deg,rgba(11,22,34,.1) 0 1px,transparent 1px 28px)}
.media--texture .media__inner{background-color:var(--ink-700);background-image:radial-gradient(120% 80% at 20% 15%,rgba(74,107,79,.34),transparent 60%),radial-gradient(90% 70% at 85% 80%,rgba(176,106,74,.28),transparent 62%),radial-gradient(60% 60% at 55% 50%,rgba(63,169,140,.18),transparent 70%)}
.media--ink .media__frame{border-color:var(--hair-dark);background:var(--ink-700)}

/* ---------- 面包屑 ---------- */
.crumbs{display:flex;flex-wrap:wrap;align-items:center;gap:8px;padding:14px 0;font-size:12.5px;letter-spacing:.06em;color:var(--stone-500)}
.crumbs__link{text-decoration:none;border-bottom:1px solid var(--hair);transition:color .2s var(--ease-out),border-color .2s var(--ease-out)}
.crumbs__link:hover{color:var(--signal-700);border-bottom-color:var(--signal-500)}
.crumbs__sep{opacity:.5}
.crumbs__item--current{font-weight:600;color:var(--ink-900)}

/* ---------- 章节索引 ---------- */
.toc{position:sticky;top:calc(var(--masthead-h) + 18px);font-size:13.5px}
.toc__title{margin-bottom:10px;font-size:11px;letter-spacing:.18em;color:var(--stone-500)}
.toc__list{display:grid;gap:2px}
.toc__link{display:block;padding:6px 10px;border-left:2px solid var(--hair);color:var(--ink-500);text-decoration:none;transition:color .2s var(--ease-out),border-color .2s var(--ease-out)}
.toc__link:hover{color:var(--ink-900);border-left-color:var(--ink-500)}
.toc__link[aria-current="true"]{color:var(--signal-700);border-left-color:var(--signal-500);font-weight:700}

/* ---------- 按钮 ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:10px 17px;border:1px solid transparent;border-radius:var(--radius);font-size:14px;font-weight:600;letter-spacing:.06em;text-decoration:none;white-space:nowrap;transition:background-color .2s var(--ease-out),border-color .2s var(--ease-out),color .2s var(--ease-out)}
.btn--primary{background:var(--signal-700);border-color:var(--signal-700);color:#fff}
.btn--primary:hover{background:var(--signal-500);border-color:var(--signal-500)}
.btn--line{border-color:rgba(247,245,240,.3);color:var(--paper-100);background:transparent}
.btn--line:hover{border-color:var(--signal-500);color:#fff}
.btn--sm{padding:7px 13px;font-size:13px}

/* ---------- 跳转链 ---------- */
.skip-link{position:absolute;left:var(--gutter);top:-80px;z-index:120;padding:10px 16px;background:var(--signal-700);color:#fff;font-size:14px;text-decoration:none;transition:top .2s var(--ease-out)}
.skip-link:focus{top:10px}

/* ---------- 命令栏 ---------- */
.masthead{position:sticky;top:0;z-index:60;background:var(--ink-900);color:var(--paper-100);border-bottom:1px solid var(--hair-dark)}
.masthead__rail{background-image:repeating-linear-gradient(90deg,rgba(247,245,240,.05) 0 1px,transparent 1px 96px)}
.masthead__inner{display:grid;grid-template-columns:auto minmax(0,1fr) auto;align-items:center;gap:16px;width:100%;max-width:var(--shell);min-height:var(--masthead-h);margin:0 auto;padding:0 var(--gutter);transition:min-height .24s var(--ease-out)}
.masthead.is-compact .masthead__inner{min-height:48px}
.masthead.is-compact .version-chip__k{display:none}
.masthead.is-compact .nav__link{padding-top:6px;padding-bottom:6px}

.brand{display:inline-flex;align-items:center;gap:10px;padding:6px 0;text-decoration:none;color:inherit}
.brand__name{font-size:clamp(15px,1.5vw,17px);font-weight:800;letter-spacing:.06em}
.version-chip{display:inline-flex;align-items:baseline;gap:5px;padding:2px 7px;border:1px solid var(--signal-500);color:var(--signal-500);font-size:11px;letter-spacing:.14em;white-space:nowrap}
.version-chip__k{font-size:9px;letter-spacing:.18em;opacity:.85}
.version-chip__v{font-weight:700;letter-spacing:.06em;font-variant-numeric:tabular-nums}
.version-chip--footer{margin:2px 0 6px}

.nav{display:flex;justify-content:center}
.nav__list{display:flex;flex-wrap:wrap;justify-content:center;gap:2px}
.nav__link{display:inline-flex;align-items:baseline;gap:6px;padding:9px 11px;border-bottom:2px solid transparent;color:rgba(247,245,240,.7);font-size:14px;letter-spacing:.04em;text-decoration:none;transition:color .2s var(--ease-out),border-color .2s var(--ease-out)}
.nav__link:hover{color:#fff;border-bottom-color:rgba(232,85,31,.55)}
.nav__link[aria-current="page"]{color:#fff;font-weight:700;border-bottom-color:var(--signal-500)}
.nav__idx{font-size:10px;letter-spacing:.1em;color:var(--on-dark-soft);font-variant-numeric:tabular-nums}
.nav__link[aria-current="page"] .nav__idx{color:var(--signal-500)}
.nav__label{white-space:nowrap}

.masthead__tools{display:flex;align-items:center;gap:8px;justify-self:end}
.search-toggle__text{white-space:nowrap}

.nav-toggle{display:none;align-items:center;gap:8px;padding:7px 11px;border:1px solid rgba(247,245,240,.3);border-radius:var(--radius);font-size:13px;letter-spacing:.08em;color:var(--paper-100)}
.nav-toggle:hover{border-color:var(--signal-500)}
.nav-toggle__bars{display:grid;gap:3px;width:14px}
.nav-toggle__bars i{display:block;height:1px;background:currentColor}
.nav-toggle__text{white-space:nowrap}

/* ---------- 站内搜索面板 ---------- */
.search{position:absolute;left:0;right:0;top:100%;background:var(--ink-700);border-bottom:1px solid var(--hair-dark);box-shadow:0 22px 34px rgba(11,22,34,.38)}
.search[hidden]{display:none}
.search__inner{display:grid;gap:12px;width:100%;max-width:var(--shell);margin:0 auto;padding:18px var(--gutter) 22px}
.search__label{font-size:12px;letter-spacing:.14em;color:var(--on-dark-soft)}
.search__input{width:100%;padding:11px 13px;background:rgba(247,245,240,.06);border:1px solid var(--hair-dark);border-radius:var(--radius);color:var(--paper-100);font-size:15px;letter-spacing:.02em}
.search__input::placeholder{color:rgba(247,245,240,.42)}
.search__input:focus-visible{outline:2px solid var(--signal-500);outline-offset:1px}
.search__chips{display:flex;flex-wrap:wrap;gap:6px}
.chip{padding:5px 12px;border:1px solid var(--hair-dark);border-radius:999px;font-size:12px;letter-spacing:.1em;color:var(--on-dark);transition:border-color .2s var(--ease-out),color .2s var(--ease-out),background-color .2s var(--ease-out)}
.chip:hover{border-color:var(--signal-500);color:#fff}
.chip[aria-pressed="true"]{border-color:var(--signal-500);background:rgba(232,85,31,.14);color:#fff}
.search__list{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:8px}
.search__item{margin:0}
.search__link{display:flex;align-items:baseline;gap:9px;padding:10px 12px;border:1px solid var(--hair-dark);color:var(--paper-100);font-size:14px;text-decoration:none;transition:border-color .2s var(--ease-out),background-color .2s var(--ease-out)}
.search__link:hover{border-color:var(--signal-500);background:rgba(247,245,240,.05)}
.search__group{font-size:10px;letter-spacing:.16em;color:var(--signal-500);font-variant-numeric:tabular-nums}
.search__title{letter-spacing:.03em}
.search__empty{grid-column:1/-1;padding:10px 12px;border:1px dashed var(--hair-dark);font-size:13px;color:var(--on-dark-soft)}
.search__hint{font-size:12px;color:var(--on-dark-soft)}

/* ---------- 阅读进度 ---------- */
.progress{position:absolute;left:0;right:0;bottom:0;height:2px;background:rgba(247,245,240,.1);pointer-events:none}
.progress__bar{display:block;width:0;height:100%;background:var(--signal-500);transition:width .15s linear}

/* ---------- 页脚 ---------- */
.site-footer{background:var(--ink-900);color:var(--on-dark);border-top:1px solid var(--hair-dark);background-image:repeating-linear-gradient(90deg,rgba(247,245,240,.04) 0 1px,transparent 1px 96px);padding-top:clamp(40px,6vw,72px)}
.site-footer__rail{width:100%;max-width:var(--shell);margin:0 auto;padding:0 var(--gutter)}
.site-footer__grid{display:grid;grid-template-columns:1.5fr 1fr 1fr 1.3fr;gap:clamp(20px,3vw,40px);padding-bottom:36px}
.footer-col{display:grid;gap:10px;align-content:start}
.footer-col__title{font-size:11px;letter-spacing:.18em;color:var(--on-dark-soft);padding-bottom:8px;border-bottom:1px solid var(--hair-dark)}
.footer__brand{font-size:19px;font-weight:800;letter-spacing:.06em;color:var(--paper-100)}
.footer__note{max-width:34ch;font-size:13.5px;line-height:1.75;color:var(--on-dark-soft)}
.footer__list{display:grid;gap:8px}
.footer__list--contact{gap:12px}
.footer__link{display:inline-block;font-size:14px;color:var(--on-dark);text-decoration:none;border-bottom:1px solid transparent;transition:color .2s var(--ease-out),border-color .2s var(--ease-out)}
.footer__link:hover{color:#fff;border-bottom-color:var(--signal-500)}
.footer__key{display:block;font-size:11px;letter-spacing:.16em;color:var(--on-dark-soft)}
.footer__value{display:block;font-size:14px;color:var(--paper-100);word-break:break-word;font-variant-numeric:tabular-nums}
.site-footer__bottom{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:10px 24px;padding:18px 0 26px;border-top:1px solid var(--hair-dark)}
.footer__meta{font-size:12.5px;letter-spacing:.06em;color:var(--on-dark-soft)}
.footer__sign{font-variant-numeric:tabular-nums}

/* ---------- 动效 / 返回顶部 ---------- */
.reveal{opacity:0;transform:translateY(12px);transition:opacity .3s var(--ease-out),transform .3s var(--ease-out)}
.reveal.is-visible{opacity:1;transform:none}
.to-top{position:fixed;right:16px;bottom:16px;z-index:70;padding:9px 14px;border:1px solid var(--hair);background:var(--paper-100);color:var(--ink-900);font-size:12.5px;letter-spacing:.1em;opacity:0;visibility:hidden;transform:translateY(6px);transition:opacity .24s var(--ease-out),transform .24s var(--ease-out),visibility .24s var(--ease-out)}
.to-top.is-visible{opacity:1;visibility:visible;transform:none}

@media (prefers-reduced-motion:reduce){
  .reveal{opacity:1;transform:none;transition:none}
  .progress__bar{transition:none}
  .to-top{transition:none}
  .masthead__inner{transition:none}
}

/* ---------- 响应式 ---------- */
@media (max-width:1080px){
  .nav__link{padding:8px 8px;font-size:13.5px}
  .site-footer__grid{grid-template-columns:repeat(2,minmax(0,1fr))}
}

@media (max-width:900px){
  .masthead__inner{grid-template-columns:auto auto;justify-content:space-between;gap:10px}
  .nav-toggle{display:inline-flex}
  .nav{position:absolute;top:100%;left:0;right:0;display:none;justify-content:flex-start;background:var(--ink-700);border-bottom:1px solid var(--hair-dark);box-shadow:0 20px 32px rgba(11,22,34,.4)}
  .nav[data-open]{display:block}
  .nav__list{flex-direction:column;flex-wrap:nowrap;justify-content:flex-start;gap:0;padding:6px var(--gutter) 14px}
  .nav__item{width:100%}
  .nav__link{display:flex;width:100%;padding:13px 0;border-bottom:1px solid var(--hair-dark);font-size:15px}
  .nav__link[aria-current="page"]{border-bottom-color:var(--signal-500)}
  .grid--3,.grid--4{grid-template-columns:repeat(2,minmax(0,1fr))}
  .toc{position:static}
}

@media (max-width:640px){
  body{font-size:16px}
  .masthead__tools{gap:6px}
  .search-toggle__text{display:none}
  .search-toggle{padding:7px 10px}
  .search-toggle::before{content:"搜索";font-size:13px;letter-spacing:.08em}
  .search__inner{padding:14px var(--gutter) 18px}
  .search__list{grid-template-columns:1fr}
  .site-footer__grid{grid-template-columns:1fr;gap:26px}
  .grid--2,.grid--3,.grid--4,.grid--split{grid-template-columns:1fr}
  .frame{padding:18px}
  .to-top{right:12px;bottom:12px}
}