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

:root{
  --ink-900:#0A1A2A;
  --ink-800:#122A42;
  --ink-700:#1A3856;
  --paper:#F5F2E8;
  --white:#FFFFFF;
  --gold:#C9A227;
  --gold-lt:#E8CF7A;
  --cinnabar:#B83B2C;
  --celadon:#6F9A8D;
  --silver:#A7B2BF;
  --charcoal:#121417;
  --line-dark:rgba(245,242,232,.14);
  --line-light:rgba(18,20,23,.14);
  --shadow-1:0 12px 28px -20px rgba(3,10,18,.9);
  --shadow-2:0 26px 50px -28px rgba(3,10,18,.95);
  --wrap:1240px;
  --gutter:clamp(1rem,4vw,3rem);
  --radius-s:4px;
  --radius-m:14px;
  --radius-l:28px;
  --font-head:"Songti SC","STSong","SimSun","Noto Serif CJK SC","Source Han Serif SC",serif;
  --font-body:system-ui,-apple-system,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  --font-num:ui-monospace,"SFMono-Regular","DIN Alternate",Consolas,"Liberation Mono",monospace;
  --dur:200ms;
  --ease:cubic-bezier(.2,.7,.3,1);
  --header-h:72px;
}

body{
  background:var(--ink-900);
  color:var(--paper);
  font-family:var(--font-body);
  font-size:1rem;
  line-height:1.75;
  letter-spacing:.01em;
  min-height:100vh;
  overflow-x:hidden;
  -webkit-font-smoothing:antialiased;
}

h1,h2,h3,h4{font-family:var(--font-head);font-weight:700;line-height:1.18;letter-spacing:-.005em;color:var(--paper)}
h1{font-size:clamp(2rem,4.6vw,3.5rem)}
h2{font-size:clamp(1.55rem,2.9vw,2.4rem)}
h3{font-size:clamp(1.15rem,1.7vw,1.45rem)}
h4{font-size:1.05rem}
strong{font-weight:700}
[id]{scroll-margin-top:calc(var(--header-h) + 28px)}

:focus-visible{outline:2px solid var(--gold-lt);outline-offset:3px;border-radius:2px}
:focus:not(:focus-visible){outline:none}

/* ---------- skip link ---------- */
.skip-link{
  position:fixed;top:.6rem;left:.9rem;z-index:300;
  padding:.6rem 1.1rem;
  background:var(--gold);color:#0d1722;
  font-size:.85rem;font-weight:700;letter-spacing:.06em;
  border-radius:var(--radius-s);
  box-shadow:var(--shadow-2);
  transform:translateY(-160%);
  transition:transform 180ms var(--ease);
}
.skip-link:focus-visible,.skip-link:focus{transform:translateY(0);outline-offset:2px}

/* ---------- header ---------- */
.site-header{
  position:sticky;top:0;z-index:120;
  background:linear-gradient(180deg,rgba(10,26,42,.86),rgba(10,26,42,.18) 70%,rgba(10,26,42,0));
  border-bottom:1px solid transparent;
  transition:background 220ms var(--ease),border-color 220ms var(--ease),box-shadow 220ms var(--ease);
}
.site-header[data-scrolled]{
  background:rgba(10,26,42,.97);
  border-bottom-color:var(--line-dark);
  box-shadow:0 20px 44px -34px #000;
  backdrop-filter:blur(10px);
}
.header-inner{
  width:100%;max-width:var(--wrap);margin-inline:auto;
  padding:.7rem var(--gutter);
  display:flex;align-items:center;gap:clamp(.75rem,2vw,2rem);
  min-height:var(--header-h);
}

.brand{display:flex;align-items:center;gap:.7rem;flex:0 0 auto}
.brand-mark{
  position:relative;flex:0 0 44px;
  display:grid;place-items:center;width:44px;height:44px;
  border:1px solid rgba(201,162,39,.55);
  background:linear-gradient(160deg,rgba(201,162,39,.18),rgba(10,26,42,0));
  color:var(--gold-lt);
  font-family:var(--font-num);font-size:.72rem;font-weight:700;letter-spacing:.14em;
  transition:border-color 180ms var(--ease);
}
.brand-mark::after{content:"";position:absolute;top:-3px;right:-3px;width:6px;height:6px;background:var(--cinnabar)}
.brand:hover .brand-mark{border-color:var(--gold-lt)}
.brand-text{display:flex;flex-direction:column;line-height:1.15}
.brand-name{font-family:var(--font-head);font-size:1.16rem;font-weight:700;color:var(--paper);letter-spacing:.03em}
.brand-note{font-size:.66rem;letter-spacing:.3em;color:var(--silver);text-transform:uppercase}

.nav{display:flex;margin-left:auto}
.nav-list{display:flex;align-items:center;gap:clamp(.15rem,1.1vw,1rem)}
.nav-item{position:relative}
.nav-link{
  position:relative;display:inline-block;
  padding:.55rem .5rem;
  font-size:.92rem;letter-spacing:.05em;color:var(--paper);
  transition:color 180ms var(--ease);
}
.nav-link::after{
  content:"";position:absolute;left:.5rem;right:.5rem;bottom:.3rem;height:1px;
  background:var(--gold);transform:scaleX(0);transform-origin:left;
  transition:transform 200ms var(--ease);
}
.nav-link:hover{color:var(--gold-lt)}
.nav-link:hover::after{transform:scaleX(1)}
.nav-link[aria-current="page"]{color:var(--gold-lt)}
.nav-link[aria-current="page"]::after{transform:scaleX(1);background:var(--gold-lt)}
.nav-link[aria-current="page"]::before{
  content:"";position:absolute;top:-1px;left:50%;transform:translateX(-50%);
  width:4px;height:4px;border-radius:50%;background:var(--cinnabar);
}

.header-actions{display:flex;align-items:center;gap:.6rem;flex:0 0 auto}
.header-cta{letter-spacing:.07em;white-space:nowrap}

.nav-toggle{
  display:none;width:44px;height:44px;
  place-items:center;position:relative;
  border:1px solid var(--line-dark);border-radius:2px;
  transition:border-color 180ms var(--ease),background 180ms var(--ease);
}
.nav-toggle:hover{border-color:rgba(232,207,122,.6)}
.nav-toggle-bar{position:relative;width:22px;height:2px;background:var(--paper);transition:background 160ms var(--ease)}
.nav-toggle-bar::before,.nav-toggle-bar::after{
  content:"";position:absolute;left:0;width:22px;height:2px;background:var(--paper);
  transition:transform 180ms var(--ease);
}
.nav-toggle-bar::before{top:-7px}
.nav-toggle-bar::after{top:7px}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar{background:transparent}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar::before{transform:translateY(7px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle-bar::after{transform:translateY(-7px) rotate(-45deg)}

.progress-rail{height:2px;background:rgba(245,242,232,.08);overflow:hidden}
.progress-bar{
  display:block;height:100%;width:0;
  background:linear-gradient(90deg,var(--gold),var(--gold-lt) 60%,var(--cinnabar));
  transition:width 120ms linear;
}

/* ---------- buttons ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:.5rem;
  padding:.62rem 1.1rem;border:1px solid transparent;border-radius:999px;
  font-size:.9rem;font-weight:600;letter-spacing:.05em;
  transition:background 180ms var(--ease),color 180ms var(--ease),border-color 180ms var(--ease),transform 180ms var(--ease);
}
.btn--gold{background:var(--gold);color:#0d1722;box-shadow:0 12px 26px -18px rgba(201,162,39,.95)}
.btn--gold:hover{background:var(--gold-lt)}
.btn--ghost{border-color:rgba(245,242,232,.28);color:var(--paper)}
.btn--ghost:hover{border-color:var(--gold-lt);color:var(--gold-lt)}
.btn--paper{background:var(--paper);color:var(--charcoal)}
.btn--paper:hover{background:var(--white)}
.btn--sm{padding:.42rem .82rem;font-size:.8rem}
.btn--block{width:100%}

/* ---------- footer ---------- */
.site-footer{position:relative;background:var(--ink-900);color:var(--silver);border-top:1px solid var(--line-dark)}
.site-footer::before{content:"";display:block;height:3px;background:linear-gradient(90deg,var(--gold),var(--cinnabar) 42%,rgba(201,162,39,0))}
.footer-inner{max-width:var(--wrap);margin-inline:auto;padding:clamp(2.25rem,5vw,4rem) var(--gutter) 1.5rem}
.footer-top{
  display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.9fr);
  gap:clamp(2rem,4vw,3.5rem);align-items:start;
}
.footer-brand{display:block}
.footer-mark{
  display:inline-grid;place-items:center;margin-bottom:1rem;
  padding:.32rem .62rem;border:1px solid rgba(201,162,39,.5);
  color:var(--gold-lt);font-family:var(--font-num);font-size:.76rem;letter-spacing:.18em;
}
.footer-slogan{font-family:var(--font-head);font-size:clamp(1.25rem,2vw,1.65rem);color:var(--paper);letter-spacing:.03em;line-height:1.3;margin-bottom:.6rem}
.footer-desc{font-size:.86rem;line-height:1.8;color:var(--silver);max-width:36ch}
.footer-stamp{
  margin-top:1.15rem;padding-top:.9rem;border-top:1px dashed rgba(245,242,232,.16);
  font-size:.72rem;letter-spacing:.18em;color:rgba(167,178,191,.8);
}
.footer-stamp-code{font-family:var(--font-num);color:var(--gold-lt);letter-spacing:.1em}

.footer-columns{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:clamp(1.25rem,2.4vw,2rem)}
.footer-col{min-width:0}
.footer-heading{
  display:flex;align-items:center;gap:.5rem;
  font-family:var(--font-head);font-size:.92rem;letter-spacing:.14em;color:var(--paper);
  padding-bottom:.6rem;margin-bottom:.9rem;border-bottom:1px solid var(--line-dark);
}
.footer-heading::before{content:"";width:14px;height:2px;background:var(--gold);flex:0 0 auto}
.footer-list{display:grid;gap:.5rem}
.footer-link{font-size:.9rem;color:var(--silver);transition:color 160ms var(--ease),padding-left 160ms var(--ease)}
.footer-link:hover{color:var(--gold-lt);padding-left:.28rem}
.footer-link[aria-current="page"]{color:var(--gold-lt)}

.footer-contact{display:grid;gap:1rem}
.contact-row{display:grid;gap:.18rem;justify-items:start}
.contact-label{font-size:.66rem;letter-spacing:.26em;color:var(--gold);text-transform:uppercase}
.contact-value{font-size:.9rem;line-height:1.7;color:var(--paper);word-break:break-word}
.contact-note{font-size:.76rem;line-height:1.7;color:rgba(167,178,191,.86);max-width:30ch}
.copy-btn{
  margin-top:.15rem;padding:.2rem .55rem;
  border:1px solid rgba(245,242,232,.22);border-radius:var(--radius-s);
  font-size:.72rem;letter-spacing:.08em;color:var(--silver);
  transition:color 160ms var(--ease),border-color 160ms var(--ease);
}
.copy-btn:hover{border-color:var(--gold-lt);color:var(--gold-lt)}
.copy-btn.is-copied{border-color:var(--celadon);color:var(--celadon)}
.copy-hint{font-size:.7rem;letter-spacing:.08em;color:var(--celadon);min-height:1em}

.footer-meta{
  display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:.5rem 1.5rem;
  margin-top:clamp(2rem,4vw,3rem);padding-top:1.25rem;
  border-top:1px solid rgba(245,242,232,.12);
  font-size:.76rem;letter-spacing:.05em;color:var(--silver);
}
.meta-item{max-width:52ch}
.meta-icp{font-family:var(--font-num);letter-spacing:.04em;color:var(--gold-lt)}

/* ---------- layout utilities ---------- */
.wrap{width:100%;max-width:var(--wrap);margin-inline:auto;padding-inline:var(--gutter)}
.band{position:relative;padding-block:clamp(2.5rem,6vw,5rem)}
.band--ink{background:var(--ink-800)}
.band--paper{background:var(--paper);color:var(--charcoal)}
.band--paper h2,.band--paper h3,.band--paper h4{color:var(--charcoal)}

.grid-12{display:grid;grid-template-columns:repeat(12,minmax(0,1fr));gap:clamp(1rem,2vw,1.75rem)}
.col-3{grid-column:span 3}
.col-4{grid-column:span 4}
.col-5{grid-column:span 5}
.col-6{grid-column:span 6}
.col-7{grid-column:span 7}
.col-8{grid-column:span 8}
.col-9{grid-column:span 9}
.col-12{grid-column:span 12}

.panel{
  position:relative;
  background:var(--ink-800);
  border:1px solid rgba(245,242,232,.12);
  border-radius:var(--radius-m);
  padding:clamp(1.1rem,2.2vw,1.9rem);
  transition:border-color 180ms var(--ease),box-shadow 200ms var(--ease),transform 200ms var(--ease);
}
.panel:hover{border-color:rgba(232,207,122,.45);box-shadow:var(--shadow-2)}
.panel--paper{background:var(--white);border-color:rgba(18,20,23,.1);color:var(--charcoal)}
.panel--paper h2,.panel--paper h3,.panel--paper h4{color:var(--charcoal)}

.kicker{display:block;font-size:.7rem;letter-spacing:.3em;text-transform:uppercase;color:var(--gold);margin-bottom:.5rem}
.index-num{
  display:block;font-family:var(--font-num);
  font-size:clamp(2.2rem,5vw,3.6rem);line-height:1;letter-spacing:-.02em;
  color:var(--gold);margin-bottom:.45rem;
}
.lede{font-size:1.05rem;line-height:1.8;color:rgba(245,242,232,.8);max-width:62ch}
.rule{height:1px;border:0;background:var(--line-dark);margin-block:clamp(1.4rem,3vw,2.4rem)}
.rule--gold{height:2px;background:linear-gradient(90deg,var(--gold),rgba(201,162,39,0))}

.tag-list{display:flex;flex-wrap:wrap;gap:.4rem}
.tag{
  display:inline-flex;align-items:center;gap:.35rem;
  padding:.18rem .55rem;border:1px solid currentColor;border-radius:2px;
  font-size:.72rem;letter-spacing:.08em;line-height:1.6;
}
.tag--gold{color:var(--gold-lt);background:rgba(201,162,39,.12);border-color:rgba(232,207,122,.5)}
.tag--celadon{color:var(--celadon);background:rgba(111,154,141,.14);border-color:rgba(111,154,141,.62)}
.tag--cinnabar{color:var(--white);background:var(--cinnabar);border-color:transparent}

/* ---------- breadcrumb ---------- */
.breadcrumb{display:flex;flex-wrap:wrap;align-items:center;gap:.45rem;font-size:.78rem;letter-spacing:.07em;color:var(--silver)}
.breadcrumb-item{display:inline-flex;align-items:center;gap:.45rem}
.breadcrumb-item + .breadcrumb-item::before{content:"/";color:rgba(167,178,191,.5)}
.breadcrumb-link{color:var(--silver);transition:color 160ms var(--ease)}
.breadcrumb-link:hover{color:var(--gold-lt)}
.breadcrumb-current{color:var(--paper)}

/* ---------- prose ---------- */
.prose{font-size:1.02rem;line-height:1.8;color:rgba(245,242,232,.86)}
.prose p{max-width:68ch}
.prose p + p{margin-top:.9rem}
.prose a{color:var(--gold-lt);text-decoration:underline;text-underline-offset:3px}
.prose ul,.prose ol{margin-block:.9rem;padding-left:1.25rem;max-width:66ch}
.prose li{margin-block:.35rem}
.prose ul li{list-style:disc}
.prose ol li{list-style:decimal}

/* ---------- toc ---------- */
.toc-link{
  display:flex;align-items:baseline;gap:.6rem;
  padding:.45rem 0;font-size:.85rem;color:var(--silver);
  border-bottom:1px solid rgba(245,242,232,.08);
  transition:color 160ms var(--ease);
}
.toc-link:hover{color:var(--gold-lt)}
.toc-link[aria-current="true"]{color:var(--gold-lt)}
.toc-num{font-family:var(--font-num);font-size:.76rem;color:var(--gold);flex:0 0 auto}

/* ---------- figures ---------- */
.figure{display:grid;gap:.65rem;margin:0}
.figure-frame{
  position:relative;overflow:hidden;
  border:1px solid rgba(245,242,232,.14);border-radius:var(--radius-m);
  background:linear-gradient(150deg,var(--ink-800),#0d2133);
  aspect-ratio:16/10;
}
.figure-frame img{width:100%;height:100%;object-fit:cover}
.figure-frame--wide{aspect-ratio:21/9}
.figure-frame--tall{aspect-ratio:3/4}
.figure-frame--square{aspect-ratio:1/1}
.figure-tag{position:absolute;top:.7rem;left:.7rem;z-index:1}
.figure-caption{display:flex;gap:.55rem;font-size:.78rem;line-height:1.65;color:var(--silver)}
.figure-num{font-family:var(--font-num);color:var(--gold);flex:0 0 auto}

/* ---------- tables ---------- */
.table-scroll{overflow-x:auto;border:1px solid var(--line-dark);border-radius:var(--radius-s);background:var(--white)}
.data-table{font-size:.9rem;color:var(--charcoal);min-width:640px}
.data-table caption{
  padding:.75rem 1rem;text-align:left;
  font-size:.78rem;letter-spacing:.14em;color:var(--charcoal);
  background:var(--paper);
}
.data-table th,.data-table td{padding:.65rem .85rem;text-align:left;vertical-align:top;border-bottom:1px solid rgba(18,20,23,.12)}
.data-table thead th{background:var(--paper);font-family:var(--font-head);letter-spacing:.06em}
.data-table tbody tr:last-child td{border-bottom:0}

/* ---------- responsive ---------- */
@media (max-width:1100px){
  .footer-top{grid-template-columns:minmax(0,1fr)}
  .footer-desc{max-width:52ch}
}
@media (max-width:1024px){
  .col-3,.col-4,.col-5{grid-column:span 6}
  .col-7,.col-8,.col-9{grid-column:span 12}
  .footer-columns{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media (max-width:980px){
  .nav{
    position:absolute;left:0;right:0;top:100%;
    display:none;margin:0;
    padding:1rem var(--gutter) 1.4rem;
    background:var(--ink-900);
    border-top:1px solid var(--line-dark);
    border-bottom:1px solid var(--line-dark);
    box-shadow:var(--shadow-2);
  }
  .nav[data-open]{display:block}
  .nav-list{flex-direction:column;align-items:stretch;gap:0}
  .nav-link{display:block;padding:.8rem .2rem;font-size:1rem;border-bottom:1px solid rgba(245,242,232,.1)}
  .nav-link::after{left:.2rem;right:auto;bottom:.55rem;width:26px}
  .nav-link[aria-current="page"]::before{left:.2rem;top:auto;bottom:-1px;transform:none;width:26px;height:2px;border-radius:0}
  .nav-toggle{display:grid}
  .header-inner{flex-wrap:wrap}
  .brand-note{letter-spacing:.22em}
}
@media (max-width:720px){
  :root{--header-h:64px}
  .header-cta{display:none}
  .footer-columns{grid-template-columns:minmax(0,1fr)}
  .col-6{grid-column:span 12}
  .footer-meta{justify-content:flex-start}
  .figure-frame{aspect-ratio:4/3}
  .figure-frame--wide{aspect-ratio:16/9}
}
@media (max-width:640px){
  .col-3,.col-4,.col-5,.col-6{grid-column:span 12}
  .brand-name{font-size:1.05rem}
  .footer-slogan{font-size:1.2rem}
  .contact-note{max-width:none}
}

@media (prefers-reduced-motion:no-preference){
  .panel:hover{transform:translateY(-2px)}
  .btn--gold:hover{transform:translateY(-1px)}
}
@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;
  }
  .panel:hover,.btn:hover{transform:none}
  .skip-link{transition:none}
}