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

:root{
  --indigo-900:#0E1B33;
  --indigo-700:#17284A;
  --sand:#F4EBDD;
  --sand-hi:#FBF6EC;
  --crimson:#B23A48;
  --crimson-soft:#D96C6C;
  --turquoise:#2E8B84;
  --turquoise-soft:#7CC9BE;
  --gold:#C9A227;
  --mist:#C8D2E0;

  --bg:var(--sand);
  --bg-deep:var(--sand-hi);
  --band:#E9DDC9;
  --surface:var(--sand-hi);
  --surface-2:#EFE3D0;
  --ink:var(--indigo-900);
  --ink-soft:#4C5566;
  --ink-mute:#6D7585;
  --line:rgba(23,40,74,.16);
  --line-strong:rgba(23,40,74,.32);
  --link:#1F6E68;
  --step:var(--crimson);
  --gold-ink:#806515;
  --focus:var(--crimson);
  --shadow-1:0 1px 0 rgba(14,27,51,.05),0 10px 26px -20px rgba(14,27,51,.55);

  --font-display:"Noto Serif SC","Source Han Serif SC","Songti SC",Georgia,serif;
  --font-body:"Noto Sans SC","PingFang SC","Microsoft YaHei",system-ui,sans-serif;
  --font-num:"DIN Alternate","Inter",ui-monospace,"SFMono-Regular",monospace;
  --shell:1280px;
  --gutter:clamp(16px,4vw,40px);
  --radius:2px;
}

[data-theme="night"]{
  --bg:var(--indigo-900);
  --bg-deep:#0A1528;
  --band:var(--indigo-700);
  --surface:var(--indigo-700);
  --surface-2:#1E3157;
  --ink:var(--sand);
  --ink-soft:rgba(244,235,221,.8);
  --ink-mute:rgba(200,210,224,.72);
  --line:rgba(200,210,224,.2);
  --line-strong:rgba(200,210,224,.4);
  --link:var(--turquoise-soft);
  --step:#E29AA0;
  --gold-ink:#E2C56A;
  --focus:var(--gold);
  --shadow-1:0 12px 34px -24px rgba(0,0,0,.95);
}

body{
  background:var(--bg);
  color:var(--ink);
  font-family:var(--font-body);
  font-size:1rem;
  font-weight:400;
  line-height:1.75;
  -webkit-font-smoothing:antialiased;
  transition:background-color .2s ease,color .2s ease;
}
::selection{background:var(--gold);color:#0E1B33}
h1,h2,h3,h4{line-height:1.25;font-weight:700}
.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}

.shell{width:100%;max-width:var(--shell);margin-inline:auto;padding-inline:var(--gutter)}

/* ---------- skip link ---------- */
.skip-link{
  position:absolute;left:var(--gutter);top:-120px;z-index:200;
  display:inline-flex;align-items:center;min-height:44px;padding:0 18px;
  background:var(--crimson);color:#fff;font-size:.875rem;border-radius:var(--radius);
  transition:top .16s ease;
}
.skip-link:focus{top:12px}

/* ---------- header ---------- */
.site-header{position:sticky;top:0;z-index:90;background:var(--bg);border-bottom:1px solid var(--line)}
.header-top{border-bottom:1px solid var(--line)}
.header-top__inner{display:flex;align-items:center;gap:24px;min-height:76px}

.brand{display:inline-flex;align-items:center;gap:12px;flex:none}
.brand__mark{
  position:relative;display:grid;place-items:center;width:42px;height:42px;
  background:linear-gradient(155deg,#1C3157,var(--indigo-900));
  color:var(--sand-hi);font-family:var(--font-display);font-size:1.3rem;line-height:1;
  border:1px solid rgba(200,210,224,.28);border-radius:var(--radius);
  box-shadow:inset 0 1px 0 rgba(251,246,236,.16);
}
.brand__mark::after{content:"";position:absolute;left:8px;right:8px;bottom:5px;height:2px;background:var(--crimson)}
.brand__text{display:grid;gap:2px}
.brand__name{font-family:var(--font-display);font-size:1.3rem;font-weight:700;letter-spacing:.08em;line-height:1.2}
.brand__tagline{font-size:.75rem;letter-spacing:.18em;color:var(--ink-mute);line-height:1.4}

.header-note{display:flex;align-items:center;gap:10px;flex:1 1 auto;min-width:0;padding-left:20px;border-left:1px solid var(--line);font-size:.8125rem;color:var(--ink-soft)}
.header-note__dot{flex:none;width:6px;height:6px;border-radius:50%;background:var(--crimson);box-shadow:0 0 0 3px rgba(178,58,72,.16)}
.header-note__text{overflow:hidden;text-overflow:ellipsis;white-space:nowrap}

.header-tools{display:flex;align-items:center;gap:8px;flex:none}
.tool-link{padding:7px 10px;font-size:.8125rem;color:var(--ink-soft);border-radius:var(--radius);border-bottom:1px solid transparent;transition:color .12s ease,border-color .12s ease,background-color .12s ease}
.tool-link:hover{color:var(--link);border-bottom-color:var(--link)}

.theme-toggle{display:inline-flex;align-items:center;gap:8px;padding:7px 12px;border:1px solid var(--line-strong);border-radius:999px;font-size:.75rem;letter-spacing:.1em;color:var(--ink-soft);transition:border-color .12s ease,color .12s ease,transform .12s ease}
.theme-toggle:hover{border-color:var(--turquoise);color:var(--link);transform:translateY(-2px)}
.theme-toggle__icon{width:11px;height:11px;border-radius:50%;background:linear-gradient(140deg,var(--gold),var(--crimson));transition:background .2s ease}
[data-theme="night"] .theme-toggle__icon{background:linear-gradient(140deg,var(--turquoise-soft),var(--sand))}
.theme-toggle__label{font-family:var(--font-num);letter-spacing:.14em}

.nav-toggle{display:none;align-items:center;gap:9px;padding:8px 14px;border:1px solid var(--line-strong);border-radius:999px;font-size:.8125rem;color:var(--ink)}
.nav-toggle__bars{position:relative;display:block;width:16px;height:10px;flex:none}
.nav-toggle__bars::before,.nav-toggle__bars::after{content:"";position:absolute;left:0;width:100%;height:1.5px;background:currentColor;transition:transform .16s ease,top .16s ease,bottom .16s ease}
.nav-toggle__bars::before{top:1px}
.nav-toggle__bars::after{bottom:1px}
.nav-toggle__label{letter-spacing:.08em}
.site-header[data-open] .nav-toggle__bars::before{top:4px;transform:rotate(45deg)}
.site-header[data-open] .nav-toggle__bars::after{bottom:5px;transform:rotate(-45deg)}
.site-header[data-open] .nav-toggle{border-color:var(--crimson);color:var(--crimson)}

.header-band{background:var(--band);border-bottom:1px solid var(--line);position:relative}
.site-nav{display:block}
.site-nav__list{position:relative;display:flex;align-items:stretch;flex-wrap:wrap}
.site-nav__list::before{content:"";position:absolute;left:0;right:0;top:50%;height:1px;background:var(--line-strong)}
.site-nav__item{position:relative}
.site-nav__link{
  position:relative;display:inline-flex;align-items:baseline;gap:8px;
  padding:15px 20px;background:var(--band);color:var(--ink);
  font-size:.9375rem;letter-spacing:.02em;
  transition:background-color .12s ease,color .12s ease,transform .12s ease;
}
.site-nav__num{font-family:var(--font-num);font-size:.6875rem;letter-spacing:.14em;color:var(--step);font-variant-numeric:tabular-nums}
.site-nav__label{line-height:1.4}
.site-nav__link:hover{background:var(--surface);color:var(--link);transform:translateY(-2px)}
.site-nav__link[aria-current="page"]{font-weight:500;color:var(--ink)}
.site-nav__link[aria-current="page"] .site-nav__num{color:var(--crimson)}
.site-nav__link[aria-current="page"]::after{content:"";position:absolute;left:20px;right:20px;bottom:0;height:2px;background:var(--crimson)}

.read-progress{position:absolute;left:0;right:0;bottom:-1px;height:2px;background:rgba(200,210,224,.28);pointer-events:none}
.read-progress__bar{display:block;width:100%;height:100%;transform:scaleX(0);transform-origin:0 50%;background:linear-gradient(90deg,var(--turquoise),var(--gold) 55%,var(--crimson));transition:transform .1s linear}

/* ---------- footer ---------- */
.site-footer{
  position:relative;overflow:hidden;
  margin-top:clamp(56px,8vw,104px);
  background:linear-gradient(180deg,#0E1B33 0%,#0B1730 62%,#0A1528 100%);
  color:var(--sand);
}
.site-footer::before{
  content:"";position:absolute;inset:0;pointer-events:none;
  background:
    radial-gradient(120% 90% at 88% -12%,rgba(201,162,39,.2),transparent 62%),
    radial-gradient(90% 70% at 0% 0%,rgba(46,139,132,.18),transparent 58%);
}
.footer-flags{position:relative;display:flex;gap:6px;height:4px}
.footer-flags span{flex:1;display:block;height:100%;transform-origin:0 50%;animation:flag-sway 6s ease-in-out infinite}
.footer-flags span:nth-child(1){background:var(--crimson)}
.footer-flags span:nth-child(2){background:var(--gold);animation-delay:.4s}
.footer-flags span:nth-child(3){background:var(--turquoise);animation-delay:.8s}
.footer-flags span:nth-child(4){background:var(--crimson-soft);animation-delay:1.2s}
.footer-flags span:nth-child(5){background:var(--sand);animation-delay:1.6s}
@keyframes flag-sway{0%,100%{transform:rotate(0deg)}50%{transform:rotate(1.6deg)}}

.footer__inner{position:relative;padding-top:clamp(40px,6vw,72px)}
.footer__main{display:grid;grid-template-columns:minmax(0,1.25fr) minmax(0,.62fr) minmax(0,.72fr) minmax(0,1fr);gap:40px 32px;padding-bottom:48px;border-bottom:1px solid rgba(200,210,224,.18)}
.footer__brand{font-family:var(--font-display);font-size:1.5rem;letter-spacing:.1em;line-height:1.3}
.footer__tagline{margin-top:10px;font-size:.75rem;letter-spacing:.22em;color:var(--gold)}
.footer__summary{margin-top:18px;max-width:34em;font-size:.875rem;line-height:1.8;color:rgba(244,235,221,.74)}

.footer-col__title{font-size:.6875rem;font-weight:500;letter-spacing:.24em;color:var(--gold);margin-bottom:16px}
.footer-col__list{display:grid;gap:10px}
.footer-link{display:inline-block;padding-bottom:2px;font-size:.9375rem;color:rgba(244,235,221,.84);border-bottom:1px solid transparent;transition:color .12s ease,border-color .12s ease}
.footer-link:hover{color:var(--turquoise-soft);border-bottom-color:var(--turquoise-soft)}

.footer__contact{display:grid;gap:18px;align-content:start}
.contact-item{display:grid;gap:6px}
.contact-item__label{font-size:.6875rem;letter-spacing:.22em;color:rgba(200,210,224,.72)}
.contact-item__value{font-family:var(--font-num);font-size:.9375rem;letter-spacing:.03em;color:var(--sand);font-variant-numeric:tabular-nums}
.contact-item__value--text{font-family:var(--font-body);font-size:.875rem;line-height:1.7;letter-spacing:.01em}

.copy-email{display:inline-flex;align-items:center;gap:10px;justify-self:start;padding:7px 12px;border:1px solid rgba(200,210,224,.3);border-radius:999px;color:var(--sand);transition:border-color .12s ease,color .12s ease}
.copy-email:hover{border-color:var(--turquoise-soft);color:var(--turquoise-soft)}
.copy-email__text{font-family:var(--font-num);font-size:.8125rem;letter-spacing:.02em}
.copy-email__hint{font-size:.6875rem;letter-spacing:.14em;color:var(--gold)}
.copy-email__status{min-height:1.2em;font-size:.75rem;color:var(--turquoise-soft)}

.footer__note{max-width:60em;padding:24px 0 4px;font-size:.75rem;line-height:1.8;color:rgba(200,210,224,.62)}
.footer__bottom{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:14px 28px;padding:22px 0 34px}
.footer__legal{display:flex;flex-wrap:wrap;gap:8px 22px}
.footer__legal-link{font-size:.8125rem;color:rgba(244,235,221,.72);border-bottom:1px solid transparent;transition:color .12s ease,border-color .12s ease}
.footer__legal-link:hover{color:var(--turquoise-soft);border-bottom-color:var(--turquoise-soft)}
.footer__meta{font-size:.75rem;letter-spacing:.04em;color:rgba(200,210,224,.64)}
.footer__icp{font-family:var(--font-num);letter-spacing:.06em;color:rgba(244,235,221,.8)}

/* ---------- shared layout ---------- */
.content{width:100%;max-width:var(--shell);margin-inline:auto;padding:clamp(24px,5vw,64px) var(--gutter)}
.prose{max-width:42em;font-size:1rem;line-height:1.75;color:var(--ink)}
.prose p+p{margin-top:1em}
.prose h2{font-family:var(--font-display);font-size:clamp(1.6rem,2.6vw,2.2rem);margin:1.6em 0 .6em;letter-spacing:.01em}
.prose h3{font-family:var(--font-display);font-size:1.25rem;margin:1.4em 0 .5em;letter-spacing:.02em}
.prose a{color:var(--link);text-decoration:underline;text-decoration-thickness:1px;text-underline-offset:3px}
.prose ul{display:grid;gap:.5em;margin:1em 0}
.prose li{position:relative;padding-left:1.2em}
.prose li::before{content:"";position:absolute;left:0;top:.72em;width:9px;height:1px;background:var(--crimson)}

.grid{display:grid;gap:24px}
.grid--12{grid-template-columns:repeat(12,minmax(0,1fr))}
.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}

/* ---------- buttons ---------- */
.btn{
  display:inline-flex;align-items:center;gap:10px;min-height:44px;padding:0 20px;
  border:1px solid var(--line-strong);border-radius:999px;background:transparent;
  font-size:.9375rem;font-weight:500;color:var(--ink);
  transition:transform .12s ease,border-color .12s ease,color .12s ease,background-color .12s ease;
}
.btn:hover{transform:translateY(-2px);border-color:var(--turquoise);color:var(--link)}
.btn--primary{background:var(--crimson);border-color:var(--crimson);color:#fff}
.btn--primary:hover{background:#9E2F3C;border-color:#9E2F3C;color:#fff}
.btn--ghost{background:var(--surface);border-color:var(--line)}

/* ---------- breadcrumb ---------- */
.breadcrumb{padding:14px 0;border-bottom:1px solid var(--line);font-size:.8125rem}
.breadcrumb__list{display:flex;flex-wrap:wrap;align-items:center;gap:6px}
.breadcrumb__item{display:inline-flex;align-items:center;gap:6px;color:var(--ink-mute)}
.breadcrumb__link{color:var(--ink-soft);border-bottom:1px solid transparent;transition:color .12s ease,border-color .12s ease}
.breadcrumb__link:hover{color:var(--link);border-bottom-color:var(--link)}
.breadcrumb__sep{color:var(--line-strong)}
.breadcrumb__current{color:var(--crimson);font-weight:500}

/* ---------- specimen card ---------- */
.specimen{
  position:relative;padding:24px;background:var(--surface);border:1px solid var(--line);
  border-radius:var(--radius);box-shadow:var(--shadow-1);
  transition:transform .12s ease,border-color .12s ease;
}
.specimen:hover{transform:translateY(-2px);border-color:var(--turquoise)}
.specimen__label{display:block;margin-bottom:10px;font-family:var(--font-num);font-size:.6875rem;letter-spacing:.2em;color:var(--step)}
.specimen__title{font-family:var(--font-display);font-size:1.25rem;line-height:1.4;margin-bottom:8px}
.specimen__body{font-size:.875rem;line-height:1.75;color:var(--ink-soft)}

/* ---------- step anchor ---------- */
.step-anchor{display:grid;grid-template-columns:auto minmax(0,1fr);gap:16px 20px;align-items:start;padding:22px 0;border-top:1px solid var(--line)}
.step-anchor__num{font-family:var(--font-num);font-size:clamp(2.6rem,5vw,4.6rem);line-height:.9;letter-spacing:-.02em;color:var(--step);font-variant-numeric:tabular-nums}
.step-anchor__title{font-family:var(--font-display);font-size:1.375rem;margin-bottom:6px}
.step-anchor__body{font-size:.9375rem;line-height:1.75;color:var(--ink-soft)}

/* ---------- index rail ---------- */
.index-rail{position:sticky;top:112px;display:grid;gap:2px;padding-left:16px;border-left:1px solid var(--line)}
.index-rail__link{
  display:flex;align-items:baseline;gap:10px;margin-left:-18px;padding:8px 0 8px 16px;
  font-size:.875rem;color:var(--ink-mute);border-left:2px solid transparent;
  transition:color .12s ease,border-color .12s ease;
}
.index-rail__link:hover{color:var(--ink)}
.index-rail__link.is-active{color:var(--crimson);border-left-color:var(--crimson);font-weight:500}

/* ---------- floating tag ---------- */
.floating-tag{
  display:inline-flex;align-items:center;gap:8px;padding:8px 14px;
  background:var(--surface-2);border:1px solid var(--line-strong);border-radius:999px;
  font-size:.75rem;letter-spacing:.08em;color:var(--ink-soft);box-shadow:var(--shadow-1);
}
.floating-tag::before{content:"";width:6px;height:6px;border-radius:50%;background:var(--turquoise);flex:none}

/* ---------- timeline ---------- */
.timeline{display:grid;padding-left:24px;border-left:1px solid var(--line)}
.timeline__item{position:relative;padding-bottom:28px}
.timeline__item::before{content:"";position:absolute;left:-29px;top:.4em;width:9px;height:9px;border-radius:50%;background:var(--gold);box-shadow:0 0 0 3px var(--bg)}
.timeline__time{display:block;margin-bottom:6px;font-family:var(--font-num);font-size:.75rem;letter-spacing:.14em;color:var(--gold-ink)}
.timeline__title{font-size:1rem;font-weight:500;margin-bottom:4px}
.timeline__body{font-size:.875rem;line-height:1.75;color:var(--ink-soft)}

/* ---------- dual column ---------- */
.dual-column{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:clamp(16px,3vw,40px)}
.dual-column>*{padding:24px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius)}

/* ---------- tag filter ---------- */
.tag-filter{display:flex;flex-wrap:wrap;gap:8px}
.tag-filter__item{
  padding:6px 14px;border:1px solid var(--line-strong);border-radius:999px;
  font-size:.8125rem;color:var(--ink-soft);background:transparent;
  transition:border-color .12s ease,color .12s ease,background-color .12s ease;
}
.tag-filter__item:hover{border-color:var(--turquoise);color:var(--link)}
.tag-filter__item[aria-pressed="true"]{background:var(--crimson);border-color:var(--crimson);color:#fff}

/* ---------- media containers ---------- */
.media{display:grid;gap:10px;margin:0}
.media__frame{position:relative;overflow:hidden;border:1px solid var(--line);border-radius:var(--radius);background:var(--surface-2);aspect-ratio:16/10}
.media__img{width:100%;height:100%;object-fit:cover}
.media__caption{font-size:.75rem;line-height:1.6;letter-spacing:.06em;color:var(--ink-mute)}
.media--wide .media__frame{aspect-ratio:21/9}
.media--tall .media__frame{aspect-ratio:4/5}
.media--flag .media__frame{
  background:
    repeating-linear-gradient(112deg,rgba(251,246,236,.22) 0 2px,transparent 2px 26px),
    linear-gradient(115deg,rgba(178,58,72,.92) 0 18%,rgba(201,162,39,.88) 18% 34%,rgba(46,139,132,.86) 34% 52%,rgba(23,40,74,.94) 52% 74%,rgba(217,108,108,.82) 74% 100%);
}
.media--light .media__frame{background:linear-gradient(150deg,#FBF6EC,#F4EBDD 44%,#EBD9B4 76%,#C9A227)}
.media--screen .media__frame{background:radial-gradient(120% 120% at 22% 0%,#2E8B84,#17284A 56%,#0E1B33)}

/* ---------- reveal protocol ---------- */
[data-reveal]{transition:opacity .22s ease,transform .22s ease}
html[data-motion="ready"] [data-reveal]{opacity:0;transform:translateY(8px)}
html[data-motion="ready"] [data-reveal].is-visible{opacity:1;transform:none}

/* ---------- tablet ---------- */
@media (max-width:1180px){
  .header-note{display:none}
}
@media (max-width:980px){
  .nav-toggle{display:inline-flex}
  .site-nav{display:none;padding:6px 0 18px}
  .site-header[data-open] .site-nav{display:block}
  .site-nav__list{display:block}
  .site-nav__list::before{display:none}
  .site-nav__item{border-bottom:1px solid var(--line)}
  .site-nav__item:last-child{border-bottom:0}
  .site-nav__link{display:flex;width:100%;padding:14px 4px;background:transparent}
  .site-nav__link:hover{transform:none;background:transparent}
  .site-nav__link[aria-current="page"]::after{left:4px;right:auto;width:28px;bottom:8px}
  .grid--12{grid-template-columns:repeat(8,minmax(0,1fr))}
  .span-4,.span-5{grid-column:span 4}
  .span-6{grid-column:span 4}
  .span-7,.span-8{grid-column:span 8}
  .index-rail{position:static;top:auto}
  .footer__main{grid-template-columns:minmax(0,1.2fr) minmax(0,1fr);gap:32px}
  .footer__contact{grid-column:1 / -1;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}
}
@media (max-width:720px){
  .tool-link{display:none}
  .header-top__inner{min-height:66px;gap:14px}
  .brand__mark{width:38px;height:38px;font-size:1.15rem}
  .brand__name{font-size:1.15rem}
}
@media (max-width:640px){
  .grid--12{grid-template-columns:repeat(4,minmax(0,1fr))}
  .span-4,.span-5,.span-6,.span-7,.span-8{grid-column:span 4}
  .dual-column{grid-template-columns:1fr}
  .footer__main{grid-template-columns:1fr;gap:28px;padding-bottom:36px}
  .footer__contact{grid-template-columns:1fr}
  .footer__bottom{flex-direction:column;align-items:flex-start}
  .step-anchor{grid-template-columns:minmax(0,1fr);gap:8px}
}
@media (max-width:560px){
  .brand__tagline{display:none}
  .theme-toggle__label{display:none}
  .theme-toggle{padding:8px 10px}
}

@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation-duration:.001ms !important;animation-iteration-count:1 !important;transition-duration:.001ms !important}
  .footer-flags span{animation:none}
  .read-progress__bar{transition:none}
  html[data-motion="ready"] [data-reveal]{opacity:1;transform:none}
  .site-nav__link:hover,.specimen:hover,.btn:hover,.theme-toggle:hover{transform:none}
}