/* ============ 01. Reset ============ */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body,h1,h2,h3,h4,h5,p,ul,ol,li,figure,blockquote,dl,dd{margin:0}
ul,ol{list-style:none;padding:0}
img,svg,video{max-width:100%;height:auto}
a{color:inherit;text-decoration:none}
button{font:inherit;color:inherit;background:none;border:0;padding:0;cursor:pointer}
:focus-visible{outline:2px solid var(--cyan-soft);outline-offset:3px;border-radius:3px}

/* ============ 02. Tokens ============ */
:root{
  --deep:#0B2545;
  --abyss:#071A33;
  --navy:#143A66;
  --line:#24456E;
  --cyan:#29E0D2;
  --cyan-soft:#7FF3E8;
  --orange:#FF7A2F;
  --orange-soft:#FFB37A;
  --white:#F4F8FF;
  --mist:#93A7C4;
  --paper:#EEF3FA;
  --ink:#0E1622;
  --ink-soft:#4A5C78;
  --font-display:"Noto Serif SC","Source Han Serif SC","Songti SC",Georgia,"Times New Roman",serif;
  --font-ui:Inter,"Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --font-body:"Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,sans-serif;
  --rail-w:320px;
  --shell-max:1180px;
  --pad-x:clamp(18px,4vw,48px);
  --cut:18px;
  --cut-lg:28px;
  --ease:cubic-bezier(.22,.61,.36,1);
}

/* ============ 03. Base ============ */
body{
  font-family:var(--font-body);
  font-size:16px;
  line-height:1.75;
  color:var(--white);
  background:var(--deep);
  text-rendering:optimizeLegibility;
  overflow-x:hidden;
}
body::before{
  content:"";
  position:fixed;
  inset:0;
  z-index:0;
  pointer-events:none;
  background-image:
    linear-gradient(to right,rgba(36,69,110,.52) 1px,transparent 1px),
    linear-gradient(to bottom,rgba(36,69,110,.52) 1px,transparent 1px);
  background-size:96px 96px;
  opacity:.42;
}
body::after{
  content:"";
  position:fixed;
  inset:0;
  z-index:0;
  pointer-events:none;
  background:
    radial-gradient(760px 520px at 84% -10%,rgba(41,224,210,.16),transparent 70%),
    radial-gradient(620px 480px at 4% 106%,rgba(255,122,47,.12),transparent 72%);
}
#main-content{position:relative;z-index:1;display:block}

h1,h2,h3,h4{font-family:var(--font-display);font-weight:700;line-height:1.2;letter-spacing:-.02em;text-wrap:balance}
p{text-wrap:pretty}
.display{font-size:clamp(38px,7.4vw,96px);line-height:1.02;letter-spacing:-.03em}
.h2{font-size:clamp(26px,3.4vw,44px)}
.h3{font-size:clamp(19px,2vw,24px);font-family:var(--font-ui);letter-spacing:-.01em}
.lede{font-size:clamp(15px,1.3vw,18px);line-height:1.7;color:var(--mist);max-width:38em}
.muted{color:var(--mist);font-size:14px}
.num{font-family:var(--font-ui);font-variant-numeric:tabular-nums;font-feature-settings:"tnum" 1}
.eyebrow{
  display:inline-flex;align-items:center;gap:10px;
  font-family:var(--font-ui);font-size:11px;font-weight:700;
  letter-spacing:.22em;text-transform:uppercase;color:var(--cyan);
}
.eyebrow::before{content:"";width:22px;height:1px;background:var(--cyan);display:block}

/* ============ 04. Layout utils ============ */
.shell{width:100%;max-width:var(--shell-max);margin-inline:auto;padding-inline:var(--pad-x)}
.section{position:relative;padding-block:clamp(48px,7vw,96px)}
.section--tight{padding-block:clamp(32px,5vw,64px)}
.section--paper{background:var(--paper);color:var(--ink)}
.section--paper .lede,.section--paper .muted{color:var(--ink-soft)}
.section--paper .eyebrow{color:#0F7C74}
.section--paper .eyebrow::before{background:#0F7C74}
.section__head{
  display:flex;flex-wrap:wrap;align-items:flex-end;justify-content:space-between;
  gap:14px 28px;margin-bottom:clamp(20px,3vw,36px);
}
.divider{height:1px;background:var(--line);border:0;margin:0}
.trace{position:relative;height:1px;overflow:hidden;background:linear-gradient(90deg,transparent,rgba(41,224,210,.55),transparent)}
.trace::after{
  content:"";position:absolute;top:0;left:0;width:35%;height:100%;
  background:linear-gradient(90deg,transparent,var(--orange),transparent);
  animation:trace-move 3s linear infinite;
}
@keyframes trace-move{from{transform:translateX(-100%)}to{transform:translateX(320%)}}

.grid{display:grid;gap:clamp(16px,2.5vw,28px);grid-template-columns:minmax(0,1fr)}
@media (min-width:640px){
  .grid--2{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media (min-width:900px){
  .grid--3{grid-template-columns:repeat(3,minmax(0,1fr))}
}

/* ============ 05. Chapter ============ */
.chapter{display:grid;grid-template-columns:minmax(0,1fr);gap:14px}
.chapter__num{
  font-family:var(--font-display);font-weight:700;font-style:normal;
  font-size:clamp(56px,9vw,120px);line-height:.86;letter-spacing:-.05em;
  color:var(--orange);font-variant-numeric:tabular-nums;
}
.chapter__body{max-width:40em}
.chapter__body p+p{margin-top:14px}
@media (min-width:768px){
  .chapter{grid-template-columns:minmax(96px,168px) minmax(0,1fr);gap:clamp(20px,3vw,44px);align-items:start}
}

/* ============ 06. Panel / Badge / Media ============ */
.panel{
  background:var(--navy);
  border:1px solid var(--line);
  padding:clamp(20px,3vw,32px);
  clip-path:polygon(var(--cut) 0,100% 0,100% calc(100% - var(--cut)),calc(100% - var(--cut)) 100%,0 100%,0 var(--cut));
}
.panel--deep{background:var(--abyss)}
.panel--paper{background:var(--paper);color:var(--ink);border-color:#C9D7EA}
.panel--paper .muted{color:var(--ink-soft)}
.badge{
  display:inline-flex;align-items:center;gap:6px;
  padding:4px 12px;font-family:var(--font-ui);font-size:12px;font-weight:600;
  letter-spacing:.06em;color:var(--cyan-soft);
  border:1px solid rgba(41,224,210,.5);background:rgba(41,224,210,.08);
  clip-path:polygon(8px 0,100% 0,100% calc(100% - 8px),calc(100% - 8px) 100%,0 100%,0 8px);
}
.badge--orange{color:var(--orange-soft);border-color:rgba(255,122,47,.55);background:rgba(255,122,47,.12)}

.media{
  position:relative;display:block;overflow:hidden;aspect-ratio:16/9;
  background:linear-gradient(150deg,var(--navy),var(--abyss));
  border:1px solid var(--line);
  clip-path:polygon(var(--cut-lg) 0,100% 0,100% calc(100% - var(--cut-lg)),calc(100% - var(--cut-lg)) 100%,0 100%,0 var(--cut-lg));
}
.media--wide{aspect-ratio:21/9}
.media--square{aspect-ratio:1/1}
.media--tall{aspect-ratio:4/5}
.media img,.media svg,.media video{display:block;width:100%;height:100%;object-fit:cover}
.media__placeholder{
  position:absolute;inset:0;display:grid;place-content:center;gap:8px;text-align:center;
  background-image:
    linear-gradient(to right,rgba(36,69,110,.7) 1px,transparent 1px),
    linear-gradient(to bottom,rgba(36,69,110,.7) 1px,transparent 1px);
  background-size:44px 44px;
}
.media__placeholder::after{
  content:"";width:74px;height:74px;justify-self:center;
  border:1px solid rgba(41,224,210,.5);transform:rotate(45deg);
  background:radial-gradient(circle,rgba(41,224,210,.28),transparent 70%);
}
.media__caption{margin-top:10px;font-size:13px;color:var(--mist)}

/* ============ 07. Buttons ============ */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:12px 20px;font-family:var(--font-ui);font-weight:700;font-size:14px;
  letter-spacing:.02em;text-align:center;cursor:pointer;
  border:1px solid transparent;
  clip-path:polygon(var(--cut) 0,100% 0,100% calc(100% - var(--cut)),calc(100% - var(--cut)) 100%,0 100%,0 var(--cut));
  transition:background-color .2s var(--ease),color .2s var(--ease),border-color .2s var(--ease),transform .2s var(--ease);
}
.btn:active{transform:translateY(1px)}
.btn--primary{background:var(--cyan);color:var(--abyss)}
.btn--primary:hover{background:var(--cyan-soft)}
.btn--ghost{background:rgba(41,224,210,.06);border-color:rgba(41,224,210,.45);color:var(--cyan-soft)}
.btn--ghost:hover{background:rgba(41,224,210,.16);border-color:var(--cyan);color:var(--white)}
.btn--orange{background:var(--orange);color:var(--abyss)}
.btn--orange:hover{background:var(--orange-soft)}
.btn--block{width:100%}

/* ============ 08. Tabs ============ */
.tabs{width:100%}
.tabs__list{display:flex;flex-wrap:wrap;gap:4px;border-bottom:1px solid var(--line);margin-bottom:20px}
.tabs__tab{
  padding:11px 16px;font-family:var(--font-ui);font-size:14px;font-weight:600;
  color:var(--mist);border-bottom:2px solid transparent;margin-bottom:-1px;
  transition:color .2s var(--ease),border-color .2s var(--ease),background-color .2s var(--ease);
}
.tabs__tab:hover{color:var(--white);background:rgba(41,224,210,.06)}
.tabs__tab[aria-selected="true"]{color:var(--cyan);border-bottom-color:var(--cyan);background:rgba(41,224,210,.1)}
.tabs__panel:focus-visible{outline-offset:6px}
.tabs__panel[hidden]{display:none}

/* ============ 09. Breadcrumb ============ */
.breadcrumb{
  display:flex;flex-wrap:wrap;align-items:center;gap:8px;
  font-family:var(--font-ui);font-size:12px;letter-spacing:.04em;color:var(--mist);
}
.breadcrumb li{display:flex;align-items:center;gap:8px}
.breadcrumb li+li::before{content:"/";color:var(--line)}
.breadcrumb a:hover{color:var(--cyan-soft)}
.breadcrumb [aria-current="page"]{color:var(--white)}

/* ============ 10. Skip link ============ */
.skip-link{
  position:absolute;left:16px;top:-80px;z-index:200;
  padding:10px 18px;background:var(--cyan);color:var(--abyss);
  font-family:var(--font-ui);font-size:14px;font-weight:700;
  clip-path:polygon(10px 0,100% 0,100% calc(100% - 10px),calc(100% - 10px) 100%,0 100%,0 10px);
  transition:top .2s var(--ease);
}
.skip-link:focus{top:16px}

/* ============ 11. Header ============ */
.site-header{
  position:sticky;top:0;z-index:80;
  background:linear-gradient(180deg,rgba(7,26,51,.98),rgba(11,37,69,.94));
  border-bottom:1px solid var(--line);
  box-shadow:0 10px 30px rgba(2,10,22,.45);
}
.site-header__top{
  display:flex;align-items:center;justify-content:space-between;gap:14px;
  padding:12px 18px;
}
.brand{display:flex;align-items:center;gap:11px;min-width:0}
.brand__mark{
  flex:0 0 auto;width:38px;height:38px;display:grid;place-items:center;
  font-family:var(--font-ui);font-weight:800;font-size:13px;letter-spacing:.02em;
  color:var(--abyss);background:linear-gradient(135deg,var(--cyan),var(--cyan-soft));
  clip-path:polygon(10px 0,100% 0,100% calc(100% - 10px),calc(100% - 10px) 100%,0 100%,0 10px);
}
.brand__block{display:flex;flex-direction:column;line-height:1.3;min-width:0}
.brand__name{font-family:var(--font-ui);font-weight:700;font-size:16px;letter-spacing:.02em;color:var(--white)}
.brand__tagline{font-size:11px;letter-spacing:.03em;color:var(--mist);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}

.nav-toggle{
  display:inline-flex;align-items:center;gap:9px;flex:0 0 auto;
  padding:9px 13px;border:1px solid var(--line);background:rgba(20,58,102,.7);
  color:var(--white);font-family:var(--font-ui);font-size:12.5px;font-weight:600;letter-spacing:.06em;
  clip-path:polygon(10px 0,100% 0,100% calc(100% - 10px),calc(100% - 10px) 100%,0 100%,0 10px);
  transition:border-color .2s var(--ease),background-color .2s var(--ease);
}
.nav-toggle:hover{border-color:rgba(41,224,210,.6);background:rgba(41,224,210,.12)}
.nav-toggle__bars{display:grid;gap:4px;width:16px}
.nav-toggle__bar{display:block;height:2px;width:100%;background:var(--cyan);transition:transform .22s var(--ease),opacity .22s var(--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)}

.nav{
  position:absolute;left:0;right:0;top:100%;
  display:flex;flex-direction:column;gap:22px;
  padding:20px 18px 26px;
  background:var(--abyss);
  border-bottom:1px solid var(--line);
  box-shadow:0 26px 44px rgba(2,10,22,.6);
  max-height:calc(100vh - 70px);overflow-y:auto;
  opacity:0;visibility:hidden;transform:translateY(-10px);
  transition:opacity .24s var(--ease),transform .24s var(--ease),visibility .24s linear;
}
.nav[data-open]{opacity:1;visibility:visible;transform:translateY(0)}
.nav__caption,.quick__caption{
  font-family:var(--font-ui);font-size:10.5px;font-weight:700;
  letter-spacing:.24em;text-transform:uppercase;color:var(--mist);
  padding-bottom:10px;border-bottom:1px solid var(--line);
}
.nav__list{display:flex;flex-direction:column;gap:2px;margin-top:12px}
.nav__link{
  display:flex;align-items:center;gap:11px;
  padding:10px 12px;font-family:var(--font-ui);font-size:15px;font-weight:600;
  color:var(--white);border-left:2px solid transparent;
  transition:background-color .2s var(--ease),color .2s var(--ease),border-color .2s var(--ease);
}
.nav__link::before{content:"";width:6px;height:6px;flex:0 0 auto;background:var(--line);transform:rotate(45deg);transition:background-color .2s var(--ease)}
.nav__link:hover{background:rgba(41,224,210,.08);color:var(--cyan-soft)}
.nav__link:hover::before{background:var(--cyan)}
.nav__link[aria-current="page"]{
  color:var(--cyan);border-left-color:var(--orange);
  background:linear-gradient(90deg,rgba(41,224,210,.16),rgba(41,224,210,0));
}
.nav__link[aria-current="page"]::before{background:var(--orange)}

.rail-actions{display:grid;gap:10px}
.quick{display:grid;gap:10px}
.quick__list{display:grid;gap:4px}
.quick__link{
  display:inline-flex;align-items:center;gap:10px;
  padding:6px 2px;font-size:13.5px;color:var(--mist);
  transition:color .2s var(--ease);
}
.quick__link:hover{color:var(--cyan-soft)}
.quick__dot{width:6px;height:6px;flex:0 0 auto;background:var(--cyan);transform:rotate(45deg)}

.rail-note{display:none;flex-direction:column;gap:5px}
.rail-note__label{font-family:var(--font-ui);font-size:10px;font-weight:700;letter-spacing:.2em;text-transform:uppercase;color:var(--mist)}
.rail-note__value{font-family:var(--font-ui);font-size:12px;color:var(--cyan-soft);word-break:break-all}

.scroll-progress{
  position:fixed;top:0;left:0;right:0;height:3px;z-index:90;
  background:rgba(244,248,255,.08);pointer-events:none;
}
.scroll-progress__bar{
  display:block;width:100%;height:100%;transform:scaleX(0);transform-origin:0 50%;
  background:linear-gradient(90deg,var(--cyan),var(--orange));
  will-change:transform;
}

/* ============ 12. Footer ============ */
.site-footer{
  position:relative;z-index:1;
  background:var(--abyss);
  border-top:1px solid var(--line);
  padding-block:clamp(40px,6vw,72px) 26px;
  color:var(--mist);
}
.footer__grid{display:grid;grid-template-columns:minmax(0,1fr);gap:clamp(26px,3.4vw,44px)}
.footer__brand{display:flex;flex-direction:column;align-items:flex-start;gap:10px}
.footer__name{font-family:var(--font-display);font-size:22px;font-weight:700;color:var(--white);letter-spacing:-.01em}
.footer__tagline{font-family:var(--font-ui);font-size:12.5px;letter-spacing:.04em;color:var(--cyan-soft)}
.footer__cta{margin-top:8px}
.footer__facts{display:grid;gap:8px;margin-top:18px;width:100%}
.footer__fact{display:flex;flex-wrap:wrap;gap:4px 12px;font-size:13px;line-height:1.65}
.footer__fact-label{flex:0 0 64px;color:var(--mist);letter-spacing:.06em}
.footer__fact-value{color:var(--white);word-break:break-all}
.footer__col{display:block}
.footer__col-title{
  font-family:var(--font-ui);font-size:12.5px;font-weight:700;
  letter-spacing:.16em;color:var(--white);text-transform:uppercase;
  padding-bottom:12px;border-bottom:1px solid var(--line);
}
.footer__links{display:grid;gap:11px;margin-top:16px}
.footer__link{
  display:inline-flex;align-items:center;gap:10px;
  font-size:14px;color:var(--mist);
  transition:color .2s var(--ease);
}
.footer__link::before{
  content:"";width:5px;height:5px;flex:0 0 auto;
  border:1px solid var(--line);transform:rotate(45deg);
  transition:background-color .2s var(--ease),border-color .2s var(--ease);
}
.footer__link:hover{color:var(--cyan-soft)}
.footer__link:hover::before{background:var(--cyan);border-color:var(--cyan)}
.footer__base{
  display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:10px 24px;
  margin-top:clamp(28px,4vw,48px);padding-top:20px;
  border-top:1px solid var(--line);
  font-family:var(--font-ui);font-size:12px;letter-spacing:.04em;color:var(--mist);
}
.footer__copy{max-width:52ch}

/* ============ 13. Desktop rail ============ */
@media (min-width:1024px){
  body{padding-left:var(--rail-w)}
  .site-header{
    position:fixed;inset:0 auto 0 0;width:var(--rail-w);
    display:flex;flex-direction:column;gap:22px;
    padding:34px 26px 26px;
    overflow-y:auto;
    border-bottom:0;border-right:1px solid var(--line);
    background:linear-gradient(196deg,#0B2545 0%,#071A33 66%,#061E39 100%);
    box-shadow:none;
  }
  .site-header__top{flex-direction:column;align-items:flex-start;gap:18px;padding:0}
  .nav-toggle{display:none}
  .nav{
    position:static;opacity:1;visibility:visible;transform:none;
    display:flex;flex-direction:column;gap:20px;
    padding:0;background:none;border:0;box-shadow:none;
    max-height:none;overflow:visible;transition:none;
  }
  .nav__link{padding:9px 12px;font-size:14.5px}
  .rail-note{
    display:flex;margin-top:auto;padding-top:18px;border-top:1px solid var(--line);
  }
  .scroll-progress{left:var(--rail-w)}
  .footer__grid{grid-template-columns:minmax(260px,1.5fr) repeat(3,minmax(140px,1fr))}
}

/* ============ 14. Reveal ============ */
.reveal-ready [data-reveal]{
  opacity:0;transform:translateY(16px);
  transition:opacity .5s var(--ease),transform .5s var(--ease);
}
.reveal-ready [data-reveal].is-visible{opacity:1;transform:none}

/* ============ 15. 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;
    transition-delay:0ms!important;
  }
  .trace::after{animation:none;transform:none;width:100%;opacity:.45}
  .reveal-ready [data-reveal]{opacity:1;transform:none}
  .nav{transition:none}
}