/* ============ 0. RESET ============ */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;scroll-padding-top:120px}
body,h1,h2,h3,h4,p,ul,ol,li,figure,blockquote,dl,dd{margin:0;padding:0}
ul,ol{list-style:none}
img,svg,video{max-width:100%;display:block}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit;color:inherit}
button{background:none;border:0;cursor:pointer}
table{border-collapse:collapse;width:100%}

/* ============ 1. TOKENS ============ */
:root{
  --abyss:#04121F;
  --hull:#0A2540;
  --panel:#123A5E;
  --cyan:#2BE8D0;
  --cyan-soft:#7FF3E4;
  --orange:#FF8A3D;
  --amber:#FFC48A;
  --mist:#EAF4F8;
  --slate:#8FA8B8;
  --ink:#01070D;
  --line:rgba(127,243,228,.18);
  --line-strong:rgba(43,232,208,.55);
  --font-display:'Barlow Condensed','Oswald','PingFang SC','Source Han Sans SC','Microsoft YaHei',sans-serif;
  --font-mono:'JetBrains Mono','IBM Plex Mono','Roboto Mono','Courier New',monospace;
  --font-body:'Noto Sans SC','Source Han Sans SC','PingFang SC','Microsoft YaHei',sans-serif;
  --shell:1240px;
  --pad:clamp(18px,5vw,72px);
  --radius:12px;
  --radius-lg:20px;
  --ease:cubic-bezier(.22,.61,.36,1);
  --header-offset:112px;
}

/* ============ 2. BASE ============ */
body{
  font-family:var(--font-body);
  font-size:17px;
  line-height:1.75;
  color:var(--mist);
  background-color:var(--abyss);
  background-image:
    radial-gradient(120% 80% at 78% -12%,rgba(18,58,94,.9) 0%,rgba(4,18,31,0) 62%),
    radial-gradient(90% 62% at 4% 38%,rgba(43,232,208,.09) 0%,rgba(4,18,31,0) 56%),
    radial-gradient(80% 70% at 92% 102%,rgba(255,138,61,.08) 0%,rgba(4,18,31,0) 60%);
  background-attachment:fixed;
  min-height:100vh;
  -webkit-font-smoothing:antialiased;
  overflow-x:hidden;
}
body::before{
  content:"";
  position:fixed;
  inset:0;
  pointer-events:none;
  z-index:3;
  background:repeating-linear-gradient(0deg,rgba(127,243,228,.035) 0 1px,rgba(0,0,0,0) 1px 4px);
  opacity:.5;
}
main{display:block;position:relative;z-index:2}
:focus-visible{outline:2px solid var(--cyan);outline-offset:3px;border-radius:4px}

.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums;letter-spacing:.08em}
.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}

.skip-link{
  position:absolute;left:14px;top:-70px;z-index:200;
  background:var(--cyan);color:var(--ink);
  padding:11px 20px;font-weight:700;font-size:14px;letter-spacing:.06em;
  border-radius:0 0 10px 10px;
  transition:top .2s var(--ease);
}
.skip-link:focus{top:0}

/* ============ 3. LAYOUT ============ */
.shell{width:100%;max-width:var(--shell);margin-inline:auto;padding-inline:var(--pad)}
.section{position:relative;padding:clamp(48px,7vw,96px) 0}
.section__head{display:flex;flex-direction:column;gap:14px;max-width:66ch;position:relative;z-index:1}
.section-no{font-family:var(--font-mono);font-size:12px;letter-spacing:.3em;color:var(--cyan)}
.eyebrow{display:inline-flex;align-items:center;gap:10px;font-family:var(--font-mono);font-size:12px;letter-spacing:.22em;color:var(--cyan)}
.eyebrow::before{content:"";width:28px;height:1px;background:var(--cyan)}
.display-title{font-family:var(--font-display);font-weight:800;font-size:clamp(38px,6vw,86px);line-height:.98;letter-spacing:-.02em;color:var(--mist)}
.lead{font-size:clamp(17px,1.5vw,20px);line-height:1.7;color:#CFE2EC;max-width:62ch}
.annotation{font-size:12px;letter-spacing:.18em;color:var(--slate)}
.annotation--vertical{writing-mode:vertical-rl;letter-spacing:.3em;text-orientation:mixed}
.rule{height:1px;border:0;margin:clamp(28px,5vw,56px) 0;background:linear-gradient(90deg,rgba(43,232,208,.55),rgba(143,168,184,.12) 45%,rgba(255,138,61,.42))}

.grid-12{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));gap:24px}
.span-3{grid-column:span 3}
.span-4{grid-column:span 4}
.span-5{grid-column:span 5}
.span-6{grid-column:span 6}
.span-7{grid-column:span 7}
.span-8{grid-column:span 8}
.span-12{grid-column:span 12}

/* ============ 4. COMPONENTS ============ */
.panel{
  position:relative;
  background:linear-gradient(160deg,rgba(18,58,94,.95),rgba(10,37,64,.88));
  border:1px solid var(--line);
  border-radius:var(--radius-lg);
  padding:clamp(20px,3vw,34px);
}
.panel--cut{
  border-radius:var(--radius);
  clip-path:polygon(0 0,100% 0,100% calc(100% - 34px),calc(100% - 34px) 100%,0 100%);
}
.panel--stack{margin-top:-24px}

.media-frame{
  position:relative;
  isolation:isolate;
  overflow:hidden;
  border-radius:var(--radius);
  border:1px solid var(--line-strong);
  aspect-ratio:var(--ratio,16/10);
  background:linear-gradient(150deg,rgba(43,232,208,.16),rgba(10,37,64,.92) 46%,rgba(255,138,61,.14));
}
.media-frame img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;z-index:1;filter:saturate(.95) contrast(1.05)}
.media-frame::before{
  content:"";position:absolute;inset:0;z-index:2;pointer-events:none;opacity:.7;
  background:repeating-linear-gradient(115deg,rgba(127,243,228,.09) 0 1px,rgba(0,0,0,0) 1px 22px);
}
.media-frame::after{
  content:"";position:absolute;inset:0;z-index:3;pointer-events:none;
  box-shadow:inset 0 0 70px rgba(4,18,31,.85);
}
.media-frame__cap{
  position:absolute;left:12px;bottom:12px;z-index:4;
  font-family:var(--font-mono);font-size:11px;letter-spacing:.16em;
  color:var(--cyan-soft);background:rgba(1,7,13,.74);
  border:1px solid var(--line);padding:5px 11px;border-radius:6px;
}
.media-frame--wide{--ratio:21/9}
.media-frame--tall{--ratio:4/5}
.media-frame--cut{
  border-radius:var(--radius) 0 0 var(--radius);
  clip-path:polygon(0 0,100% 0,100% calc(100% - 28px),calc(100% - 28px) 100%,0 100%);
}
.media-frame--tilt{transform:perspective(900px) rotateY(-7deg) rotateX(3deg)}

.tag{
  display:inline-flex;align-items:center;gap:6px;
  font-family:var(--font-mono);font-size:11px;letter-spacing:.16em;
  padding:4px 10px;border-radius:6px;
  border:1px solid var(--line);background:rgba(43,232,208,.08);color:var(--cyan-soft);
}
.tag--orange{border-color:rgba(255,138,61,.4);background:rgba(255,138,61,.1);color:var(--amber)}

.chip{
  display:inline-flex;align-items:center;gap:6px;
  padding:5px 13px;border-radius:999px;
  font-family:var(--font-mono);font-size:12px;letter-spacing:.1em;
  border:1px solid var(--line);background:rgba(18,58,94,.4);color:var(--slate);
}
.chip--cyan{border-color:var(--line-strong);color:var(--cyan-soft)}
.chip--orange{border-color:rgba(255,138,61,.45);color:var(--amber)}

.dot{
  width:7px;height:7px;border-radius:50%;flex:0 0 auto;
  background:var(--cyan);box-shadow:0 0 0 3px rgba(43,232,208,.18);
  animation:pulse 2.6s ease-in-out infinite;
}
@keyframes pulse{0%,100%{opacity:.5}50%{opacity:1}}

.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:13px 24px;border-radius:999px;border:1px solid transparent;
  font-size:15px;font-weight:700;letter-spacing:.04em;cursor:pointer;
  transition:transform .18s var(--ease),background-color .18s var(--ease),color .18s var(--ease),border-color .18s var(--ease);
}
.btn--accent{background:var(--orange);color:var(--ink)}
.btn--accent:hover{background:var(--amber);transform:translateY(-2px)}
.btn--cyan{background:var(--cyan);color:var(--ink)}
.btn--cyan:hover{background:var(--cyan-soft);transform:translateY(-2px)}
.btn--ghost{border-color:var(--line-strong);color:var(--cyan-soft);background:rgba(43,232,208,.05)}
.btn--ghost:hover{background:rgba(43,232,208,.14);transform:translateY(-2px)}
.btn--sm{padding:9px 17px;font-size:13px}

.callout{
  display:flex;gap:14px;align-items:flex-start;
  padding:16px 18px;border-radius:var(--radius);
  border:1px solid rgba(255,138,61,.35);
  background:linear-gradient(120deg,rgba(255,138,61,.13),rgba(10,37,64,.25));
}
.callout__key{font-family:var(--font-mono);font-size:12px;letter-spacing:.2em;color:var(--orange);flex:0 0 auto;padding-top:3px}
.callout p{font-size:15px;line-height:1.7;color:#DCEAF2;max-width:60ch}

.stat{
  display:flex;flex-direction:column;gap:2px;
  padding:16px 18px;border-left:2px solid var(--cyan);
  background:rgba(18,58,94,.35);
  border-radius:0 var(--radius) var(--radius) 0;
}
.stat__value{font-family:var(--font-mono);font-size:clamp(24px,3vw,34px);line-height:1.2;color:var(--mist)}
.stat__label{font-size:12px;letter-spacing:.16em;color:var(--slate)}

.line-field{position:absolute;inset:0;overflow:hidden;pointer-events:none;z-index:0}
.line-field::before,.line-field::after{
  content:"";position:absolute;border-radius:50%;filter:blur(46px);
  animation:breathe 10s ease-in-out infinite;
}
.line-field::before{
  width:46vw;height:46vw;left:-12vw;top:-14vw;
  background:radial-gradient(circle,rgba(43,232,208,.22),rgba(0,0,0,0) 68%);
}
.line-field::after{
  width:38vw;height:38vw;right:-10vw;bottom:-16vw;animation-delay:-4.5s;
  background:radial-gradient(circle,rgba(255,138,61,.17),rgba(0,0,0,0) 70%);
}
@keyframes breathe{0%,100%{opacity:.3;transform:scale(1)}50%{opacity:.62;transform:scale(1.07)}}

.breadcrumbs{padding-top:18px;font-family:var(--font-mono);font-size:12px;letter-spacing:.14em;color:var(--slate)}
.breadcrumbs__list{display:flex;flex-wrap:wrap;align-items:center;gap:8px}
.breadcrumbs__list li{display:inline-flex;align-items:center;gap:8px}
.breadcrumbs__list li+li::before{content:"/";color:rgba(143,168,184,.5)}
.breadcrumbs a:hover{color:var(--cyan-soft)}
.breadcrumbs [aria-current="page"]{color:var(--mist)}

[data-reveal]{opacity:0;transform:translateY(16px);transition:opacity .32s var(--ease),transform .32s var(--ease)}
[data-reveal].is-in{opacity:1;transform:none}

/* 左侧章节索引条 */
.anchor-rail{display:none}
.anchor-rail__list{display:flex;flex-direction:column;gap:12px}
.anchor-rail__link{
  display:inline-flex;align-items:center;gap:8px;
  writing-mode:vertical-rl;text-orientation:mixed;
  font-size:11px;letter-spacing:.28em;color:var(--slate);
  padding:8px 6px;border-left:2px solid transparent;
  transition:color .18s var(--ease),border-color .18s var(--ease);
}
.anchor-rail__link:hover{color:var(--cyan-soft)}
.anchor-rail__link[aria-current="true"]{color:var(--cyan);border-left-color:var(--cyan)}

/* ============ 5. HEADER ============ */
.site-header{
  position:sticky;top:0;z-index:60;
  background:rgba(4,18,31,.94);
  backdrop-filter:blur(10px);
  border-bottom:1px solid var(--line);
}
.header-rail{
  background:linear-gradient(90deg,rgba(1,7,13,.92),rgba(10,37,94,.75) 60%,rgba(18,58,94,.6));
  border-bottom:1px solid rgba(127,243,228,.1);
}
.header-rail__inner{display:flex;align-items:center;justify-content:space-between;gap:16px;min-height:33px;padding-block:6px}
.header-rail__meta{
  display:inline-flex;align-items:center;gap:9px;
  font-size:12px;letter-spacing:.1em;color:var(--slate);
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis;
}
.header-rail__meta .mono{color:var(--cyan);letter-spacing:.2em;font-size:11px}
.header-rail__util{display:flex;align-items:center;gap:20px;flex:0 0 auto}
.header-rail__util a{font-size:12px;letter-spacing:.14em;color:var(--slate);transition:color .18s var(--ease)}
.header-rail__util a:hover{color:var(--cyan-soft)}

.header-main__inner{position:relative;display:flex;align-items:center;gap:clamp(14px,3vw,40px);padding-block:12px}
.brand{display:inline-flex;align-items:center;gap:12px;flex:0 0 auto}
.brand__mark{
  position:relative;width:36px;height:36px;flex:0 0 auto;
  display:grid;place-items:center;
  border:1px solid var(--line-strong);border-radius:10px;
  background:linear-gradient(140deg,rgba(43,232,208,.2),rgba(255,138,61,.12));
}
.brand__mark-line{
  width:16px;height:2px;border-radius:2px;background:var(--cyan);
  box-shadow:0 -6px 0 -.5px var(--cyan),0 6px 0 -.5px var(--orange);
}
.brand__text{display:flex;flex-direction:column;line-height:1.22}
.brand__name{font-family:var(--font-display);font-weight:800;font-size:21px;letter-spacing:.02em;color:var(--mist)}
.brand__tag{font-family:var(--font-mono);font-size:11px;letter-spacing:.14em;color:var(--slate)}

.nav-toggle{
  display:none;margin-left:auto;align-items:center;gap:9px;
  padding:9px 13px;border:1px solid var(--line);border-radius:10px;
  font-size:12px;letter-spacing:.18em;color:var(--mist);
  transition:border-color .18s var(--ease),color .18s var(--ease);
}
.nav-toggle:hover{border-color:var(--line-strong);color:var(--cyan-soft)}
.nav-toggle__bars{display:flex;flex-direction:column;gap:4px;width:18px}
.nav-toggle__bars i{display:block;height:2px;border-radius:2px;background:var(--cyan);transition:transform .22s var(--ease),opacity .22s var(--ease)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(1){transform:translateY(6px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(2){opacity:0}
.nav-toggle[aria-expanded="true"] .nav-toggle__bars i:nth-child(3){transform:translateY(-6px) rotate(-45deg)}

.site-nav{margin-left:auto;display:flex;align-items:center;gap:clamp(12px,2vw,28px)}
.site-nav__list{display:flex;align-items:center;gap:clamp(6px,1.1vw,18px)}
.site-nav__item{display:flex}
.site-nav__link{
  position:relative;display:inline-flex;flex-direction:column;gap:1px;
  padding:6px 2px 9px;color:var(--slate);
  transition:color .18s var(--ease),transform .18s var(--ease);
}
.site-nav__link:hover{color:var(--cyan-soft);transform:translateY(-2px)}
.site-nav__no{font-family:var(--font-mono);font-size:10px;letter-spacing:.2em;color:rgba(143,168,184,.72)}
.site-nav__label{font-size:14px;letter-spacing:.03em;white-space:nowrap}
.site-nav__link::after{
  content:"";position:absolute;left:0;right:0;bottom:0;height:2px;
  background:var(--cyan);transform:scaleX(0);transform-origin:left;
  transition:transform .22s var(--ease);
}
.site-nav__link:hover::after{transform:scaleX(.45)}
.site-nav__link[aria-current="page"]{color:var(--mist)}
.site-nav__link[aria-current="page"] .site-nav__no{color:var(--cyan)}
.site-nav__link[aria-current="page"]::after{transform:scaleX(1)}
.site-nav__cta{flex:0 0 auto}

.scroll-progress{
  position:absolute;left:0;right:0;bottom:-1px;height:2px;
  background:rgba(127,243,228,.12);overflow:hidden;
}
.scroll-progress span{
  display:block;width:100%;height:100%;
  transform:scaleX(0);transform-origin:left;
  background:linear-gradient(90deg,var(--cyan),var(--cyan-soft) 55%,var(--orange));
}

/* ============ 6. FOOTER ============ */
.site-footer{margin-top:clamp(48px,8vw,110px);background:linear-gradient(180deg,rgba(4,18,31,.55),var(--ink) 38%);border-top:1px solid var(--line)}
.footer-edge{
  height:22px;
  background:linear-gradient(90deg,rgba(43,232,208,.6),rgba(18,58,94,.15) 44%,rgba(255,138,61,.5));
  clip-path:polygon(0 0,100% 0,100% 34%,0 100%);
}
.footer-inner{
  display:grid;grid-template-columns:1.35fr 2.2fr;
  gap:clamp(26px,5vw,64px);
  padding-block:clamp(36px,6vw,72px);
}
.footer-brand{position:relative;z-index:1}
.footer-brand__name{font-family:var(--font-display);font-weight:800;font-size:clamp(26px,3.2vw,40px);line-height:1.05;letter-spacing:.01em;color:var(--mist)}
.footer-brand__tag{margin-top:8px;font-family:var(--font-mono);font-size:12px;letter-spacing:.16em;color:var(--slate)}
.footer-chips{display:flex;flex-wrap:wrap;gap:8px;margin-top:18px}
.footer-note{margin-top:16px;font-size:13px;line-height:1.85;color:rgba(143,168,184,.92);max-width:46ch}

.footer-cols{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:22px}
.footer-col__title{
  font-family:var(--font-mono);font-size:11px;letter-spacing:.24em;
  text-transform:uppercase;color:var(--cyan);margin-bottom:14px;
}
.footer-col__list{display:flex;flex-direction:column;gap:10px}
.footer-col__list a{
  display:inline-block;font-size:15px;color:var(--slate);
  transition:color .18s var(--ease),transform .18s var(--ease);
}
.footer-col__list a:hover{color:var(--mist);transform:translateX(3px)}

.footer-base{border-top:1px dashed rgba(143,168,184,.25);background:rgba(1,7,13,.62)}
.footer-base__inner{display:flex;flex-direction:column;gap:14px;padding-block:22px 34px}
.footer-legal{display:flex;flex-wrap:wrap;align-items:center;gap:10px 20px;font-size:12px;letter-spacing:.12em;color:var(--slate)}
.footer-legal__item a{color:var(--slate);border-bottom:1px dashed rgba(143,168,184,.4);transition:color .18s var(--ease),border-color .18s var(--ease)}
.footer-legal__item a:hover{color:var(--cyan-soft);border-color:var(--line-strong)}
.footer-legal .mono{color:var(--slate);letter-spacing:.16em}
.footer-contact{font-size:13px;line-height:1.9;color:var(--slate);word-break:break-word}
.footer-contact strong{color:var(--mist);font-weight:600}
.footer-copy{font-family:var(--font-mono);font-size:12px;letter-spacing:.12em;color:rgba(143,168,184,.8)}
.footer-copy [data-year]{color:var(--cyan-soft)}

/* ============ 7. RESPONSIVE ============ */
@media (min-width:1280px){
  .anchor-rail{
    display:block;position:fixed;left:max(14px,2.2vw);top:50%;
    transform:translateY(-50%);z-index:40;
  }
}
@media (max-width:1199px){
  .brand__tag{display:none}
  .brand__name{font-size:19px}
}
@media (max-width:1099px){
  .nav-toggle{display:inline-flex}
  .site-nav{
    position:absolute;left:0;right:0;top:100%;margin-left:0;
    flex-direction:column;align-items:stretch;gap:0;
    padding:6px var(--pad) 22px;
    background:linear-gradient(180deg,rgba(6,24,40,.99),rgba(4,18,31,.99));
    border-bottom:1px solid var(--line);
    opacity:0;visibility:hidden;pointer-events:none;
    transform:translateY(-10px);
    transition:opacity .22s var(--ease),transform .22s var(--ease),visibility .22s var(--ease);
  }
  [data-open="true"] .site-nav{opacity:1;visibility:visible;pointer-events:auto;transform:none}
  .site-nav__list{flex-direction:column;align-items:stretch;gap:0}
  .site-nav__item{border-bottom:1px dashed rgba(143,168,184,.22)}
  .site-nav__link{flex-direction:row;align-items:baseline;gap:14px;padding:15px 2px}
  .site-nav__link::after{display:none}
  .site-nav__link:hover{transform:none;color:var(--cyan-soft)}
  .site-nav__link[aria-current="page"] .site-nav__label{color:var(--cyan)}
  .site-nav__label{font-size:16px}
  .site-nav__cta{margin-top:18px;width:100%}
  .footer-inner{grid-template-columns:1fr}
  .footer-note{max-width:none}
}
@media (max-width:1024px){
  .span-3,.span-4,.span-5{grid-column:span 6}
}
@media (max-width:720px){
  body{font-size:16px}
  .header-rail__util{display:none}
  .grid-12{gap:16px}
  .span-3,.span-4,.span-5,.span-6,.span-7,.span-8{grid-column:span 12}
  .footer-cols{grid-template-columns:1fr;gap:26px}
  .media-frame--tilt{transform:none}
  .panel--stack{margin-top:-16px}
}

/* ============ 8. MOTION SAFETY ============ */
@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{
    animation-duration:.001ms!important;
    animation-iteration-count:1!important;
    transition-duration:.001ms!important;
  }
  html{scroll-behavior:auto}
  [data-reveal]{opacity:1;transform:none}
  .line-field::before,.line-field::after{opacity:.35}
}