/* ============================================================
   LIANZAO V24 — base layer: reset, type, frame, navigation,
   footer, controls, reveal, shared primitives.
   ============================================================ */

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;text-size-adjust:100%;scroll-behavior:smooth}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
body{
  margin:0;
  background:var(--paper);
  background-image:
    radial-gradient(86% 52% at 72% -6%, var(--stage-hi) 0%, transparent 62%),
    radial-gradient(120% 70% at 8% 4%, var(--stage-lo) 0%, transparent 58%);
  background-repeat:no-repeat;
  background-attachment:fixed;
  color:var(--ink);
  font-family:var(--font-ui);
  font-size:var(--step-0);
  line-height:1.72;
  font-feature-settings:"kern" 1,"liga" 1;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
  overflow-x:hidden;
}
html[data-theme-changing] *{transition:none!important}
img,svg,canvas{display:block;max-width:100%}
img{height:auto}
a{color:inherit;text-decoration:none}
button{font:inherit;color:inherit;background:none;border:0;cursor:pointer}
ul,ol{margin:0;padding:0;list-style:none}
h1,h2,h3,h4,h5,h6{margin:0;font-family:var(--font-display);font-weight:500;line-height:1.24;letter-spacing:.005em;text-wrap:balance}
h1,h2{font-weight:500}
h3,h4,h5,h6{font-family:var(--font-sans);font-weight:600;line-height:1.3;letter-spacing:-.005em}
p{margin:0}
:focus-visible{outline:2px solid var(--accent);outline-offset:3px;border-radius:2px}
::selection{background:var(--accent);color:#fff}

.skip-link{
  position:fixed;left:16px;top:-100px;z-index:120;
  padding:10px 18px;background:var(--ink);color:var(--ink-inverse);font-size:13px;
  transition:top .2s var(--ease);
}
.skip-link:focus{top:12px}

/* ---------- shell & rules ---------- */
.shell{width:100%;max-width:var(--shell);margin-inline:auto;padding-inline:var(--gutter)}
.hairline{height:1px;background:var(--line);border:0;margin:0}
.rule-x{height:1px;background:var(--line);border:0;margin:clamp(32px,4vw,60px) 0}

/* ---------- type primitives ---------- */
.meta{
  display:inline-flex;align-items:center;gap:10px;
  font-family:var(--font-mono);font-size:var(--t-meta);
  letter-spacing:.22em;text-transform:uppercase;color:var(--ink-3);
  line-height:1.4;
}
.meta .dot{width:5px;height:5px;border-radius:50%;background:var(--signal);flex:none}
.meta .bar{width:26px;height:1px;background:var(--line-strong);flex:none}
.display{font-family:var(--font-display);font-size:var(--t-display);line-height:1.16;letter-spacing:.01em;font-weight:500}
.display em{font-style:normal;color:var(--ink-2)}
.lede{font-size:var(--t-lead);line-height:1.65;color:var(--ink-2);max-width:var(--measure-lead)}
.body{color:var(--ink-2);max-width:var(--measure-body)}
.body p+p{margin-top:1.05em}
.quiet{color:var(--ink-3);font-size:var(--t-small)}

/* ---------- controls ---------- */
.hero-act{display:flex;align-items:center;gap:var(--s2);margin-top:clamp(4px,1.2vh,12px)}
.btn{
  display:inline-flex;align-items:center;gap:12px;
  min-height:52px;padding:0 28px;
  border:1px solid var(--ink);border-radius:999px;
  background:var(--ink);color:var(--ink-inverse);
  font-family:var(--font-sans);font-size:var(--t-body);letter-spacing:.08em;
  transition:background .3s var(--ease),color .3s var(--ease),border-color .3s var(--ease),transform .3s var(--ease);
}
.btn:hover{background:var(--accent);border-color:var(--accent);color:#fff;transform:translateY(-1px)}
.btn .arw{font-size:var(--t-body);line-height:1;transform:translateY(-1px)}
.btn-quiet{
  display:inline-flex;align-items:center;gap:10px;min-height:48px;
  font-size:var(--t-body);color:var(--ink-2);border-bottom:1px solid var(--line-strong);
  padding-bottom:4px;
  transition:color .24s var(--ease),border-color .24s var(--ease);
}
.btn-quiet:hover{color:var(--ink);border-color:var(--ink)}
.link-arrow{
  display:inline-flex;align-items:center;gap:11px;
  min-height:44px;padding:0 16px;
  border:1px solid var(--line-strong);
  font-size:13.5px;letter-spacing:.03em;color:var(--ink);
  transition:color .24s var(--ease),border-color .24s var(--ease),background .24s var(--ease);
}
.link-arrow span{
  width:22px;height:22px;display:grid;place-items:center;
  border-radius:50%;background:var(--ink);color:var(--paper);
  font-size:10.5px;line-height:1;
  transition:background .24s var(--ease),color .24s var(--ease);
}
.link-arrow:hover{color:var(--ink);border-color:var(--ink)}
.link-arrow:hover span{background:var(--accent);color:#fff}

/* inline mail address */
.mail-link{
  color:var(--accent);
  border-bottom:1px solid var(--line-strong);
  font-family:var(--font-mono);
  font-size:var(--t-small);
  padding-bottom:1px;
  white-space:nowrap;
  transition:border-color .24s var(--ease);
}
.mail-link:hover{border-color:var(--accent)}

/* ---------- header ---------- */
.site-header{
  position:sticky;top:0;z-index:60;
  height:var(--header-h);
  background:color-mix(in srgb,var(--paper) 88%,transparent);
  backdrop-filter:blur(14px) saturate(1.1);
  -webkit-backdrop-filter:blur(14px) saturate(1.1);
  border-bottom:1px solid var(--line);
}
.header-inner{
  height:100%;max-width:var(--shell);margin-inline:auto;padding-inline:var(--gutter);
  display:grid;grid-template-columns:auto 1fr auto;align-items:center;gap:clamp(18px,2.2vw,40px);
}
.brand{display:inline-flex;align-items:center;line-height:0}
.brand img{width:clamp(118px,10vw,146px);height:auto}
.brand .logo-dark{display:none}
html[data-theme="dark"] .brand .logo-light{display:none}
html[data-theme="dark"] .brand .logo-dark{display:block}

.primary-nav{display:flex;justify-content:center;gap:clamp(14px,2vw,34px)}
.primary-nav a{
  position:relative;padding:8px 0;font-size:13px;color:var(--ink-2);
  transition:color .24s var(--ease);white-space:nowrap;
}
.primary-nav a::after{
  content:"";position:absolute;left:0;right:0;bottom:0;height:1px;
  background:var(--accent);transform:scaleX(0);transform-origin:left;
  transition:transform .3s var(--ease);
}
.primary-nav a:hover{color:var(--ink)}
.primary-nav a:hover::after{transform:scaleX(1)}
.primary-nav a[aria-current="page"]{color:var(--ink);font-weight:600}
.primary-nav a[aria-current="page"]::after{transform:scaleX(1)}

.header-actions{display:flex;align-items:center;gap:6px}
.theme-toggle{
  width:44px;height:44px;display:grid;place-items:center;
  border:1px solid var(--line);border-radius:50%;
  transition:border-color .24s var(--ease),background .24s var(--ease);
}
.theme-toggle:hover{border-color:var(--line-strong);background:var(--paper-raised)}
.theme-icon{width:18px;height:18px;position:relative;display:block}
.theme-icon::before{
  content:"";position:absolute;inset:0;border-radius:50%;
  background:linear-gradient(90deg,var(--ink) 0 50%,transparent 50% 100%);
  border:1.5px solid var(--ink);
}
.theme-toggle .t-label{
  position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);
}
.menu-toggle{
  display:none;width:44px;height:44px;border:1px solid var(--line);border-radius:50%;
  place-items:center;position:relative;
}
.menu-toggle i{position:absolute;left:13px;right:13px;height:1.5px;background:var(--ink);transition:transform .26s var(--ease),opacity .2s}
.menu-toggle i:first-child{top:19px}
.menu-toggle i:last-child{top:24px}
.menu-toggle[aria-expanded="true"] i:first-child{transform:translateY(2.5px) rotate(45deg)}
.menu-toggle[aria-expanded="true"] i:last-child{transform:translateY(-2.5px) rotate(-45deg)}

/* ---------- scroll progress ---------- */
.read-progress{position:fixed;left:0;top:0;height:1.5px;width:0;background:var(--signal);z-index:70;pointer-events:none;opacity:.9}

/* ---------- hero frame ---------- */
.scene-frame{position:relative;overflow:hidden;isolation:isolate}

.scene-canvas{position:absolute;inset:0;width:100%;height:100%;pointer-events:none}
/* studio-rendered still: cover the frame so its own ground becomes the frame ground —
   no rectangular seam, and the object reads larger */
.scene-art{
  position:absolute;inset:0;width:100%;height:100%;
  object-fit:cover;object-position:50% 50%;
  pointer-events:none;user-select:none;
  transform:scale(1.02);
  animation:art-drift 34s cubic-bezier(.4,0,.6,1) infinite alternate;
  transition:transform 1.3s var(--ease), opacity .5s var(--ease);
}
/* a slow studio sweep: the plate is lit once every cycle, never flashed */
.scene-frame::after{
  content:"";position:absolute;inset:-25%;pointer-events:none;
  background:linear-gradient(112deg,transparent 40%,rgba(255,255,255,.42) 49%,rgba(255,255,255,.62) 51%,transparent 60%);
  mix-blend-mode:soft-light;
  animation:art-sweep 18s linear infinite;
}
html[data-theme="dark"] .scene-frame::after{
  background:linear-gradient(112deg,transparent 40%,rgba(180,214,255,.22) 49%,rgba(210,232,255,.34) 51%,transparent 60%);
}
@keyframes art-drift{
  from{transform:scale(1.015) translate3d(0,0,0)}
  to{transform:scale(1.065) translate3d(-1.1%,-1.5%,0)}
}
@keyframes art-sweep{
  0%{transform:translate3d(-32%,0,0)}
  55%{transform:translate3d(32%,0,0)}
  100%{transform:translate3d(32%,0,0)}
}
.scene-frame:hover .scene-art{animation-play-state:paused;transform:scale(1.055)}
@media (prefers-reduced-motion:reduce){
  .scene-art{animation:none;transform:none;transition:none}
  .scene-frame::after{animation:none;opacity:0}
  .scene-frame:hover .scene-art{transform:none}
}
@media (prefers-reduced-motion:reduce){
  .scene-art{transition:none}
  .scene-frame:hover .scene-art{transform:none}
}
.scene-glow{
  position:absolute;inset:0;pointer-events:none;
  background:
    radial-gradient(66% 58% at 50% 44%,color-mix(in srgb,var(--signal) 9%,transparent),transparent 74%),
    radial-gradient(90% 42% at 50% 100%,color-mix(in srgb,var(--brand) 6%,transparent),transparent 70%);
  opacity:.92;
}
.scene-caption{
  position:absolute;left:0;right:0;bottom:0;
  display:flex;justify-content:space-between;align-items:flex-end;gap:16px;
  padding:34px 2px 7px;border-bottom:1px solid var(--line);
  background:linear-gradient(to top,var(--paper) 26%,color-mix(in srgb,var(--paper) 74%,transparent) 64%,transparent);
  font-family:var(--font-mono);font-size:var(--t-meta);letter-spacing:.16em;text-transform:uppercase;color:var(--ink-3);
}
.scene-caption b{color:var(--ink);font-weight:500}
/* placeholder while a lost GL context is being restored */
.scene-hold{
  position:absolute;inset:0;pointer-events:none;
  background:
    radial-gradient(58% 52% at 50% 46%,color-mix(in srgb,var(--signal) 7%,transparent),transparent 72%),
    linear-gradient(to top,color-mix(in srgb,var(--paper-deep) 62%,transparent),transparent 46%);
  transition:opacity .4s var(--ease);
}

/* ---------- section header (12-col grammar, see DESIGN_SYSTEM §6) ---------- */
.sec-head{
  display:grid;grid-template-columns:repeat(12,minmax(0,1fr));
  column-gap:var(--col-gap);row-gap:var(--s3);align-items:end;
}
.sec-head > div:first-child{grid-column:1 / 7}
.sec-head > .aside{grid-column:8 / 13}
.sec-head h2{font-size:var(--t-h2);line-height:1.24;letter-spacing:.01em}
.sec-head h2 span{display:block;color:var(--ink-2)}
.sec-head .aside{padding-bottom:6px}
.sec-num{
  font-family:var(--font-mono);font-size:var(--t-meta);letter-spacing:.22em;color:var(--ink-3);
  padding-bottom:var(--s2);
}

/* ---------- reveal ---------- */
html.js .reveal{opacity:0;transform:translateY(26px);transition:opacity .62s cubic-bezier(.16,1,.3,1),transform .62s cubic-bezier(.16,1,.3,1)}
html.js .reveal.is-in{opacity:1;transform:none}
.reveal-d1{transition-delay:.08s}
.reveal-d2{transition-delay:.16s}
.reveal-d3{transition-delay:.24s}
@media (prefers-reduced-motion:reduce){
  html .reveal,html.js .reveal{opacity:1!important;transform:none!important;transition:none!important}
}

/* ---------- footer ---------- */
.site-footer{
  border-top:1px solid var(--line);
  margin-top:var(--section);
  padding:clamp(44px,6vw,80px) 0 28px;
}
.footer-grid{
  display:grid;grid-template-columns:1fr 1.1fr 1.32fr;gap:clamp(24px,3.6vw,64px);
}
.footer-brand img{width:clamp(130px,10vw,158px)}
.footer-brand p{margin-top:22px;color:var(--ink-2);font-size:var(--t-body);line-height:1.8}
.footer-nav{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:0 24px}
.footer-nav a{
  display:flex;align-items:center;justify-content:space-between;
  padding:12px 0;border-bottom:1px solid var(--line);font-size:var(--t-body);color:var(--ink-2);
  transition:color .22s var(--ease),padding .22s var(--ease);
}
.footer-nav a:hover{color:var(--ink);padding-left:4px}
.footer-nav .idx{font-family:var(--font-mono);font-size:var(--t-meta);color:var(--ink-3)}
.footer-note p{margin-top:20px;font-size:13px;line-height:1.85;color:var(--ink-3);max-width:none;text-wrap:pretty}
.footer-bottom{
  margin-top:clamp(36px,5vw,64px);padding-top:18px;border-top:1px solid var(--line);
  display:flex;justify-content:center;align-items:center;gap:clamp(28px,4.6vw,64px);flex-wrap:wrap;
  font-family:var(--font-mono);font-size:var(--t-meta);letter-spacing:.14em;text-transform:uppercase;color:var(--ink-3);
}
.footer-bottom a{color:var(--ink-2);display:inline-flex;align-items:center;min-height:44px;padding-inline:2px;margin-block:-12px}
.footer-bottom a:hover{color:var(--ink)}
.footer-mail{text-transform:none;letter-spacing:.02em;border-bottom:0}
.footer-note .link-arrow{display:inline-flex;margin-top:24px}

/* ---------- toast ---------- */
.toast{
  position:fixed;left:50%;bottom:32px;transform:translate(-50%,24px);
  padding:14px 22px;background:var(--ink);color:var(--ink-inverse);
  font-size:13px;border-radius:2px;opacity:0;pointer-events:none;z-index:80;
  transition:opacity .3s var(--ease),transform .3s var(--ease);
  max-width:min(92vw,560px);text-align:center;
}
.toast.show{opacity:1;transform:translate(-50%,0)}

/* ---------- responsive frame ---------- */
@media (max-width:1180px){
  .primary-nav{gap:16px}
  .primary-nav a{font-size:12px}
}
@media (max-width:1023px){
  :root{--header-h:68px}
  .primary-nav{
    position:fixed;left:0;right:0;top:var(--header-h);
    display:grid;grid-template-columns:1fr;
    background:var(--paper-raised);
    border-bottom:1px solid var(--line);
    padding:10px var(--gutter) 20px;
    gap:0;
    transform:translateY(-8px);opacity:0;pointer-events:none;visibility:hidden;
    transition:opacity .3s var(--ease),transform .3s var(--ease),visibility .3s;
    box-shadow:0 22px 40px -30px rgba(0,0,0,.5);
    z-index:65;
  }
  .primary-nav.open{opacity:1;transform:none;pointer-events:auto;visibility:visible}
  .primary-nav a{
    display:flex;align-items:center;justify-content:space-between;
    min-height:52px;border-bottom:1px solid var(--line);font-size:15px;color:var(--ink);
  }
  .primary-nav a::after{display:none}
  .primary-nav a[aria-current="page"]{color:var(--accent)}
  .menu-toggle{display:grid}
  .header-inner{grid-template-columns:1fr auto}
  .brand img{width:118px}
}
@media (max-width:820px){
  .sec-head{grid-template-columns:1fr;align-items:start;gap:24px}
  .sec-head > div:first-child,.sec-head > .aside{grid-column:1 / -1}
  .footer-grid{grid-template-columns:1fr;gap:40px}
  .footer-nav{gap:0 20px}
}
@media (max-width:680px){
  :root{--header-h:64px;--section:76px}
  body{font-size:15px;line-height:1.7}
  .display{font-size:clamp(36px,10.6vw,52px)}
  .sec-head h2{font-size:clamp(27px,7.4vw,36px)}
  .footer-grid{grid-template-columns:1fr}
  .footer-nav{grid-template-columns:repeat(2,minmax(0,1fr));grid-template-rows:repeat(3,auto)}
  .footer-nav a{padding:13px 0;font-size:var(--t-small)}
  .footer-brand p{font-size:13px}
  .toast{bottom:18px;font-size:var(--t-small)}
  .scene-caption{font-size:var(--t-meta);letter-spacing:.1em;flex-direction:column;align-items:flex-start;gap:4px;padding-bottom:8px}
  .scene-caption span{opacity:.85}
}

/* 回到顶部：右下角悬浮 */
.to-top{
  position:fixed;
  right:clamp(16px,2.4vw,32px);
  bottom:clamp(16px,2.4vw,32px);
  width:46px;height:46px;
  display:inline-flex;align-items:center;justify-content:center;
  padding:0;
  border:1px solid var(--line-strong);
  border-radius:50%;
  background:var(--paper-raised);
  color:var(--ink-2);
  cursor:pointer;
  opacity:0;transform:translateY(10px);pointer-events:none;
  transition:opacity .32s ease,transform .32s ease,background .24s ease,color .24s ease,border-color .24s ease;
  z-index:60;
  box-shadow:0 1px 3px rgba(12,18,22,.07);
}
.to-top.is-on{opacity:1;transform:none;pointer-events:auto;}
.to-top:hover{background:var(--ink);color:var(--paper);border-color:var(--ink);}
.to-top:focus-visible{outline:2px solid var(--accent);outline-offset:3px;}
@media (prefers-reduced-motion:reduce){.to-top{transition:none;}}
/* header logo：图形 + 联造（无英文），34 / 32px 高 */
.header-inner .brand img{height:34px;width:auto}
@media (max-width:680px){.header-inner .brand img{height:32px}}

/* footer logo：与 header 同一套资源、同一高度 */
.footer-brand .brand img{height:34px;width:auto}
@media (max-width:680px){.footer-brand .brand img{height:32px}}