/* ===== 1. reset ===== */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;text-size-adjust:100%}
body,h1,h2,h3,h4,h5,p,ul,ol,dl,dd,figure,blockquote{margin:0}
ul,ol{padding:0;list-style:none}
img,svg,video{display:block;max-width:100%;height:auto}
button,input,select,textarea{font:inherit;color:inherit}
button{background:none;border:0;padding:0;cursor:pointer}
a{color:inherit;text-decoration:none}
table{border-collapse:collapse;width:100%}
summary{list-style:none}

/* ===== 2. tokens ===== */
:root{
  --lake:#16697A;
  --lake-deep:#0E4A57;
  --lake-pale:#D6E8EC;
  --ochre:#A85B2A;
  --ochre-pale:#E8CDBB;
  --flame:#E4762F;
  --turq:#2E8B7A;
  --paper:#FBF7F0;
  --paper-2:#F4EEE4;
  --ink:#221C18;
  --note:#5C7480;
  --rule:#D8D2C6;
  --font-display:"Noto Sans SC","Source Han Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  --font-body:"PingFang SC","Microsoft YaHei","Noto Sans SC","Hiragino Sans GB",sans-serif;
  --font-mono:"IBM Plex Mono","JetBrains Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --shadow-1:0 1px 0 rgba(34,28,24,.06);
  --shadow-2:0 18px 30px -26px rgba(34,28,24,.55);
  --ease:cubic-bezier(.2,.7,.2,1);
  --dur:220ms;
  --w:1260px;
  --gutter:clamp(18px,4vw,56px);
}

/* ===== 3. 中文排版与基础 ===== */
html{background:var(--paper)}
body{
  background:var(--paper);
  color:var(--ink);
  font-family:var(--font-body);
  font-size:clamp(16px,.5vw + 14.2px,18px);
  line-height:1.85;
  letter-spacing:.01em;
  overflow-wrap:break-word;
  -webkit-font-smoothing:antialiased;
}
h1,h2,h3,h4{font-family:var(--font-display);color:var(--ink);text-wrap:balance}
h1{font-weight:900;font-size:clamp(32px,5.6vw,76px);line-height:1.04;letter-spacing:-.02em}
h2{font-weight:700;font-size:clamp(24px,2.6vw,36px);line-height:1.25;letter-spacing:-.01em}
h3{font-weight:700;font-size:clamp(19px,1.5vw,24px);line-height:1.35;letter-spacing:-.005em}
h4{font-weight:700;font-size:18px;line-height:1.45}
p,li{text-wrap:pretty}
strong{font-weight:700}
[id]{scroll-margin-top:92px}
::selection{background:var(--lake-pale);color:var(--lake-deep)}

:focus-visible{outline:2px solid var(--ochre);outline-offset:3px;border-radius:2px}

/* ===== 4. 跳转链接 ===== */
.skip-link{
  position:absolute;left:var(--gutter);top:10px;z-index:120;
  display:inline-block;padding:10px 18px;border-radius:2px;
  background:var(--lake-deep);color:var(--paper);
  font-size:14px;font-weight:700;
  transform:translateY(-240%);
  transition:transform 180ms var(--ease);
}
.skip-link:focus,.skip-link:focus-visible{transform:translateY(0)}

/* ===== 5. 头部 ===== */
.site-header{
  position:sticky;top:0;z-index:80;
  background:var(--paper);
  border-bottom:1px solid var(--rule);
  box-shadow:var(--shadow-1);
}
.header-inner{
  max-width:var(--w);margin-inline:auto;
  padding-inline:var(--gutter);
  min-height:74px;
  display:flex;align-items:center;
  gap:clamp(10px,2vw,26px);
}
.brand-link{display:flex;align-items:center;gap:12px;min-width:0}
.brand-mark{
  flex:none;width:38px;height:38px;border-radius:2px;
  display:grid;place-items:center;
  background:var(--lake);color:var(--paper);
  font-family:var(--font-display);font-weight:900;font-size:18px;line-height:1;
  box-shadow:inset 0 -2px 0 rgba(14,74,87,.55);
}
.brand-text{display:flex;flex-direction:column;line-height:1.2;min-width:0}
.brand-name{
  font-family:var(--font-display);font-weight:700;
  font-size:clamp(15px,1.2vw,17px);letter-spacing:.02em;
}
.brand-tagline{
  margin-top:3px;
  font-family:var(--font-mono);font-size:11px;letter-spacing:.04em;
  color:var(--note);
}

/* 导航 */
.site-nav{margin-left:auto}
.nav-list{display:flex;align-items:center;gap:clamp(2px,1vw,18px)}
.nav-link{
  display:inline-flex;align-items:center;gap:6px;
  padding:11px 2px;
  font-size:14px;color:var(--ink);
  border-bottom:2px solid transparent;
  transition:color var(--dur) var(--ease),border-color var(--dur) var(--ease);
}
.nav-num{
  font-family:var(--font-mono);font-size:10px;font-weight:500;
  letter-spacing:.08em;color:var(--ochre);
  transition:color var(--dur) var(--ease),background var(--dur) var(--ease);
}
.nav-link:hover{color:var(--lake)}
.nav-link:hover .nav-num{color:var(--lake-deep)}
.nav-link[aria-current="page"]{
  color:var(--lake-deep);font-weight:700;
  border-bottom-color:var(--ochre);
}
.nav-link[aria-current="page"] .nav-num{
  background:var(--ochre);color:var(--paper);
  padding:0 4px;border-radius:2px;
}

.header-cta{
  flex:none;display:inline-flex;align-items:center;
  padding:9px 16px;border-radius:2px;
  font-size:13.5px;font-weight:700;white-space:nowrap;
  color:var(--lake-deep);border:1px solid var(--lake);
  transition:background var(--dur) var(--ease),color var(--dur) var(--ease);
}
.header-cta:hover{background:var(--lake);color:var(--paper)}

.nav-toggle{
  display:none;align-items:center;gap:9px;
  padding:9px 12px;border-radius:2px;
  border:1px solid var(--rule);background:var(--paper);
  color:var(--lake-deep);
}
.nav-toggle-label{
  font-family:var(--font-mono);font-size:11px;letter-spacing:.14em;
}
.nav-toggle-bars{position:relative;display:block;width:18px;height:10px}
.nav-toggle-bars > span{
  position:absolute;left:0;width:100%;height:2px;border-radius:1px;
  background:currentColor;
  transition:transform var(--dur) var(--ease),opacity 160ms linear;
}
.nav-toggle-bars > span:nth-child(1){top:0}
.nav-toggle-bars > span:nth-child(2){top:4px}
.nav-toggle-bars > span:nth-child(3){top:8px}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars > span:nth-child(1){transform:translateY(4px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars > span:nth-child(2){opacity:0}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars > span:nth-child(3){transform:translateY(-4px) rotate(-45deg)}

/* 阅读进度 */
.read-progress{
  position:absolute;left:0;right:0;bottom:-1px;
  height:2px;overflow:hidden;pointer-events:none;
}
.read-progress-bar{
  display:block;height:100%;width:0;
  background:linear-gradient(90deg,var(--lake) 0%,var(--ochre) 100%);
  transition:width 120ms linear;
}

/* ===== 6. 按钮 ===== */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:12px 22px;border-radius:2px;
  font-size:15px;font-weight:700;line-height:1.35;
  border:1px solid var(--rule);background:var(--paper);color:var(--ink);
  transition:background var(--dur) var(--ease),color var(--dur) var(--ease),
             border-color var(--dur) var(--ease),transform var(--dur) var(--ease);
}
.btn:hover{transform:translateY(-1px)}
.btn--primary{background:var(--lake);border-color:var(--lake);color:var(--paper)}
.btn--primary:hover{background:var(--lake-deep);border-color:var(--lake-deep)}
.btn--ochre{background:var(--ochre);border-color:var(--ochre);color:var(--paper)}
.btn--ochre:hover{background:#8D4A21;border-color:#8D4A21}
.btn--ghost{background:transparent;border-color:var(--lake);color:var(--lake)}
.btn--ghost:hover{background:var(--lake-pale)}
.btn-row{display:flex;flex-wrap:wrap;gap:12px;align-items:center}

/* ===== 7. 面包屑 ===== */
.crumbs{
  background:linear-gradient(180deg,var(--paper-2),var(--paper));
  border-bottom:1px solid var(--rule);
}
.crumbs-list{
  display:flex;flex-wrap:wrap;align-items:center;gap:8px;
  max-width:var(--w);margin-inline:auto;
  padding:16px var(--gutter);
  font-family:var(--font-mono);font-size:12.5px;letter-spacing:.04em;
  color:var(--note);
}
.crumbs-item{display:inline-flex;align-items:center;gap:8px}
.crumbs-item[aria-current="page"]{color:var(--ink);font-weight:500}
.crumbs-link{border-bottom:1px solid transparent;transition:color 160ms var(--ease),border-color 160ms var(--ease)}
.crumbs-link:hover{color:var(--lake-deep);border-bottom-color:var(--ochre)}
.crumbs-sep{color:var(--rule)}

/* ===== 8. 容器与节奏 ===== */
.wrap{width:100%;max-width:var(--w);margin-inline:auto;padding-inline:var(--gutter)}
.section{padding-block:clamp(52px,8vw,96px);scroll-margin-top:92px}
.section--tight{padding-block:clamp(32px,5vw,64px)}
.section--tint{background:var(--lake-pale)}
.section--paper{background:var(--paper-2)}

/* ===== 9. 标题组 ===== */
.sec-head{
  display:grid;grid-template-columns:auto minmax(0,1fr);
  column-gap:clamp(14px,2vw,26px);row-gap:10px;align-items:start;
  margin-bottom:clamp(22px,3.6vw,44px);
}
.sec-num{
  grid-row:1 / span 2;
  font-family:var(--font-mono);font-weight:500;
  font-size:clamp(26px,3.4vw,44px);line-height:.95;
  letter-spacing:-.02em;color:var(--ochre);
  padding-top:2px;
}
.sec-title{
  align-self:center;
  font-family:var(--font-display);font-weight:700;
  font-size:clamp(22px,2.4vw,32px);line-height:1.22;letter-spacing:-.01em;
}
.sec-lead{
  grid-column:2;
  font-size:clamp(15px,1vw,17px);line-height:1.8;
  color:var(--note);max-width:60ch;
}

/* ===== 10. 布局网格 ===== */
.grid{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));gap:clamp(16px,2.4vw,32px)}
.span-4{grid-column:span 4}
.span-6{grid-column:span 6}
.span-8{grid-column:span 8}
.span-12{grid-column:span 12}
.layout{
  display:grid;grid-template-columns:minmax(150px,220px) minmax(0,1fr);
  gap:clamp(24px,4vw,56px);align-items:start;
}
.layout--with-note{grid-template-columns:minmax(140px,190px) minmax(0,1fr) minmax(170px,240px)}
.layout-axis{position:sticky;top:100px}
.layout-main{min-width:0}
.layout-note{font-size:13.5px;line-height:1.75;color:var(--note)}

/* ===== 11. 序号轴 ===== */
.axis-list{border-left:1px solid var(--rule);display:grid;gap:1px}
.axis-link{
  position:relative;display:flex;align-items:baseline;gap:9px;
  padding:9px 4px 9px 14px;
  font-size:14px;color:var(--note);
  transition:color 160ms var(--ease),background 160ms var(--ease);
}
.axis-link::before{
  content:"";position:absolute;left:-1px;top:7px;bottom:7px;width:1px;
  background:transparent;transform:scaleY(.35);transform-origin:top;
  transition:background 160ms var(--ease),transform 220ms var(--ease);
}
.axis-link:hover{color:var(--lake-deep)}
.axis-link[aria-current="true"]{
  color:var(--ink);font-weight:700;
  background:linear-gradient(90deg,rgba(22,105,122,.10),rgba(22,105,122,0) 78%);
}
.axis-link[aria-current="true"]::before{background:var(--ochre);transform:scaleY(1)}
.axis-num{
  flex:none;font-family:var(--font-mono);font-size:11px;
  letter-spacing:.08em;color:var(--ochre);
}

/* ===== 12. 边注与标签 ===== */
.note{position:relative;padding-left:15px;font-size:13.5px;line-height:1.72;color:var(--note)}
.note::before{
  content:"";position:absolute;left:0;top:.62em;
  width:10px;height:1px;background:var(--ochre);
  transform:rotate(-32deg);transform-origin:left center;
}
.note-text{display:inline}
.tag{
  display:inline-flex;align-items:center;gap:5px;white-space:nowrap;
  padding:3px 9px;border-radius:2px;
  font-family:var(--font-mono);font-size:11px;letter-spacing:.08em;line-height:1.7;
  border:1px solid var(--rule);background:var(--paper);color:var(--note);
}
.tag--new{background:var(--flame);border-color:var(--flame);color:#fff}
.tag--stable{background:var(--turq);border-color:var(--turq);color:#fff}
.tag--fix{background:var(--lake-pale);border-color:#BBD6DC;color:var(--lake-deep)}

/* ===== 13. 卡片 ===== */
.card{
  background:var(--paper);border:1px solid var(--rule);border-radius:3px;
  box-shadow:var(--shadow-1);
  padding:clamp(18px,2.2vw,28px);
}
.card-head{
  display:flex;flex-wrap:wrap;align-items:baseline;gap:10px;
  font-family:var(--font-display);font-weight:700;font-size:18px;line-height:1.35;
}
.card-body{margin-top:10px;font-size:14.5px;line-height:1.8;color:var(--note)}
.card--ochre{background:#FBF0E8;border-color:#E3C8B4}

/* ===== 14. 媒体容器 ===== */
.media{
  position:relative;overflow:hidden;
  border:1px solid var(--rule);border-radius:3px;
  background:var(--paper-2);
}
.media > img,
.media > picture > img{
  width:100%;height:100%;object-fit:cover;
  filter:saturate(.88) contrast(1.03);
}
.media--band{aspect-ratio:4 / 1}
.media--photo{aspect-ratio:3 / 2}
.media--square{aspect-ratio:1 / 1}
.media-caption{
  margin-top:10px;padding-left:12px;
  border-left:2px solid var(--ochre-pale);
  font-size:13px;line-height:1.65;color:var(--note);
}

/* ===== 15. 标签页 ===== */
.tab-list{
  display:flex;flex-wrap:wrap;gap:6px;
  border-bottom:1px solid var(--rule);
  margin-bottom:clamp(18px,2.4vw,28px);
}
.tab{
  position:relative;margin-bottom:-1px;
  padding:10px 16px;border-radius:3px 3px 0 0;
  border:1px solid transparent;border-bottom:0;
  font-size:14px;font-weight:700;color:var(--note);
  transition:color 160ms var(--ease),background 160ms var(--ease),border-color 160ms var(--ease);
}
.tab:hover{color:var(--lake-deep);background:var(--lake-pale)}
.tab[aria-selected="true"]{
  color:var(--lake-deep);background:var(--paper);
  border-color:var(--rule);border-bottom:1px solid var(--paper);
  box-shadow:inset 0 2px 0 var(--ochre);
}
.tab-panel{padding-top:2px}
.tab-panel[hidden]{display:none}

/* ===== 16. 可折叠步骤 ===== */
.step{
  border:1px solid var(--rule);border-radius:3px;
  background:var(--paper);box-shadow:var(--shadow-1);
}
.step + .step{margin-top:10px}
.step > summary{
  display:flex;align-items:baseline;gap:12px;
  padding:14px 18px;cursor:pointer;
  font-family:var(--font-display);font-weight:700;font-size:16px;line-height:1.5;
  transition:color 160ms var(--ease);
}
.step > summary::-webkit-details-marker{display:none}
.step > summary::after{
  content:"＋";margin-left:auto;
  font-family:var(--font-mono);font-weight:400;font-size:15px;color:var(--ochre);
}
.step[open] > summary{color:var(--lake-deep)}
.step[open] > summary::after{content:"−"}
.step-num{
  flex:none;font-family:var(--font-mono);font-size:12px;
  font-weight:500;letter-spacing:.08em;color:var(--ochre);
}
.step-body{padding:0 18px 18px;font-size:15.5px;line-height:1.85}

/* ===== 17. 显现 ===== */
[data-reveal]{
  opacity:0;transform:translateY(10px);
  transition:opacity 320ms var(--ease),transform 320ms var(--ease);
}
[data-reveal].is-visible{opacity:1;transform:none}

/* ===== 18. 页脚 ===== */
.site-footer{
  position:relative;
  background:var(--lake-deep);
  color:#E9F1F2;
  border-top:3px solid var(--ochre);
  margin-top:clamp(48px,7vw,96px);
}
.site-footer::before{
  content:"";display:block;height:4px;
  background:linear-gradient(90deg,
    var(--lake) 0 20%,var(--turq) 20% 33%,var(--ochre) 33% 61%,
    var(--flame) 61% 74%,var(--ochre-pale) 74% 100%);
}
.footer-inner{
  max-width:var(--w);margin-inline:auto;
  padding:clamp(38px,6vw,70px) var(--gutter) 30px;
}
.footer-top{
  display:grid;grid-template-columns:minmax(230px,1fr) 2fr;
  gap:clamp(28px,5vw,68px);
  padding-bottom:clamp(26px,4vw,46px);
  border-bottom:1px solid rgba(233,241,242,.18);
}
.footer-brand-name{
  font-family:var(--font-display);font-weight:900;
  font-size:clamp(21px,2.4vw,30px);line-height:1.2;letter-spacing:-.01em;
  color:#fff;
}
.footer-brand-note{
  margin-top:12px;max-width:34ch;
  font-size:14px;line-height:1.75;color:rgba(233,241,242,.72);
}
.footer-cta{
  display:inline-flex;align-items:center;gap:8px;
  margin-top:18px;padding-bottom:3px;
  font-size:14px;font-weight:700;color:var(--paper);
  border-bottom:1px solid var(--ochre);
  transition:color 160ms var(--ease),border-color 160ms var(--ease);
}
.footer-cta:hover{color:#fff;border-bottom-color:var(--flame)}
.footer-cols{
  display:grid;grid-template-columns:repeat(3,minmax(0,1fr));
  gap:clamp(18px,3vw,40px);
}
.footer-col{min-width:0}
.footer-col-title{
  margin-bottom:14px;
  font-family:var(--font-mono);font-size:11.5px;font-weight:500;
  letter-spacing:.16em;color:var(--ochre-pale);
}
.footer-links{display:grid;gap:9px}
.footer-link{
  display:inline-block;
  font-size:14px;color:rgba(233,241,242,.82);
  border-bottom:1px solid transparent;
  transition:color 160ms var(--ease),border-color 160ms var(--ease);
}
.footer-link:hover{color:#fff;border-bottom-color:var(--ochre)}
.footer-meta{
  display:grid;grid-template-columns:1.15fr 1fr;
  gap:clamp(22px,4vw,56px);
  padding-top:clamp(22px,3.4vw,38px);
}
.footer-contact{display:grid;gap:7px}
.footer-contact-line{
  display:flex;flex-wrap:wrap;gap:10px;
  font-size:13.5px;line-height:1.7;color:rgba(233,241,242,.78);
}
.footer-contact-label{
  flex:none;min-width:42px;
  font-family:var(--font-mono);font-size:11px;letter-spacing:.12em;
  color:var(--ochre-pale);padding-top:2px;
}
.footer-contact-value{min-width:0}
.footer-legal{display:grid;gap:6px;align-content:start}
.footer-legal-line{
  font-size:12.5px;line-height:1.7;color:rgba(233,241,242,.58);
}

/* ===== 19. 响应式 ===== */
@media (max-width:1020px){
  .site-nav{
    position:absolute;left:0;right:0;top:100%;
    background:var(--paper);
    border-bottom:1px solid var(--rule);
    box-shadow:var(--shadow-2);
    max-height:0;opacity:0;visibility:hidden;overflow:hidden;
    transition:max-height 260ms var(--ease),opacity 180ms linear,visibility 0s linear 220ms;
  }
  .site-nav[data-open]{
    max-height:76vh;overflow-y:auto;opacity:1;visibility:visible;
    transition:max-height 300ms var(--ease),opacity 200ms linear,visibility 0s;
  }
  .nav-list{flex-direction:column;align-items:stretch;gap:0;padding:6px 0}
  .nav-item + .nav-item{border-top:1px solid var(--rule)}
  .nav-link{
    padding:14px var(--gutter);
    font-size:16px;
    border-bottom:0;
    border-left:3px solid transparent;
  }
  .nav-link[aria-current="page"]{
    border-left-color:var(--ochre);
    border-bottom-color:transparent;
    background:var(--lake-pale);
  }
  .nav-toggle{display:inline-flex}
  .header-cta{margin-left:auto}
  body.nav-open{overflow:hidden}
  .layout--with-note{grid-template-columns:minmax(140px,190px) minmax(0,1fr)}
  .layout-note{grid-column:1 / -1}
}
@media (max-width:900px){
  .span-4,.span-6,.span-8{grid-column:span 12}
  .layout,.layout--with-note{grid-template-columns:minmax(0,1fr)}
  .layout-axis{position:static}
  .footer-top{grid-template-columns:1fr}
  .footer-meta{grid-template-columns:1fr}
}
@media (max-width:720px){
  .header-cta{display:none}
  .nav-toggle{margin-left:auto}
  .header-inner{min-height:66px}
  .brand-mark{width:34px;height:34px;font-size:16px}
  .media--band{aspect-ratio:3 / 1}
  .sec-head{grid-template-columns:minmax(0,1fr)}
  .sec-num{grid-row:auto;padding-top:0}
  .sec-lead{grid-column:1}
}
@media (max-width:640px){
  .footer-cols{grid-template-columns:repeat(2,minmax(0,1fr))}
  .brand-tagline{display:none}
}
@media (max-width:420px){
  .footer-cols{grid-template-columns:minmax(0,1fr)}
  .footer-inner{padding-bottom:26px}
  .btn{width:100%}
  .btn-row{gap:10px}
}

/* ===== 20. 动效降级 ===== */
@media (prefers-reduced-motion: no-preference){
  html{scroll-behavior:smooth}
  .tab-panel{animation:panelIn 220ms var(--ease) both}
}
@keyframes panelIn{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}
@media (prefers-reduced-motion: reduce){
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
    scroll-behavior:auto !important;
  }
  [data-reveal]{opacity:1;transform:none}
  .btn:hover{transform:none}
}