/* ============================================================
   sideline-william.com.cn — /assets/site.css
   共享外壳与基础组件
   ============================================================ */

/* ---------- 1. 变量 ---------- */
:root{
  --ink:#0A2621;
  --ink-deep:#121517;
  --ink-mid:#14392F;
  --surface:#1E4A44;
  --cyan:#2BF2D4;
  --cyan-soft:#8FF7E6;
  --orange:#FF6A1F;
  --orange-soft:#FFB489;
  --paper:#F7F4EC;
  --silver:#B9C6CC;

  --font-heading:"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans CJK SC","Source Han Sans SC","WenQuanYi Micro Hei",sans-serif;
  --font-body:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans CJK SC",sans-serif;
  --font-num:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,"Liberation Mono","Courier New",monospace;

  --fs-display:clamp(38px,6.2vw,64px);
  --fs-h1:clamp(30px,4.4vw,44px);
  --fs-h2:clamp(23px,2.8vw,28px);
  --fs-h3:clamp(18px,2vw,20px);
  --fs-body:clamp(16px,1.15vw,17px);
  --fs-note:14px;

  --num-xl:clamp(52px,9vw,96px);
  --num-lg:clamp(34px,5vw,56px);
  --num-md:clamp(24px,3.2vw,32px);

  --radius-lg:28px;
  --radius-md:18px;
  --radius-sm:12px;
  --radius-pill:999px;

  --gutter:clamp(18px,4vw,40px);
  --maxw:1240px;
  --ease:cubic-bezier(.2,.7,.3,1);
}

/* ---------- 2. Reset ---------- */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;scroll-padding-top:118px}
body,h1,h2,h3,h4,h5,p,ul,ol,dl,dd,dt,figure,blockquote{margin:0}
ul,ol{padding:0;list-style:none}
img,svg,picture,video{display:block;max-width:100%;height:auto}
button,input,select,textarea{font:inherit;color:inherit}
button{background:none;border:0;cursor:pointer}
a{color:var(--cyan);text-decoration:none;transition:color .2s ease}
a:hover{color:var(--cyan-soft)}
:focus-visible{outline:2px solid var(--cyan);outline-offset:3px;border-radius:4px}

/* ---------- 3. 中文排版基底 ---------- */
body{
  min-height:100vh;
  background:
    radial-gradient(1100px 620px at 10% -10%,rgba(43,242,212,.10),transparent 62%),
    radial-gradient(900px 560px at 98% 6%,rgba(255,106,31,.08),transparent 60%),
    var(--ink);
  color:var(--paper);
  font-family:var(--font-body);
  font-size:var(--fs-body);
  line-height:1.7;
  letter-spacing:.01em;
  overflow-x:hidden;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
h1,h2,h3,h4,h5{font-family:var(--font-heading);font-weight:800;letter-spacing:-.02em;line-height:1.16}
h1{font-size:var(--fs-h1)}
h2{font-size:var(--fs-h2)}
h3{font-size:var(--fs-h3)}
p{max-width:74ch}
strong{font-weight:800;color:var(--paper)}
mark{background:none;color:var(--paper);font-weight:800;box-shadow:inset 0 -.34em 0 rgba(43,242,212,.42)}

.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}

.divider{height:1px;border:0;background:linear-gradient(90deg,rgba(43,242,212,.36),rgba(185,198,204,.10) 45%,transparent)}

/* ---------- 4. 布局基础 ---------- */
.container{
  width:100%;
  max-width:var(--maxw);
  margin-inline:auto;
  padding-inline:var(--gutter);
}
#main-content{
  padding-top:clamp(84px,9vw,108px);
  min-height:60vh;
}
.section{padding-block:clamp(46px,7vw,88px)}
.section--tight{padding-block:clamp(28px,4vw,52px)}
.section__head{
  display:flex;
  flex-wrap:wrap;
  align-items:flex-end;
  justify-content:space-between;
  gap:18px;
  margin-bottom:clamp(24px,3vw,42px);
}
.grid{display:grid;gap:clamp(18px,2.4vw,30px)}
.grid--2{grid-template-columns:repeat(2,minmax(0,1fr))}
.grid--3{grid-template-columns:repeat(3,minmax(0,1fr))}
@media (min-width:901px){
  .grid--offset > *:nth-child(even){margin-top:clamp(20px,3.4vw,48px)}
}

/* ---------- 5. 通用文字组件 ---------- */
.eyebrow{
  display:inline-flex;
  align-items:center;
  gap:10px;
  font-family:var(--font-num);
  font-size:13px;
  font-weight:600;
  letter-spacing:.18em;
  text-transform:uppercase;
  color:var(--cyan);
}
.eyebrow::before{content:"";width:26px;height:2px;border-radius:2px;background:linear-gradient(90deg,var(--cyan),var(--orange))}

.lede{font-size:clamp(16.5px,1.55vw,20px);line-height:1.78;color:var(--silver);max-width:62ch}

.chapter{display:flex;align-items:baseline;gap:clamp(12px,1.6vw,20px);flex-wrap:wrap}
.chapter__num{
  font-family:var(--font-num);
  font-size:clamp(30px,4.2vw,54px);
  font-weight:700;
  line-height:1;
  letter-spacing:-.03em;
  color:var(--cyan);
  opacity:.42;
}
.chapter__title{font-size:var(--fs-h1);letter-spacing:-.025em}

/* ---------- 6. 按钮 ---------- */
.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:8px;
  padding:11px 20px;
  border-radius:var(--radius-pill);
  border:1px solid transparent;
  font-size:15px;
  font-weight:700;
  line-height:1;
  letter-spacing:.01em;
  text-decoration:none;
  cursor:pointer;
  white-space:nowrap;
  transition:background .2s ease,color .2s ease,border-color .2s ease,transform .2s var(--ease);
}
.btn:hover{transform:translateY(-1px)}
.btn:active{transform:translateY(0)}
.btn--accent{background:var(--orange);color:#20100A}
.btn--accent:hover{background:var(--orange-soft);color:#20100A}
.btn--ghost{background:rgba(43,242,212,.08);color:var(--cyan);border-color:rgba(43,242,212,.34)}
.btn--ghost:hover{background:rgba(43,242,212,.18);color:var(--cyan-soft)}
.btn--sm{padding:8px 15px;font-size:14px}

/* ---------- 7. 胶囊标签 / 卡片 / 数字条带 ---------- */
.pill{
  display:inline-flex;
  align-items:center;
  gap:8px;
  padding:7px 15px;
  border-radius:var(--radius-pill);
  background:rgba(43,242,212,.10);
  border:1px solid rgba(43,242,212,.26);
  color:var(--cyan);
  font-size:14px;
  font-weight:600;
  line-height:1.3;
}
.pill--orange{background:rgba(255,106,31,.12);border-color:rgba(255,106,31,.32);color:var(--orange-soft)}

.card{
  background:var(--ink-mid);
  border:1px solid rgba(43,242,212,.12);
  border-radius:var(--radius-lg);
  padding:clamp(20px,2.6vw,30px);
  transition:transform .25s var(--ease),border-color .25s ease,box-shadow .25s ease;
}
.card:hover{
  transform:translateY(-4px);
  border-color:rgba(43,242,212,.45);
  box-shadow:0 26px 54px -32px rgba(43,242,212,.55);
}
.card__title{font-size:var(--fs-h3);margin-bottom:8px}
.card__body{font-size:15.5px;color:var(--silver);line-height:1.72}

.stat{display:flex;flex-direction:column;gap:6px}
.stat__num{
  font-family:var(--font-num);
  font-size:var(--num-lg);
  font-weight:700;
  line-height:1;
  letter-spacing:-.03em;
  color:var(--orange);
}
.stat__unit{font-family:var(--font-num);font-size:.42em;color:var(--silver);margin-left:.35em;letter-spacing:0}
.stat__label{font-size:var(--fs-note);letter-spacing:.06em;color:var(--silver)}

.bar-strip{
  display:flex;
  flex-wrap:wrap;
  background:var(--ink-deep);
  border:1px solid rgba(185,198,204,.14);
  border-radius:var(--radius-lg);
  overflow:hidden;
}
.bar-strip__item{
  flex:1 1 190px;
  padding:16px 22px;
  border-right:1px solid rgba(185,198,204,.12);
  min-width:0;
}
.bar-strip__item:last-child{border-right:0}

/* ---------- 8. 面包屑 ---------- */
.breadcrumbs{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:8px;
  padding-top:20px;
  font-size:var(--fs-note);
  color:var(--silver);
}
.breadcrumbs__item{display:flex;align-items:center;gap:8px}
.breadcrumbs__item + .breadcrumbs__item::before{
  content:"/";
  font-family:var(--font-num);
  color:rgba(185,198,204,.45);
}
.breadcrumbs__link{color:var(--silver)}
.breadcrumbs__link:hover{color:var(--cyan)}
.breadcrumbs [aria-current="page"]{color:var(--paper);font-weight:600}

/* ---------- 9. 章节目录 ---------- */
.index-list{display:grid;gap:2px;margin:0;padding:0;list-style:none}
.index-list__link{
  display:flex;
  align-items:baseline;
  gap:12px;
  padding:10px 14px;
  border-radius:14px;
  border-left:3px solid transparent;
  color:var(--silver);
  font-size:15px;
  font-weight:600;
  transition:background .2s ease,color .2s ease,border-color .2s ease;
}
.index-list__link:hover{color:var(--paper);background:rgba(43,242,212,.08)}
.index-list__link[aria-current="true"]{
  color:var(--cyan);
  background:rgba(43,242,212,.10);
  border-left-color:var(--cyan);
}

/* ---------- 10. 图片容器 ---------- */
.media-frame{
  position:relative;
  display:block;
  width:100%;
  aspect-ratio:16/10;
  overflow:hidden;
  border-radius:var(--radius-lg);
  border:1px solid rgba(43,242,212,.14);
  background:linear-gradient(150deg,var(--ink-mid) 0%,#0D2F28 55%,var(--ink-deep) 100%);
}
.media-frame::after{
  content:"";
  position:absolute;
  inset:0;
  z-index:1;
  pointer-events:none;
  background:
    radial-gradient(120% 90% at 14% 0%,rgba(43,242,212,.18),transparent 60%),
    radial-gradient(95% 85% at 100% 100%,rgba(255,106,31,.15),transparent 66%);
}
.media-frame img{width:100%;height:100%;object-fit:cover}
.media-frame--wide{aspect-ratio:21/9}
.media-frame--square{aspect-ratio:1/1}
.media-frame--tall{aspect-ratio:3/4}
.media-frame__caption{
  position:absolute;
  z-index:2;
  left:16px;
  bottom:14px;
  padding:6px 13px;
  border-radius:var(--radius-pill);
  background:rgba(18,21,23,.72);
  color:var(--paper);
  font-size:13px;
  line-height:1.4;
  backdrop-filter:blur(6px);
}

/* ---------- 11. 跳转链接 ---------- */
.skip-link{
  position:absolute;
  top:-120px;
  left:50%;
  transform:translateX(-50%);
  z-index:120;
  padding:11px 20px;
  border-radius:0 0 14px 14px;
  background:var(--cyan);
  color:#062019;
  font-weight:700;
  font-size:15px;
  transition:top .2s var(--ease);
}
.skip-link:focus{top:0;color:#062019}

/* ---------- 12. 头部 ---------- */
.site-header{
  position:fixed;
  inset:0 0 auto 0;
  z-index:60;
  padding:clamp(10px,1.6vw,18px) var(--gutter);
  transition:padding .2s var(--ease);
}
.site-header.is-compact{padding-top:8px;padding-bottom:8px}

.scroll-progress{
  position:fixed;
  top:0;
  left:0;
  right:0;
  height:3px;
  z-index:90;
  background:rgba(43,242,212,.10);
  pointer-events:none;
}
.scroll-progress__bar{
  display:block;
  width:0;
  height:100%;
  background:linear-gradient(90deg,var(--cyan),var(--orange));
  transition:width .12s linear;
}

.header-island{
  position:relative;
  display:flex;
  align-items:center;
  gap:clamp(10px,1.8vw,26px);
  width:100%;
  max-width:var(--maxw);
  margin-inline:auto;
  padding:10px 12px 10px 18px;
  border-radius:var(--radius-pill);
  background:rgba(20,57,47,.80);
  border:1px solid rgba(43,242,212,.16);
  box-shadow:0 20px 44px -28px rgba(0,0,0,.92);
  backdrop-filter:blur(14px);
  transition:padding .2s var(--ease),background .2s ease,border-color .2s ease;
}
.site-header.is-compact .header-island{
  padding:6px 8px 6px 16px;
  background:rgba(18,21,23,.92);
  border-color:rgba(43,242,212,.24);
}

/* 品牌 */
.brand{
  display:flex;
  align-items:center;
  gap:12px;
  flex:0 0 auto;
  color:var(--paper);
  text-decoration:none;
}
.brand:hover{color:var(--paper)}
.brand__mark{
  position:relative;
  flex:0 0 auto;
  width:34px;
  height:34px;
  border-radius:12px;
  background:linear-gradient(118deg,var(--cyan) 0%,var(--cyan) 42%,var(--orange) 42%,var(--orange) 100%);
  box-shadow:inset 0 0 0 1px rgba(255,255,255,.16),0 8px 20px -10px rgba(43,242,212,.8);
}
.brand__mark::after{
  content:"";
  position:absolute;
  inset:auto 7px 7px auto;
  width:8px;
  height:8px;
  border-radius:50%;
  background:var(--ink-deep);
  opacity:.72;
}
.brand__text{display:flex;flex-direction:column;line-height:1.15}
.brand__name{font-family:var(--font-heading);font-weight:800;font-size:17px;letter-spacing:-.02em}
.brand__tagline{
  display:block;
  max-height:20px;
  overflow:hidden;
  font-size:12px;
  letter-spacing:.06em;
  color:var(--silver);
  transition:max-height .22s var(--ease),opacity .22s ease;
}
.site-header.is-compact .brand__tagline{max-height:0;opacity:0}

/* 胶囊导航 */
.nav-capsule{
  flex:1 1 auto;
  min-width:0;
  display:flex;
  justify-content:center;
}
.nav-capsule__list{display:flex;align-items:center;gap:2px}
.nav-capsule__link{
  display:block;
  padding:9px 14px;
  border-radius:var(--radius-pill);
  color:var(--silver);
  font-size:15px;
  font-weight:600;
  white-space:nowrap;
  transition:background .2s ease,color .2s ease;
}
.nav-capsule__link:hover{background:rgba(43,242,212,.10);color:var(--paper)}
.nav-capsule__link[aria-current="page"]{
  background:var(--cyan);
  color:var(--ink-deep);
  font-weight:800;
}

/* 工具区 */
.header-tools{display:flex;align-items:center;gap:10px;flex:0 0 auto}

/* 汉堡按钮 */
.nav-toggle{
  display:none;
  align-items:center;
  justify-content:center;
  width:44px;
  height:44px;
  border-radius:var(--radius-pill);
  border:1px solid rgba(43,242,212,.34);
  background:rgba(43,242,212,.08);
  color:var(--cyan);
  transition:background .2s ease,border-color .2s ease;
}
.nav-toggle:hover{background:rgba(43,242,212,.18)}
.nav-toggle__bars{display:flex;flex-direction:column;justify-content:center;gap:4px;width:18px}
.nav-toggle__bar{
  display:block;
  height:2px;
  border-radius:2px;
  background:currentColor;
  transition:transform .2s var(--ease),opacity .2s ease;
}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(1){transform:translateY(6px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(2){opacity:0}
.nav-toggle[aria-expanded="true"] .nav-toggle__bar:nth-child(3){transform:translateY(-6px) rotate(-45deg)}

/* ---------- 13. 页脚 ---------- */
.site-footer{
  position:relative;
  margin-top:clamp(64px,9vw,120px);
  background:var(--ink-deep);
  border-top:1px solid rgba(43,242,212,.16);
  overflow:hidden;
}
.site-footer::before{
  content:"";
  position:absolute;
  inset:0 0 auto 0;
  height:2px;
  background:linear-gradient(90deg,transparent,var(--cyan) 28%,var(--orange) 72%,transparent);
  opacity:.72;
}
.footer-inner{
  display:grid;
  grid-template-columns:1.15fr 1.7fr 1.15fr;
  gap:clamp(26px,4vw,56px);
  width:100%;
  max-width:var(--maxw);
  margin-inline:auto;
  padding:clamp(44px,6vw,74px) var(--gutter) clamp(32px,4vw,50px);
}
.footer-rail{display:flex;flex-direction:column;gap:12px}
.footer-brand{
  display:flex;
  align-items:center;
  gap:12px;
  color:var(--paper);
  font-family:var(--font-heading);
  font-size:20px;
  font-weight:800;
  letter-spacing:-.02em;
}
.footer-brand:hover{color:var(--paper)}
.footer-brand__tag{font-size:14px;color:var(--silver);letter-spacing:.05em}
.footer-signature{
  font-size:13.5px;
  line-height:1.7;
  color:rgba(185,198,204,.72);
  max-width:30ch;
}
.footer-map{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:clamp(20px,3vw,40px)}
.footer-map__title{
  font-family:var(--font-num);
  font-size:13px;
  font-weight:600;
  letter-spacing:.16em;
  text-transform:uppercase;
  color:var(--cyan);
  margin-bottom:16px;
}
.footer-map__list{display:grid;gap:10px}
.footer-map__link{
  display:inline-block;
  color:var(--silver);
  font-size:15px;
  font-weight:600;
  transition:color .2s ease,transform .2s var(--ease);
}
.footer-map__link:hover{color:var(--cyan);transform:translateX(3px)}
.footer-contact__list{display:grid;gap:12px}
.footer-contact__row{display:grid;grid-template-columns:72px minmax(0,1fr);gap:12px;align-items:baseline}
.footer-contact__label{font-size:13px;color:rgba(185,198,204,.66);letter-spacing:.04em}
.footer-contact__value{
  font-size:14px;
  line-height:1.6;
  color:var(--paper);
  word-break:break-word;
}
.footer-contact__row:nth-child(2) .footer-contact__value{font-family:var(--font-num);letter-spacing:.02em;color:var(--orange-soft)}

.footer-legal{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:12px 26px;
  width:100%;
  max-width:var(--maxw);
  margin-inline:auto;
  padding:20px var(--gutter) 36px;
  border-top:1px solid rgba(185,198,204,.16);
  font-size:13.5px;
  color:var(--silver);
}
.footer-legal__copy{margin:0}
.footer-legal__links{display:flex;flex-wrap:wrap;gap:8px 20px}
.footer-legal__links a{color:var(--silver)}
.footer-legal__links a:hover{color:var(--cyan)}
.footer-legal__icp{font-family:var(--font-num);letter-spacing:.02em;color:rgba(185,198,204,.72)}

/* ---------- 14. 返回顶部 ---------- */
.to-top{
  position:fixed;
  right:clamp(14px,3vw,28px);
  bottom:clamp(14px,3vw,28px);
  z-index:70;
  display:grid;
  place-items:center;
  width:48px;
  height:48px;
  border-radius:var(--radius-pill);
  border:1px solid rgba(43,242,212,.42);
  background:rgba(18,21,23,.90);
  color:var(--cyan);
  opacity:0;
  visibility:hidden;
  transform:translateY(12px);
  backdrop-filter:blur(10px);
  transition:opacity .22s ease,visibility .22s ease,transform .22s var(--ease),background .2s ease;
}
.to-top[data-visible="true"]{opacity:1;visibility:visible;transform:none}
.to-top:hover{background:rgba(43,242,212,.16)}
.to-top__icon{
  display:block;
  width:11px;
  height:11px;
  border-left:2px solid currentColor;
  border-top:2px solid currentColor;
  transform:rotate(45deg) translate(1px,1px);
  border-radius:1px;
}

/* ---------- 15. 显现动效 ---------- */
.js-reveal [data-reveal]{
  opacity:0;
  transform:translateY(22px);
  transition:opacity .7s var(--ease),transform .7s var(--ease);
}
.js-reveal [data-reveal].is-revealed{opacity:1;transform:none}

/* ---------- 16. 断点 ---------- */
@media (max-width:1180px){
  .nav-capsule__link{padding:8px 10px;font-size:14.5px}
  .btn{padding:10px 16px;font-size:14.5px}
}

@media (max-width:1023px){
  .nav-toggle{display:inline-flex}
  .btn--wide-hide{display:none}

  .nav-capsule{
    position:fixed;
    top:76px;
    left:var(--gutter);
    right:var(--gutter);
    z-index:80;
    display:block;
    padding:14px;
    border-radius:24px;
    background:rgba(18,21,23,.97);
    border:1px solid rgba(43,242,212,.22);
    box-shadow:0 30px 60px -30px rgba(0,0,0,.95);
    max-height:calc(100vh - 116px);
    overflow-y:auto;
    opacity:0;
    visibility:hidden;
    transform:translateY(-10px);
    pointer-events:none;
    transition:opacity .2s ease,transform .2s var(--ease),visibility .2s ease;
  }
  .nav-capsule[data-open="true"]{
    opacity:1;
    visibility:visible;
    transform:none;
    pointer-events:auto;
  }
  .nav-capsule__list{flex-direction:column;align-items:stretch;gap:4px}
  .nav-capsule__link{
    padding:13px 16px;
    border-radius:16px;
    font-size:16px;
    border-left:3px solid transparent;
  }
  .nav-capsule__link[aria-current="page"]{
    background:rgba(43,242,212,.14);
    color:var(--cyan);
    border-left-color:var(--cyan);
  }
}

@media (max-width:900px){
  .grid--2,.grid--3{grid-template-columns:minmax(0,1fr)}
  .footer-inner{grid-template-columns:minmax(0,1fr);gap:34px}
  .footer-map{grid-template-columns:repeat(2,minmax(0,1fr))}
  .footer-legal{justify-content:flex-start}
}

@media (max-width:560px){
  .brand__tagline{display:none}
  .brand__mark{width:30px;height:30px;border-radius:10px}
  .brand__name{font-size:16px}
  .header-tools .btn--accent{padding:9px 14px;font-size:13.5px}
  .nav-toggle{width:40px;height:40px}
  .nav-capsule{top:70px}
  .footer-map{grid-template-columns:minmax(0,1fr)}
  .footer-contact__row{grid-template-columns:minmax(0,1fr);gap:2px}
  .bar-strip__item{border-right:0;border-bottom:1px solid rgba(185,198,204,.12)}
  .bar-strip__item:last-child{border-bottom:0}
  .to-top{width:44px;height:44px}
}

/* ---------- 17. 降低动效 ---------- */
@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
    scroll-behavior:auto !important;
  }
  .js-reveal [data-reveal]{opacity:1;transform:none}
  .card:hover,.footer-map__link:hover,.btn:hover{transform:none}
}