:root{
  --ink-deep:#061F1A;
  --ink-graphite:#0D1211;
  --paper:#F2E8D5;
  --brown:#241A12;
  --cyan:#39F6D0;
  --orange:#FF5A2A;
  --yellow:#FFD166;
  --steel:#4D7C73;
  --mist:#F7FFF9;
  --line:rgba(57,246,208,.16);
  --line-soft:rgba(242,232,213,.12);
  --rail-w:248px;
  --bar-h:62px;
  --gutter:clamp(18px,4vw,56px);
  --font-cn:"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Source Han Sans SC","Noto Sans SC",system-ui,sans-serif;
  --font-mono:ui-monospace,"SFMono-Regular",Menlo,Consolas,"Liberation Mono",monospace;
}

*,*::before,*::after{box-sizing:border-box;}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;}
body{
  margin:0;
  min-height:100vh;
  font-family:var(--font-cn);
  font-size:clamp(15px,.35vw + 14px,17px);
  line-height:1.75;
  color:var(--mist);
  background-color:var(--ink-deep);
  background-image:
    radial-gradient(1200px 620px at 88% -12%,rgba(57,246,208,.10),transparent 70%),
    radial-gradient(900px 520px at -6% 104%,rgba(255,90,42,.08),transparent 70%),
    repeating-linear-gradient(to right,rgba(57,246,208,.05) 0 1px,transparent 1px 96px),
    repeating-linear-gradient(to bottom,rgba(57,246,208,.05) 0 1px,transparent 1px 96px);
  background-attachment:fixed;
  padding-top:var(--bar-h);
  padding-left:0;
}
h1,h2,h3,h4,p,figure,blockquote{margin:0;}
ul,ol{margin:0;padding:0;list-style:none;}
a{color:inherit;text-decoration:none;}
button{font:inherit;color:inherit;background:none;border:0;cursor:pointer;}
img{display:block;max-width:100%;height:auto;}
main{display:block;}
:focus-visible{outline:2px solid var(--cyan);outline-offset:3px;}

/* ---------- skip link ---------- */
.skip-link{
  position:fixed;
  top:8px;
  left:8px;
  z-index:200;
  padding:10px 16px;
  background:var(--cyan);
  color:var(--ink-deep);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.12em;
  transform:translateY(-240%);
  transition:transform .18s ease;
}
.skip-link:focus{transform:none;}

/* ---------- header / side rail ---------- */
.site-header{
  position:fixed;
  top:0;
  left:0;
  right:0;
  z-index:90;
  background:linear-gradient(180deg,rgba(6,31,26,.98),rgba(6,31,26,.92));
  border-bottom:1px solid var(--line);
}
.rail{
  display:flex;
  flex-direction:row;
  align-items:center;
  justify-content:space-between;
  gap:12px;
  min-height:var(--bar-h);
  padding:10px var(--gutter);
}
.brand{
  display:flex;
  flex-direction:row;
  flex-wrap:wrap;
  align-items:baseline;
  gap:4px 10px;
  color:var(--mist);
}
.brand__mark{
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.24em;
  text-transform:uppercase;
  color:var(--cyan);
}
.brand__name{
  font-size:19px;
  font-weight:900;
  letter-spacing:.07em;
  line-height:1.2;
}
.brand__tagline{display:none;}

.nav-toggle{
  display:inline-flex;
  align-items:center;
  gap:10px;
  padding:9px 12px;
  border:1px solid var(--line);
  color:var(--cyan);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.16em;
  text-transform:uppercase;
  transition:border-color .2s ease,color .2s ease,background-color .2s ease;
}
.nav-toggle:hover{border-color:var(--cyan);background:rgba(57,246,208,.08);}
.nav-toggle__bars{display:inline-flex;flex-direction:column;gap:3px;width:18px;}
.nav-toggle__bars span{display:block;height:2px;background:currentColor;transition:transform .2s ease,opacity .2s ease;}
.nav-toggle__text{display:inline-block;line-height:1;}
.site-header[data-open="true"] .nav-toggle__bars span:nth-child(1){transform:translateY(5px) rotate(45deg);}
.site-header[data-open="true"] .nav-toggle__bars span:nth-child(2){opacity:0;}
.site-header[data-open="true"] .nav-toggle__bars span:nth-child(3){transform:translateY(-5px) rotate(-45deg);}
.site-header[data-open="true"] .nav-toggle{border-color:var(--orange);color:var(--orange);}

.site-nav{
  position:fixed;
  top:var(--bar-h);
  left:0;
  right:0;
  z-index:85;
  display:flex;
  flex-direction:column;
  gap:16px;
  max-height:calc(100dvh - var(--bar-h));
  overflow-y:auto;
  padding:20px var(--gutter) 34px;
  background:linear-gradient(180deg,#071F1A,#0D1211);
  border-bottom:1px solid var(--line);
  box-shadow:0 26px 60px rgba(0,0,0,.55);
  opacity:0;
  visibility:hidden;
  pointer-events:none;
  transform:translateY(-12px);
  transition:opacity .22s ease,transform .22s ease,visibility .22s;
}
.site-header[data-open="true"] .site-nav{opacity:1;visibility:visible;pointer-events:auto;transform:none;}
.site-nav__label{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--steel);
}
.site-nav__list{display:flex;flex-direction:column;}
.site-nav__item{display:block;}
.site-nav__link{
  display:flex;
  align-items:center;
  gap:12px;
  padding:12px 10px;
  border-left:2px solid transparent;
  border-bottom:1px solid rgba(242,232,213,.08);
  color:rgba(247,255,249,.76);
  font-size:16px;
  letter-spacing:.03em;
  transition:color .2s ease,border-color .2s ease,background-color .2s ease;
}
.site-nav__link:hover{color:var(--mist);background:rgba(57,246,208,.07);}
.site-nav__link[aria-current="page"]{
  color:var(--cyan);
  border-left-color:var(--cyan);
  background:linear-gradient(90deg,rgba(57,246,208,.16),transparent);
}
.site-nav__index{
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  color:var(--steel);
}
.site-nav__link[aria-current="page"] .site-nav__index{color:var(--orange);}
.site-nav__text{display:inline-block;line-height:1.4;}

.rail__utility{display:flex;flex-direction:column;gap:6px;}
.rail__utility-title{
  font-family:var(--font-mono);
  font-size:10.5px;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--steel);
}
.rail__utility-list{display:flex;flex-wrap:wrap;gap:6px 16px;}
.rail__utility-link{
  display:inline-block;
  padding:3px 0;
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.08em;
  color:rgba(247,255,249,.66);
  border-bottom:1px dashed rgba(242,232,213,.22);
  transition:color .2s ease,border-color .2s ease;
}
.rail__utility-link:hover{color:var(--cyan);border-color:var(--cyan);}
.rail__cta{display:block;}

/* ---------- buttons ---------- */
.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:8px;
  padding:11px 18px;
  border:1px solid var(--cyan);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.14em;
  text-transform:uppercase;
  line-height:1.2;
  transition:background-color .2s ease,color .2s ease,border-color .2s ease;
}
.btn--primary{background:var(--cyan);color:var(--ink-deep);font-weight:700;}
.btn--primary:hover{background:var(--orange);border-color:var(--orange);color:var(--ink-deep);}
.btn--ghost{background:transparent;color:var(--cyan);}
.btn--ghost:hover{background:rgba(57,246,208,.12);}

/* ---------- footer ---------- */
.site-footer{
  position:relative;
  margin-top:clamp(48px,8vw,96px);
  background:linear-gradient(180deg,#0A1A16,#0D1211 55%,#061F1A);
  border-top:1px solid var(--line);
  color:rgba(247,255,249,.78);
}
.footer__stripe{height:4px;background:linear-gradient(90deg,var(--cyan) 0 22%,var(--yellow) 22% 28%,var(--orange) 28% 44%,rgba(77,124,115,.45) 44% 100%);}
.footer__grid{
  display:grid;
  grid-template-columns:1fr;
  gap:clamp(24px,3vw,40px);
  width:100%;
  max-width:1280px;
  margin-inline:auto;
  padding:clamp(34px,5vw,64px) var(--gutter) clamp(22px,3vw,40px);
}
.footer__brand{display:flex;flex-direction:column;gap:8px;}
.footer__mark{
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.26em;
  text-transform:uppercase;
  color:var(--cyan);
}
.footer__name{font-size:22px;font-weight:900;letter-spacing:.06em;color:var(--mist);}
.footer__summary{font-size:13.5px;line-height:1.7;color:rgba(247,255,249,.6);max-width:34ch;}
.footer__col{display:flex;flex-direction:column;gap:10px;}
.footer__col-title{
  font-family:var(--font-mono);
  font-size:10.5px;
  letter-spacing:.2em;
  text-transform:uppercase;
  color:var(--yellow);
  padding-bottom:6px;
  border-bottom:1px solid var(--line-soft);
}
.footer__links{display:flex;flex-direction:column;gap:7px;}
.footer__link{
  display:inline-block;
  font-size:13.5px;
  color:rgba(247,255,249,.74);
  border-bottom:1px solid transparent;
  transition:color .2s ease,border-color .2s ease;
}
.footer__link:hover{color:var(--cyan);border-color:rgba(57,246,208,.5);}
.footer__contact{display:flex;flex-direction:column;gap:8px;}
.footer__contact-line{display:flex;gap:8px;font-size:13px;line-height:1.6;}
.footer__contact-key{
  flex:0 0 auto;
  font-family:var(--font-mono);
  font-size:10.5px;
  letter-spacing:.14em;
  color:var(--steel);
  padding-top:2px;
}
.footer__contact-value{color:rgba(247,255,249,.82);word-break:break-word;}
.footer__note{font-size:12px;line-height:1.7;color:rgba(247,255,249,.48);max-width:38ch;}
.footer__col--contact{padding-top:2px;}
.footer__meta{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:8px 24px;
  width:100%;
  max-width:1280px;
  margin-inline:auto;
  padding:16px var(--gutter) 32px;
  border-top:1px solid var(--line-soft);
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.08em;
  color:var(--steel);
}
.footer__icp{color:rgba(247,255,249,.5);}
.footer__copy{color:rgba(247,255,249,.5);}

/* ---------- scroll utilities ---------- */
.scroll-meter{
  position:fixed;
  left:0;
  right:0;
  top:var(--bar-h);
  height:2px;
  z-index:95;
  background:rgba(247,255,249,.08);
  pointer-events:none;
}
.scroll-meter__bar{
  display:block;
  height:100%;
  width:100%;
  transform:scaleX(0);
  transform-origin:0 50%;
  background:linear-gradient(90deg,var(--cyan),var(--yellow),var(--orange));
}
.to-top{
  position:fixed;
  right:16px;
  bottom:16px;
  z-index:95;
  display:inline-flex;
  align-items:center;
  gap:8px;
  padding:10px 14px;
  background:rgba(13,18,17,.92);
  border:1px solid var(--line);
  color:var(--cyan);
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  text-transform:uppercase;
  opacity:0;
  visibility:hidden;
  transform:translateY(8px);
  transition:opacity .2s ease,transform .2s ease,visibility .2s ease,border-color .2s ease;
}
.to-top:hover{border-color:var(--cyan);}
.to-top[data-visible="true"]{opacity:1;visibility:visible;transform:none;}
.to-top__arrow{display:inline-block;line-height:1;}

/* ---------- shared layout ---------- */
.container{width:100%;max-width:1280px;margin-inline:auto;padding-inline:var(--gutter);}
.section{padding-block:clamp(38px,6vw,80px);}
.section__head{display:flex;flex-direction:column;gap:10px;margin-bottom:clamp(20px,3vw,36px);}
.section__title{font-size:clamp(24px,3vw,36px);font-weight:900;letter-spacing:.02em;line-height:1.28;}
.section__lead{font-size:16px;line-height:1.75;color:rgba(247,255,249,.72);max-width:62ch;}
.eyebrow{
  display:inline-flex;
  align-items:center;
  gap:10px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.22em;
  text-transform:uppercase;
  color:var(--cyan);
}
.eyebrow::before{content:"";width:26px;height:1px;background:var(--orange);}
.grid{display:grid;gap:clamp(16px,2.4vw,28px);}
.grid--2{grid-template-columns:1fr;}
.grid--3{grid-template-columns:1fr;}
.stack{display:flex;flex-direction:column;gap:clamp(12px,2vw,20px);}

/* ---------- breadcrumb ---------- */
.breadcrumb{padding-block:14px;border-bottom:1px solid var(--line-soft);}
.breadcrumb__list{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:8px;
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.1em;
  color:var(--steel);
}
.breadcrumb__item{display:inline-flex;align-items:center;}
.breadcrumb__item + .breadcrumb__item::before{content:"/";margin-right:8px;color:rgba(77,124,115,.8);}
.breadcrumb__link{color:rgba(247,255,249,.66);border-bottom:1px solid transparent;transition:color .2s ease,border-color .2s ease;}
.breadcrumb__link:hover{color:var(--cyan);border-color:rgba(57,246,208,.5);}
.breadcrumb__current{color:var(--mist);}

/* ---------- data tags ---------- */
.data-tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:3px 8px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.12em;
  text-transform:uppercase;
  color:var(--yellow);
  border:1px solid rgba(255,209,102,.4);
  background:rgba(255,209,102,.08);
}
.data-tag--live{color:var(--cyan);border-color:rgba(57,246,208,.45);background:rgba(57,246,208,.1);}
.data-tag--alert{color:var(--orange);border-color:rgba(255,90,42,.45);background:rgba(255,90,42,.1);}

/* ---------- prose ---------- */
.prose{max-width:68ch;color:rgba(247,255,249,.82);}
.prose h2,.prose h3{color:var(--mist);line-height:1.32;margin-top:1.6em;}
.prose h2{font-size:clamp(21px,2.4vw,28px);}
.prose h3{font-size:clamp(17px,1.8vw,21px);}
.prose p{margin-top:.9em;}
.prose ul{margin-top:.9em;display:grid;gap:.5em;}
.prose ul li{position:relative;padding-left:18px;}
.prose ul li::before{content:"▸";position:absolute;left:0;color:var(--cyan);font-family:var(--font-mono);}
.prose a{color:var(--cyan);border-bottom:1px solid rgba(57,246,208,.4);}
.prose--paper{
  background:var(--paper);
  color:var(--brown);
  max-width:74ch;
  padding:clamp(20px,4vw,48px);
  border:1px solid rgba(36,26,18,.14);
}
.prose--paper h2,.prose--paper h3{color:var(--brown);}
.prose--paper ul li::before{color:var(--orange);}
.prose--paper a{color:#8A2D0C;border-color:rgba(138,45,12,.4);}

/* ---------- media frame ---------- */
.media-frame{
  position:relative;
  display:block;
  aspect-ratio:16 / 9;
  overflow:hidden;
  border:1px solid var(--line);
  background:
    linear-gradient(135deg,rgba(57,246,208,.16),rgba(6,31,26,.92) 56%,rgba(255,90,42,.18)),
    repeating-linear-gradient(135deg,rgba(242,232,213,.06) 0 1px,transparent 1px 10px);
}
.media-frame img{width:100%;height:100%;object-fit:cover;}
.media-frame::after{
  content:attr(data-label);
  position:absolute;
  left:0;
  bottom:0;
  padding:4px 10px;
  font-family:var(--font-mono);
  font-size:11px;
  letter-spacing:.14em;
  color:var(--ink-deep);
  background:var(--cyan);
}
.media-frame__caption{
  margin-top:8px;
  font-family:var(--font-mono);
  font-size:11.5px;
  letter-spacing:.06em;
  color:var(--steel);
}
.media-frame--wide{aspect-ratio:21 / 9;}
.media-frame--tall{aspect-ratio:3 / 4;}

/* ---------- chapter nav (page stage hook) ---------- */
.chapter-nav{display:flex;flex-direction:column;gap:4px;}
.chapter-nav__link{
  display:block;
  padding:7px 10px;
  border-left:2px solid rgba(77,124,115,.5);
  font-family:var(--font-mono);
  font-size:12px;
  letter-spacing:.08em;
  color:rgba(247,255,249,.6);
  transition:color .2s ease,border-color .2s ease,background-color .2s ease;
}
.chapter-nav__link:hover{color:var(--mist);background:rgba(57,246,208,.07);}
.chapter-nav__link[aria-current="true"]{color:var(--cyan);border-left-color:var(--orange);background:rgba(57,246,208,.1);}

/* ---------- tablet ---------- */
@media (min-width:720px){
  .grid--2{grid-template-columns:repeat(2,1fr);}
  .grid--3{grid-template-columns:repeat(2,1fr);}
  .footer__grid{grid-template-columns:repeat(2,1fr);}
  .footer__brand{grid-column:1 / -1;}
  .footer__col--contact{grid-column:1 / -1;}
}

/* ---------- desktop rail ---------- */
@media (min-width:1024px){
  body{padding-top:0;padding-left:var(--rail-w);}
  .site-header{
    inset:0 auto 0 0;
    right:auto;
    bottom:0;
    width:var(--rail-w);
    display:flex;
    flex-direction:column;
    border-bottom:0;
    border-right:1px solid var(--line);
    background:linear-gradient(180deg,rgba(13,18,17,.96),rgba(6,31,26,.98));
    overflow-y:auto;
  }
  .rail{
    flex:1 1 auto;
    flex-direction:column;
    align-items:stretch;
    justify-content:flex-start;
    gap:0;
    min-height:100%;
    padding:26px 20px 24px;
  }
  .brand{
    flex-direction:column;
    align-items:flex-start;
    gap:5px;
    padding-bottom:18px;
    border-bottom:1px solid var(--line);
  }
  .brand__name{font-size:21px;}
  .brand__tagline{display:block;font-size:11.5px;line-height:1.55;color:var(--steel);max-width:24ch;}
  .nav-toggle{display:none;}
  .site-nav{
    position:static;
    display:flex;
    max-height:none;
    overflow:visible;
    opacity:1;
    visibility:visible;
    pointer-events:auto;
    transform:none;
    padding:0;
    margin-top:20px;
    background:none;
    border:0;
    box-shadow:none;
  }
  .site-nav__label{margin-bottom:8px;}
  .site-nav__link{
    gap:10px;
    padding:8px 10px;
    font-size:13.5px;
    border-bottom:0;
    border-left:2px solid transparent;
  }
  .site-nav__list{gap:2px;}
  .rail__utility{margin-top:24px;padding-top:16px;border-top:1px solid var(--line-soft);}
  .rail__utility-list{flex-direction:column;gap:6px;}
  .rail__cta{margin-top:auto;padding-top:24px;}
  .rail__cta .btn{width:100%;}
  .scroll-meter{left:var(--rail-w);top:0;}
  .to-top{right:24px;bottom:24px;}
  .footer__grid{grid-template-columns:1.6fr 1fr 1fr 1fr 1.35fr;}
  .footer__brand{grid-column:auto;}
  .footer__col--contact{grid-column:auto;}
  .grid--3{grid-template-columns:repeat(3,1fr);}
}

@media (min-width:1280px){
  .site-nav__link{font-size:14px;}
}

/* ---------- reduced motion ---------- */
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto;}
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
  }
}