/* ============================================================
   四季官网 · /assets/site.css
   共享外壳：重置 / 变量 / 头部侧轨导航 / 页脚 / 通用组件
   ============================================================ */

/* ---------- 1. 设计变量 ---------- */
:root{
  --paper:#F7F5F0;
  --card:#FFFDF9;
  --ink:#1E1E1C;
  --scale:#6E6E68;
  --line:#D8D4CB;
  --green-deep:#3F5A3A;
  --spring:#A8C97F;
  --summer:#E86A33;
  --autumn:#9C5A3C;
  --winter:#7B8FA1;

  --topbar-h:64px;
  --rail-w:236px;
  --gut:clamp(18px,4vw,56px);
  --gap:clamp(16px,2.2vw,32px);

  --font-display:"Archivo Narrow","Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,sans-serif;
  --font-body:"Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,sans-serif;
  --font-mono:"IBM Plex Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,"Noto Sans Mono CJK SC",monospace;

  --ease:cubic-bezier(.22,.61,.36,1);
  --dur:.32s;
}

/* ---------- 2. 重置与基础 ---------- */
*,*::before,*::after{box-sizing:border-box}
html{
  -webkit-text-size-adjust:100%;
  scroll-behavior:smooth;
  scroll-padding-top:calc(var(--topbar-h) + 20px);
}
body{
  margin:0;
  padding-top:var(--topbar-h);
  background-color:var(--paper);
  background-image:linear-gradient(to right,rgba(30,30,28,.045) 1px,transparent 1px);
  background-size:clamp(56px,7vw,104px) 100%;
  color:var(--ink);
  font-family:var(--font-body);
  font-size:16px;
  line-height:1.75;
  letter-spacing:.01em;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
main{display:block}
img,svg,video{max-width:100%;display:block}
a{color:inherit}
button,input,select,textarea{font:inherit;color:inherit}
h1,h2,h3,h4,h5{margin:0;font-family:var(--font-display);font-weight:600;line-height:1.14;letter-spacing:.02em}
p{margin:0}
ul,ol,dl,dd{margin:0;padding:0}
[hidden]{display:none !important}
::selection{background:var(--summer);color:#fff}
:focus-visible{outline:2px solid var(--summer);outline-offset:3px}

/* ---------- 3. 无障碍与工具类 ---------- */
.skip-link{
  position:fixed;top:8px;left:8px;z-index:200;
  transform:translateY(-180%);
  display:inline-block;
  padding:12px 18px;
  background:var(--ink);color:var(--paper);
  font-family:var(--font-mono);font-size:12px;letter-spacing:.14em;
  text-decoration:none;
  transition:transform .2s var(--ease);
}
.skip-link:focus{transform:translateY(0)}
.visually-hidden{
  position:absolute;width:1px;height:1px;margin:-1px;padding:0;
  overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0;
}

/* ---------- 4. 头部：顶栏 ---------- */
.site-header{position:relative;z-index:60}
.topbar{
  position:fixed;top:0;left:0;right:0;height:var(--topbar-h);z-index:70;
  display:flex;align-items:center;gap:clamp(14px,2vw,32px);
  padding-inline:var(--gut);
  background:rgba(247,245,240,.95);
  border-bottom:1px solid var(--line);
  -webkit-backdrop-filter:saturate(150%) blur(8px);
  backdrop-filter:saturate(150%) blur(8px);
}
@media (min-width:1024px){
  .topbar{padding-left:calc(var(--rail-w) + 28px)}
  .topbar::before{
    content:"";position:absolute;left:0;top:0;bottom:0;width:var(--rail-w);
    border-right:1px solid var(--line);
    background-image:repeating-linear-gradient(to right,var(--line) 0 1px,transparent 1px 12px);
    opacity:.85;pointer-events:none;
  }
}
.brand{display:inline-flex;align-items:baseline;gap:10px;flex:0 0 auto;text-decoration:none;color:var(--ink)}
.brand__mark{font-family:var(--font-display);font-size:24px;font-weight:800;letter-spacing:.3em;line-height:1}
.brand__sub{
  padding-left:10px;border-left:1px solid var(--line);
  font-family:var(--font-mono);font-size:10.5px;letter-spacing:.22em;
  color:var(--scale);white-space:nowrap;
}
.topbar__chapter{
  display:flex;align-items:baseline;gap:10px;margin-inline-end:auto;min-width:0;
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.18em;color:var(--scale);
}
.topbar__num{font-size:13px;font-weight:600;color:var(--summer);letter-spacing:.1em}
.topbar__label{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.topbar__actions{display:flex;align-items:center;gap:10px;flex:0 0 auto}
.meter{position:absolute;left:0;right:0;bottom:-1px;height:2px;pointer-events:none;background:transparent}
.meter__fill{
  display:block;height:100%;width:0;
  background:linear-gradient(90deg,var(--spring),var(--summer) 42%,var(--autumn) 72%,var(--winter));
  transition:width .12s linear;
}

/* ---------- 5. 头部：移动端开关 ---------- */
.nav-toggle{
  display:none;align-items:center;gap:8px;
  min-height:44px;padding:0 12px;
  border:1px solid var(--ink);background:transparent;color:var(--ink);
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.16em;
  cursor:pointer;transition:background-color .2s linear,color .2s linear;
}
.nav-toggle:hover{background:rgba(30,30,28,.06)}
.nav-toggle__bars{position:relative;width:16px;height:9px;flex:0 0 auto}
.nav-toggle__bars::before,
.nav-toggle__bars::after{
  content:"";position:absolute;left:0;width:100%;height:1px;background:currentColor;
  transition:transform var(--dur) var(--ease);
}
.nav-toggle__bars::before{top:0}
.nav-toggle__bars::after{bottom:0}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before{transform:translateY(4px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after{transform:translateY(-4px) rotate(-45deg)}
.nav-toggle__text{white-space:nowrap}

/* ---------- 6. 头部：侧边刻度轨道导航 ---------- */
.site-rail{
  position:fixed;top:var(--topbar-h);left:0;bottom:0;width:var(--rail-w);z-index:68;
  display:flex;flex-direction:column;gap:18px;
  padding:24px 16px 20px;
  background:var(--paper);
  border-right:1px solid var(--line);
  overflow-y:auto;overscroll-behavior:contain;
}
.rail__head{display:flex;align-items:center;gap:10px;padding-inline:12px}
.rail__title{font-family:var(--font-mono);font-size:10.5px;letter-spacing:.26em;color:var(--scale);white-space:nowrap}
.rail__ruler{
  flex:1 1 auto;height:7px;opacity:.5;
  background-image:repeating-linear-gradient(to right,var(--scale) 0 1px,transparent 1px 9px);
}
.site-nav{display:block}
.site-nav__list{list-style:none;display:grid;gap:2px}
.site-nav__item{min-width:0}
.site-nav__link{
  display:flex;align-items:baseline;gap:12px;
  min-height:44px;padding:11px 12px;
  border-left:2px solid transparent;
  text-decoration:none;color:var(--ink);
  transition:background-color .2s linear,border-color .2s linear,color .2s linear;
}
.site-nav__index{font-family:var(--font-mono);font-size:10.5px;letter-spacing:.14em;color:var(--scale);flex:0 0 auto}
.site-nav__label{font-family:var(--font-display);font-size:14.5px;font-weight:500;letter-spacing:.06em;line-height:1.35}
.site-nav__link:hover{background:rgba(123,143,161,.12);border-left-color:var(--winter)}
.site-nav__link[data-active="true"]{background:rgba(123,143,161,.18);border-left-color:var(--winter)}
.site-nav__link[aria-current="page"]{
  background:rgba(232,106,51,.08);
  border-left-color:var(--summer);
}
.site-nav__link[aria-current="page"] .site-nav__index{color:var(--summer);font-weight:600}
.site-nav__link[aria-current="page"] .site-nav__label{font-weight:800}
.rail__seasons{margin-inline:12px}
.rail__foot{margin-top:auto;padding:14px 12px 0;border-top:1px solid var(--line)}
.rail__note{font-family:var(--font-mono);font-size:11px;letter-spacing:.1em;color:var(--scale);line-height:1.9}

.rail-scrim{
  position:fixed;inset:var(--topbar-h) 0 0 0;z-index:66;
  background:rgba(30,30,28,.4);
  opacity:0;visibility:hidden;
  transition:opacity var(--dur) linear,visibility var(--dur) linear;
}
html[data-nav-open] .rail-scrim{opacity:1;visibility:visible}
@media (min-width:1024px){
  .rail-scrim{display:none}
  body{padding-left:var(--rail-w)}
}

/* ---------- 7. 头部：返回顶部 ---------- */
.to-top{
  position:fixed;right:clamp(14px,2.4vw,32px);bottom:clamp(14px,2.4vw,32px);z-index:72;
  display:inline-flex;align-items:center;gap:8px;
  min-height:44px;padding:0 16px;
  border:1px solid var(--ink);background:var(--ink);color:var(--paper);
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.16em;
  cursor:pointer;
  transition:background-color .2s linear,border-color .2s linear,color .2s linear;
}
.to-top::before{
  content:"";width:0;height:0;
  border-left:4px solid transparent;border-right:4px solid transparent;
  border-bottom:6px solid currentColor;
}
.to-top:hover{background:var(--summer);border-color:var(--summer);color:#fff}

/* ---------- 8. 移动端：抽屉状态 ---------- */
@media (max-width:1023px){
  .nav-toggle{display:inline-flex}
  .site-rail{
    width:min(86vw,340px);
    transform:translateX(-102%);
    transition:transform var(--dur) var(--ease);
    box-shadow:0 24px 60px rgba(30,30,28,0);
    will-change:transform;
  }
  .site-rail[data-open]{
    transform:translateX(0);
    box-shadow:0 24px 60px rgba(30,30,28,.2);
  }
  html[data-nav-open]{overflow:hidden}
}
@media (max-width:760px){
  .topbar__cta{display:none}
}
@media (max-width:640px){
  .topbar__label{display:none}
  .brand__sub{display:none}
}

/* ---------- 9. 页脚 ---------- */
.site-footer{
  position:relative;
  margin-top:clamp(48px,8vw,120px);
  background:var(--green-deep);
  color:var(--paper);
}
.footer__band{gap:0;height:5px;background:transparent}
.footer__band .season-band__seg{opacity:1;animation:none}
.footer__inner{
  width:100%;max-width:1440px;margin-inline:auto;
  padding:clamp(34px,5vw,68px) var(--gut) clamp(20px,3vw,36px);
  display:grid;gap:clamp(22px,3.2vw,48px);
  grid-template-columns:minmax(0,1.5fr) minmax(0,1fr) minmax(0,1.25fr) minmax(0,.95fr);
  background-image:linear-gradient(to right,rgba(247,245,240,.07) 1px,transparent 1px);
  background-size:clamp(56px,7vw,104px) 100%;
}
.footer__col{min-width:0}
.footer__col--brand{display:block}
.footer__logo{
  display:inline-block;
  font-family:var(--font-display);font-size:30px;font-weight:800;letter-spacing:.32em;
  color:var(--paper);text-decoration:none;
  transition:color .2s linear;
}
.footer__logo:hover{color:var(--spring)}
.footer__tagline{
  margin-top:14px;
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.13em;
  color:rgba(247,245,240,.74);line-height:1.9;
}
.footer__meta{margin-top:20px;display:grid;gap:8px}
.footer__meta-row{
  display:flex;gap:12px;
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.05em;
  color:rgba(247,245,240,.8);
}
.footer__meta-row dt{flex:0 0 68px;color:rgba(247,245,240,.56)}
.footer__meta-row dd{margin:0;min-width:0;overflow-wrap:anywhere}
.footer__title{
  display:flex;align-items:baseline;gap:10px;
  font-family:var(--font-display);font-size:13px;font-weight:600;
  letter-spacing:.2em;color:var(--paper);
}
.footer__idx{font-family:var(--font-mono);font-size:10.5px;letter-spacing:.16em;color:var(--spring)}
.footer__list{list-style:none;margin-top:16px;display:grid;gap:10px}
.footer__list--plain{gap:16px}
.footer__link{
  display:inline-block;min-height:32px;padding-bottom:2px;
  font-size:14px;line-height:1.6;color:rgba(247,245,240,.86);
  text-decoration:none;border-bottom:1px solid transparent;
  transition:color .2s linear,border-color .2s linear;
}
.footer__link:hover{color:var(--paper);border-bottom-color:var(--summer)}
.footer__node{display:grid;gap:3px}
.footer__node-city{
  font-family:var(--font-display);font-size:15px;font-weight:600;
  letter-spacing:.1em;color:var(--paper);
}
.footer__node-desc{font-size:12.5px;line-height:1.7;color:rgba(247,245,240,.66)}
.footer__base{
  width:100%;max-width:1440px;margin-inline:auto;
  padding:16px var(--gut) clamp(18px,2.6vw,30px);
  border-top:1px solid rgba(247,245,240,.22);
  display:flex;flex-wrap:wrap;gap:10px 24px;justify-content:space-between;
  font-family:var(--font-mono);font-size:11px;letter-spacing:.1em;
  color:rgba(247,245,240,.64);
}
.footer__base-item{margin:0}
@media (max-width:1000px){
  .footer__inner{grid-template-columns:minmax(0,1fr) minmax(0,1fr)}
}
@media (max-width:620px){
  .footer__inner{grid-template-columns:minmax(0,1fr)}
}

/* ---------- 10. 布局容器与章节 ---------- */
.wrap{width:100%;max-width:1440px;margin-inline:auto;padding-inline:var(--gut)}
.section{
  padding-block:clamp(44px,6.5vw,96px);
  border-top:1px solid var(--line);
}
.section--flush{border-top:0;padding-top:clamp(28px,4vw,56px)}
.section__head{display:grid;gap:10px;margin-bottom:clamp(22px,3vw,40px)}
.eyebrow{
  display:inline-flex;align-items:center;gap:10px;
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.26em;
  text-transform:uppercase;color:var(--scale);
}
.eyebrow::before{content:"";width:26px;height:1px;background:var(--summer);flex:0 0 auto}
.section__title{font-size:clamp(28px,4.4vw,54px);font-weight:200;letter-spacing:-.01em}
.section__title strong{font-weight:800}
.lede{max-width:62ch;font-size:clamp(15px,1.1vw,17.5px);line-height:1.85;color:var(--scale)}
.rule{height:1px;border:0;margin:0;background:var(--line)}

/* ---------- 11. 栅格 ---------- */
.grid{display:grid;gap:var(--gap)}
.grid--asym{grid-template-columns:minmax(0,7fr) minmax(0,5fr)}
.grid--asym-rev{grid-template-columns:minmax(0,5fr) minmax(0,7fr)}
.grid--5-4-3{grid-template-columns:minmax(0,5fr) minmax(0,4fr) minmax(0,3fr)}
.grid--cards{grid-template-columns:repeat(auto-fill,minmax(min(100%,260px),1fr))}
@media (max-width:1000px){
  .grid--asym,.grid--asym-rev,.grid--5-4-3{grid-template-columns:minmax(0,1fr)}
}

/* ---------- 12. 按钮 ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  min-height:44px;padding:0 18px;
  border:1px solid var(--ink);background:transparent;color:var(--ink);
  font-family:var(--font-mono);font-size:12.5px;letter-spacing:.08em;
  text-decoration:none;cursor:pointer;
  transition:background-color .2s linear,color .2s linear,border-color .2s linear;
}
.btn--accent{border-color:var(--summer);color:var(--summer)}
.btn--accent:hover{background:var(--summer);border-color:var(--summer);color:#fff}
.btn--solid{background:var(--ink);border-color:var(--ink);color:var(--paper)}
.btn--solid:hover{background:var(--summer);border-color:var(--summer);color:#fff}
.btn--ghost{border-color:var(--line);color:var(--scale)}
.btn--ghost:hover{border-color:var(--ink);color:var(--ink)}
.btn--line{background:transparent;border-color:var(--scale)}

/* ---------- 13. 卡片体系 ---------- */
.card{
  position:relative;min-width:0;
  background:var(--card);
  border:1px solid var(--line);
  padding:clamp(18px,2vw,28px);
}
.card__index{font-family:var(--font-mono);font-size:11px;letter-spacing:.2em;color:var(--scale)}
.card__title{margin-top:8px;font-size:clamp(19px,1.5vw,24px);font-weight:600}
.card__text{margin-top:10px;font-size:14.5px;line-height:1.8;color:var(--scale)}
.card__foot{
  margin-top:18px;padding-top:12px;border-top:1px solid var(--line);
  display:flex;flex-wrap:wrap;justify-content:space-between;gap:8px 14px;
  font-family:var(--font-mono);font-size:12px;color:var(--scale);
}
.card__panel{margin-top:16px;padding-top:14px;border-top:1px dashed var(--line)}
.card__toggle{
  display:inline-flex;align-items:center;gap:8px;
  min-height:44px;margin-top:12px;padding:0 14px;
  border:1px solid var(--line);background:transparent;color:var(--scale);
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.12em;
  cursor:pointer;transition:border-color .2s linear,color .2s linear;
}
.card__toggle:hover{border-color:var(--ink);color:var(--ink)}
.card--overview{border-left:3px solid var(--winter)}
.card--overview[data-season="spring"]{border-left-color:var(--spring)}
.card--overview[data-season="summer"]{border-left-color:var(--summer)}
.card--overview[data-season="autumn"]{border-left-color:var(--autumn)}
.card--overview[data-season="winter"]{border-left-color:var(--winter)}
.card--spec{padding:0;overflow:hidden}
.card--spec .card__head{
  display:flex;flex-wrap:wrap;align-items:baseline;justify-content:space-between;gap:8px 16px;
  padding:16px clamp(14px,1.6vw,22px);
  border-bottom:1px solid var(--line);
}
.card__head{border-bottom:1px solid var(--line)}
.card--evidence{
  padding:4px 0 4px 20px;
  background:transparent;border:0;border-left:1px solid var(--autumn);
}
.card--evidence .card__title{font-family:var(--font-body);font-size:15px;font-weight:500;line-height:1.75;margin-top:0}
.card[data-expanded="false"] .card__panel{display:none}

/* ---------- 14. 参数表 ---------- */
.spec-table{
  width:100%;border-collapse:collapse;
  font-family:var(--font-mono);font-size:13px;line-height:1.7;
}
.spec-table caption{
  padding:14px clamp(14px,1.6vw,22px);text-align:left;
  font-family:var(--font-mono);font-size:11px;letter-spacing:.2em;
  color:var(--scale);text-transform:uppercase;
}
.spec-table th{
  background:rgba(156,90,60,.09);
  font-weight:600;letter-spacing:.12em;color:var(--ink);
  white-space:nowrap;
}
.spec-table th,.spec-table td{
  padding:12px clamp(12px,1.5vw,20px);
  border-bottom:1px solid var(--line);
  text-align:left;vertical-align:top;
}
.spec-table tbody tr:hover{background:rgba(232,106,51,.05)}
.spec-table tbody tr:last-child th,.spec-table tbody tr:last-child td{border-bottom:0}

/* ---------- 15. 时间轴 ---------- */
.timeline{
  position:relative;display:grid;gap:clamp(18px,2.4vw,32px);
  padding-left:clamp(18px,2.4vw,34px);
  border-left:1px solid var(--line);
}
.timeline__item{position:relative;min-width:0}
.timeline__item::before{
  content:"";position:absolute;left:-4px;top:9px;
  width:7px;height:7px;background:var(--summer);
}
.timeline__year{font-family:var(--font-mono);font-size:13px;letter-spacing:.16em;color:var(--autumn)}
.timeline__title{margin-top:4px;font-size:clamp(17px,1.4vw,21px);font-weight:600}
.timeline__text{margin-top:6px;font-size:14.5px;color:var(--scale)}

/* ---------- 16. 四季标签与色带 ---------- */
.season{
  --season:var(--winter);
  --season-bg:rgba(123,143,161,.14);
  display:inline-flex;align-items:center;gap:8px;
  padding:5px 10px;
  border:1px solid var(--season);background:var(--season-bg);
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.18em;color:var(--ink);
}
.season--spring{--season:var(--spring);--season-bg:rgba(168,201,127,.2)}
.season--summer{--season:var(--summer);--season-bg:rgba(232,106,51,.12)}
.season--autumn{--season:var(--autumn);--season-bg:rgba(156,90,60,.12)}
.season--winter{--season:var(--winter);--season-bg:rgba(123,143,161,.14)}
.season-band{display:grid;grid-template-columns:repeat(4,1fr);gap:4px;height:3px}
.season-band__seg{
  display:block;height:100%;
  animation:seasonDrift 8s var(--ease) infinite alternate;
}
.season-band__seg--spring{background:var(--spring)}
.season-band__seg--summer{background:var(--summer);animation-delay:.6s}
.season-band__seg--autumn{background:var(--autumn);animation-delay:1.2s}
.season-band__seg--winter{background:var(--winter);animation-delay:1.8s}
@keyframes seasonDrift{
  from{opacity:.35;transform:scaleY(.6)}
  to{opacity:1;transform:scaleY(1)}
}

/* ---------- 17. 图片容器 ---------- */
.figure{margin:0;background:var(--card);border:1px solid var(--line);overflow:hidden}
.figure__media{
  position:relative;overflow:hidden;
  background:linear-gradient(135deg,rgba(168,201,127,.28),rgba(123,143,161,.24) 45%,rgba(156,90,60,.2));
}
.figure__media > img,.figure__media > picture > img{width:100%;height:100%;object-fit:cover}
.figure--square .figure__media{aspect-ratio:1/1}
.figure--portrait .figure__media{aspect-ratio:3/4}
.figure--strip .figure__media{aspect-ratio:2/5}
.figure__caption{
  display:flex;flex-wrap:wrap;justify-content:space-between;gap:6px 14px;
  padding:10px 14px;border-top:1px solid var(--line);
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.04em;color:var(--scale);
}

/* ---------- 18. 面包屑 ---------- */
.breadcrumb{
  padding-block:16px;
  font-family:var(--font-mono);font-size:11.5px;letter-spacing:.12em;color:var(--scale);
}
.breadcrumb__list{list-style:none;display:flex;flex-wrap:wrap;align-items:center;gap:8px}
.breadcrumb__link{text-decoration:none;border-bottom:1px solid transparent;transition:color .2s linear,border-color .2s linear}
.breadcrumb__link:hover{color:var(--ink);border-bottom-color:var(--summer)}
.breadcrumb__sep{color:var(--line)}
.breadcrumb [aria-current="page"]{color:var(--ink)}

/* ---------- 19. 滚动显现 ---------- */
[data-reveal]{
  opacity:0;transform:translateY(12px);
  transition:opacity var(--dur) ease-out,transform var(--dur) ease-out;
}
[data-reveal].is-visible{opacity:1;transform:translateY(0)}

/* ---------- 20. 降低动效偏好 ---------- */
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
  }
  [data-reveal]{opacity:1;transform:none}
  .meter__fill{transition:none}
}