/* ================= 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,figure,blockquote,dl,dd{margin:0}
ul,ol{padding:0;list-style:none}
img,svg,video{display:block;max-width:100%}
a{color:inherit;text-decoration:none}
button{font:inherit;color:inherit;background:none;border:0}
[hidden]{display:none!important}

/* ================= 02 tokens ================= */
:root{
  --night:#071C2E;
  --cabin:#0E3048;
  --lake:#1F6F9E;
  --dusk:#4B3A6B;
  --dusk-deep:#2A1E42;
  --cyan:#4EF0D0;
  --sand:#D8B46A;
  --paper:#F5F1E8;
  --ink:#101820;
  --haze:#9DB4C4;
  --grid:#20384A;

  --font-display:"Barlow Condensed","Oswald","Noto Sans SC","Source Han Sans SC",sans-serif;
  --font-body:"Noto Sans SC","Source Han Sans SC","PingFang SC","Microsoft YaHei",sans-serif;
  --font-mono:"IBM Plex Mono","Sarasa Mono SC","JetBrains Mono",monospace;

  --step-hero:clamp(3.2rem,8vw,8.5rem);
  --step-title:clamp(1.8rem,3.5vw,3.4rem);
  --step-body:clamp(.95rem,1.1vw,1.05rem);
  --step-label:.72rem;

  --topbar:64px;
  --rail:0px;
  --gutter:clamp(1.1rem,3vw,3.2rem);
  --maxw:1240px;
  --gap:clamp(1rem,2.4vw,2rem);
  --line:1px solid rgba(157,180,196,.16);
  --ease:cubic-bezier(.22,.61,.36,1);
}
@media (min-width:1024px){
  :root{--topbar:72px;--rail:clamp(150px,13vw,186px)}
}

/* ================= 03 base ================= */
body{
  min-height:100vh;
  padding-top:var(--topbar);
  padding-left:var(--rail);
  font-family:var(--font-body);
  font-size:var(--step-body);
  font-weight:400;
  line-height:1.75;
  color:rgba(245,241,232,.9);
  background-color:var(--night);
  background-image:
    repeating-radial-gradient(circle at 84% 6%,rgba(78,240,208,.05) 0 1px,transparent 1px 46px),
    repeating-linear-gradient(0deg,rgba(32,56,74,.5) 0 1px,transparent 1px 72px),
    repeating-linear-gradient(90deg,rgba(32,56,74,.5) 0 1px,transparent 1px 72px),
    radial-gradient(120% 80% at 80% -10%,rgba(75,58,107,.55),transparent 62%),
    radial-gradient(90% 60% at 6% 108%,rgba(31,111,158,.28),transparent 66%);
  overflow-x:hidden;
}
h1,h2,h3,h4{
  font-family:var(--font-display);
  font-weight:700;
  letter-spacing:-.02em;
  line-height:1.08;
  color:var(--paper);
}
::selection{background:var(--cyan);color:var(--ink)}
:focus-visible{outline:2px solid var(--cyan);outline-offset:3px}

/* ================= 04 utilities ================= */
.mono{font-family:var(--font-mono);font-weight:400;letter-spacing:.08em}
.visually-hidden{
  position:absolute!important;width:1px;height:1px;padding:0;margin:-1px;
  overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0
}
.eyebrow{
  display:inline-flex;align-items:center;gap:.6rem;
  font-family:var(--font-mono);font-size:var(--step-label);
  letter-spacing:.22em;text-transform:uppercase;color:var(--sand)
}
.eyebrow::before{content:"";width:26px;height:1px;background:var(--sand)}
.section-title{font-size:var(--step-title);color:var(--paper)}
.lede{font-size:clamp(1rem,1.5vw,1.25rem);line-height:1.7;color:rgba(245,241,232,.84);max-width:62ch}
.rule{height:1px;border:0;margin:0;background:linear-gradient(90deg,rgba(78,240,208,.55),rgba(157,180,196,.16) 42%,transparent)}

/* ================= 05 layout ================= */
.page-shell{
  width:100%;max-width:var(--maxw);margin:0 auto;
  padding:clamp(1.6rem,4vw,3.4rem) var(--gutter);
}
.prose{max-width:70ch;color:rgba(245,241,232,.86);line-height:1.75}
.prose p + p{margin-top:1em}
.prose a{color:var(--cyan);border-bottom:1px solid rgba(78,240,208,.4)}
.prose a:hover{border-bottom-color:var(--cyan)}
.prose h2,.prose h3{margin:1.8em 0 .6em;font-size:clamp(1.3rem,2.2vw,1.9rem)}
.grid{display:grid;gap:var(--gap)}
.grid-2{display:grid;gap:var(--gap);grid-template-columns:repeat(auto-fit,minmax(260px,1fr))}
.grid-3{display:grid;gap:var(--gap);grid-template-columns:repeat(auto-fit,minmax(220px,1fr))}
.grid-rail{display:grid;gap:var(--gap);grid-template-columns:1fr}
@media (min-width:900px){
  .grid-rail{grid-template-columns:minmax(0,4fr) minmax(0,8fr);gap:clamp(1.4rem,3.5vw,3.4rem)}
}

/* ================= 06 breadcrumb ================= */
.breadcrumb{
  display:flex;flex-wrap:wrap;align-items:center;gap:.5rem;
  font-family:var(--font-mono);font-size:.68rem;letter-spacing:.1em;
  color:var(--haze);margin-bottom:clamp(1rem,2.4vw,1.8rem)
}
.breadcrumb a{color:var(--haze);border-bottom:1px solid transparent;transition:color .18s,border-color .18s}
.breadcrumb a:hover{color:var(--cyan);border-bottom-color:var(--cyan)}
.breadcrumb .sep{color:rgba(157,180,196,.45)}
.breadcrumb [aria-current="page"]{color:var(--paper)}

/* ================= 07 buttons ================= */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:.45rem;
  min-height:44px;padding:.55rem 1.05rem;
  font-family:var(--font-mono);font-size:.74rem;letter-spacing:.1em;
  text-decoration:none;cursor:pointer;
  border:1px solid transparent;
  transition:color .18s,border-color .18s,background-color .18s,box-shadow .18s
}
.btn-solid{background:var(--cyan);color:var(--night);border-color:var(--cyan)}
.btn-solid:hover{background:#74f8df;box-shadow:0 0 0 4px rgba(78,240,208,.16)}
.btn-ghost{background:transparent;color:var(--paper);border-color:rgba(31,111,158,.9)}
.btn-ghost:hover{color:var(--cyan);border-color:var(--cyan);box-shadow:0 0 0 4px rgba(78,240,208,.12)}
.btn-sm{min-height:44px;padding:.3rem .75rem;font-size:.67rem}

/* ================= 08 tags & panels ================= */
.tag{
  display:inline-flex;align-items:center;gap:.35rem;
  font-family:var(--font-mono);font-size:.64rem;letter-spacing:.12em;
  text-transform:uppercase;padding:.22rem .5rem;
  border:1px solid rgba(157,180,196,.42);color:var(--haze)
}
.tag-accent{border-color:var(--cyan);color:var(--cyan)}
.tag-sand{border-color:var(--sand);color:var(--sand)}
.paper-panel{
  position:relative;
  background:var(--paper);color:var(--ink);
  padding:clamp(1.4rem,3vw,2.4rem);
  border:1px solid rgba(16,24,32,.14);
  box-shadow:10px 10px 0 rgba(75,58,107,.55)
}
.paper-panel h2,.paper-panel h3{color:var(--ink)}
.paper-panel .mono{letter-spacing:.12em}

/* ================= 09 media ================= */
.media{
  position:relative;display:block;overflow:hidden;
  aspect-ratio:16/9;
  background:
    linear-gradient(150deg,rgba(31,111,158,.38),rgba(75,58,107,.5));
  border:1px solid rgba(157,180,196,.22)
}
.media::before{
  content:"";position:absolute;inset:0;pointer-events:none;opacity:.65;
  background-image:
    repeating-linear-gradient(0deg,rgba(157,180,196,.16) 0 1px,transparent 1px 26px),
    repeating-linear-gradient(90deg,rgba(157,180,196,.16) 0 1px,transparent 1px 26px)
}
.media img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.media-16x9{aspect-ratio:16/9}
.media-4x3{aspect-ratio:4/3}
.media-1x1{aspect-ratio:1/1}
.media-3x4{aspect-ratio:3/4}
.media-caption{
  margin-top:.55rem;font-family:var(--font-mono);font-size:.66rem;
  letter-spacing:.1em;color:var(--haze)
}

/* ================= 10 filter ================= */
.filter-bar{display:flex;flex-wrap:wrap;gap:.5rem;align-items:center}
.filter-btn{
  min-height:44px;padding:.35rem .85rem;
  font-family:var(--font-mono);font-size:.68rem;letter-spacing:.1em;
  color:var(--haze);border:1px solid rgba(157,180,196,.34);
  cursor:pointer;transition:color .18s,border-color .18s,background-color .18s
}
.filter-btn:hover{color:var(--paper);border-color:var(--cyan)}
.filter-btn[aria-pressed="true"]{
  color:var(--cyan);border-color:var(--cyan);background:rgba(78,240,208,.12)
}

/* ================= 11 reveal ================= */
.js [data-reveal]{
  opacity:0;transform:translateY(16px);
  transition:opacity .55s var(--ease),transform .55s var(--ease)
}
.js [data-reveal].is-revealed{opacity:1;transform:none}

/* ================= 12 skip link ================= */
.skip-link{
  position:fixed;top:.6rem;left:.6rem;z-index:900;
  transform:translateY(-180%);
  padding:.7rem 1rem;background:var(--cyan);color:var(--night);
  font-family:var(--font-mono);font-size:.76rem;letter-spacing:.1em;
  transition:transform .2s var(--ease)
}
.skip-link:focus{transform:none}

/* ================= 13 header frame ================= */
.frame-top{
  position:fixed;top:0;left:var(--rail);right:0;height:var(--topbar);z-index:130;
  display:flex;align-items:center;gap:.75rem;
  padding:0 var(--gutter);
  background:linear-gradient(180deg,rgba(14,48,72,.97),rgba(9,32,52,.94));
  border-bottom:1px solid rgba(31,111,158,.6);
  backdrop-filter:blur(10px)
}
.brand{display:flex;align-items:center;gap:.7rem;min-width:0;color:var(--paper)}
.brand-mark{
  flex:none;width:9px;height:26px;border-radius:1px;
  background:var(--cyan);box-shadow:0 0 14px rgba(78,240,208,.75)
}
.brand-text{display:block;min-width:0}
.brand-name{
  display:block;
  font-family:var(--font-display);font-weight:700;
  font-size:clamp(1.02rem,1.5vw,1.3rem);letter-spacing:.01em;line-height:1.1
}
.brand-line{
  display:block;margin-top:2px;
  font-family:var(--font-mono);font-size:.63rem;letter-spacing:.14em;
  color:var(--haze);white-space:nowrap
}
.frame-meta{display:flex;align-items:center;gap:.55rem;margin-left:auto}
.edition-badge{
  display:inline-block;
  font-family:var(--font-mono);font-size:.66rem;letter-spacing:.1em;
  color:var(--ink);background:var(--sand);
  padding:.32rem .6rem;
  clip-path:polygon(0 0,100% 0,100% 72%,92% 100%,0 100%)
}
.frame-progress{
  position:fixed;top:var(--topbar);left:var(--rail);right:0;height:2px;z-index:126;
  background:rgba(32,56,74,.8);pointer-events:none
}
.frame-progress span{
  display:block;height:100%;width:100%;
  transform:scaleX(0);transform-origin:left center;
  background:linear-gradient(90deg,var(--cyan),rgba(78,240,208,.35));
  transition:transform .1s linear
}
.nav-toggle{
  display:none;align-items:center;gap:.5rem;margin-left:auto;
  min-height:44px;padding:.35rem .7rem;
  border:1px solid rgba(31,111,158,.75);background:rgba(7,28,46,.6);
  color:var(--paper);cursor:pointer;
  font-family:var(--font-mono);font-size:.68rem;letter-spacing:.12em
}
.nav-toggle-bars{display:grid;gap:4px;width:16px}
.nav-toggle-bars i{display:block;height:1px;background:var(--cyan);font-style:normal;transition:transform .2s var(--ease)}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars i:first-child{transform:translateY(2.5px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] .nav-toggle-bars i:last-child{transform:translateY(-2.5px) rotate(-45deg)}

/* ================= 14 index rail nav ================= */
.site-nav{
  position:fixed;top:0;left:0;bottom:0;width:var(--rail);z-index:120;
  overflow-y:auto;
  background:linear-gradient(180deg,rgba(7,28,46,.99),rgba(9,33,53,.97));
  border-right:1px solid rgba(32,56,74,.95)
}
.site-nav-inner{display:flex;flex-direction:column;min-height:100%;padding:0 .85rem 1.2rem}
.nav-eyebrow{
  display:flex;align-items:center;gap:.4rem;
  min-height:var(--topbar);margin:0 0 .3rem;
  font-size:.6rem;letter-spacing:.2em;color:var(--sand);
  text-transform:uppercase;
  border-bottom:1px solid rgba(157,180,196,.16)
}
.nav-eyebrow span{color:var(--haze);letter-spacing:.08em}
.nav-list{display:grid}
.nav-list li{border-top:1px solid rgba(157,180,196,.12)}
.nav-list li:first-child{border-top:0}
.nav-list a{
  position:relative;
  display:grid;grid-template-columns:1.55rem minmax(0,1fr);gap:.4rem;
  align-items:start;
  padding:.68rem .55rem .68rem .6rem;
  color:var(--haze);font-size:.76rem;line-height:1.4;
  transition:color .18s,background-color .18s
}
.nav-idx{
  font-family:var(--font-mono);font-size:.62rem;letter-spacing:.06em;
  color:rgba(157,180,196,.7);padding-top:.12em;font-weight:500
}
.nav-label{display:block}
.nav-list a:hover{color:var(--paper);background:linear-gradient(90deg,rgba(31,111,158,.32),transparent 88%)}
.nav-list a:hover .nav-idx{color:var(--cyan)}
.nav-list a[aria-current="page"]{
  color:var(--paper);
  background:linear-gradient(90deg,rgba(78,240,208,.15),transparent 85%);
  box-shadow:inset 2px 0 0 var(--cyan)
}
.nav-list a[aria-current="page"] .nav-idx{color:var(--cyan)}
.nav-foot{display:none}

/* ================= 15 responsive header ================= */
@media (max-width:1023.98px){
  .frame-meta{display:none}
  .nav-toggle{display:inline-flex}
  .site-nav{
    top:var(--topbar);bottom:auto;left:0;right:0;width:auto;
    max-height:calc(100dvh - var(--topbar));overflow-y:auto;
    background:var(--cabin);
    border-right:0;border-bottom:1px solid rgba(78,240,208,.4);
    box-shadow:0 26px 50px rgba(0,0,0,.55);
    opacity:0;visibility:hidden;transform:translateY(-10px);pointer-events:none;
    transition:opacity .22s var(--ease),transform .22s var(--ease),visibility .22s
  }
  .site-nav[data-open]{opacity:1;visibility:visible;transform:none;pointer-events:auto}
  .site-nav-inner{padding:0 0 1rem}
  .nav-eyebrow{
    min-height:0;padding:.8rem 1rem .4rem;margin:0;
    border-bottom:1px solid rgba(157,180,196,.16)
  }
  .nav-list a{
    grid-template-columns:2.1rem minmax(0,1fr);
    padding:.85rem 1rem;font-size:.95rem
  }
  .nav-idx{font-size:.68rem}
  .nav-foot{
    display:grid;gap:.55rem;
    margin-top:.9rem;padding:.9rem 1rem 0;
    border-top:1px solid rgba(157,180,196,.2)
  }
  .nav-foot .edition-badge{justify-self:start}
  .brand-line{display:none}
}

/* ================= 16 footer ================= */
.site-footer{
  position:relative;
  margin-top:clamp(3rem,8vw,7rem);
  background:var(--dusk-deep);
  border-top:1px solid rgba(216,180,106,.38);
  color:var(--paper)
}
.footer-inner{
  max-width:var(--maxw);margin:0 auto;
  padding:clamp(2.4rem,6vw,4.6rem) var(--gutter) clamp(1.6rem,3vw,2.6rem);
  display:grid;grid-template-columns:1fr;gap:clamp(1.8rem,4vw,3rem)
}
.footer-brand-name{
  font-family:var(--font-display);font-weight:700;
  font-size:clamp(1.6rem,3vw,2.4rem);letter-spacing:-.02em;line-height:1.05
}
.footer-summary{
  margin-top:.9rem;max-width:34ch;
  color:var(--haze);font-size:.9rem;line-height:1.75
}
.footer-edition{
  display:inline-block;margin-top:1.1rem;
  font-family:var(--font-mono);font-size:.64rem;letter-spacing:.16em;
  color:var(--ink);background:var(--sand);padding:.3rem .6rem;
  clip-path:polygon(0 0,100% 0,100% 100%,6px 100%,0 calc(100% - 6px))
}
.footer-nav{display:grid;grid-template-columns:1fr 1fr;gap:clamp(1.2rem,3vw,2.4rem)}
.footer-col-title{
  position:relative;
  font-family:var(--font-mono);font-size:.66rem;letter-spacing:.22em;
  text-transform:uppercase;color:var(--sand);
  margin:0 0 .9rem;padding-top:.85rem
}
.footer-col-title::before{content:"";position:absolute;top:0;left:0;width:22px;height:1px;background:var(--sand)}
.footer-col ul{display:grid;gap:.1rem}
.footer-col ul li a{
  display:inline-block;padding:.32rem 0;
  font-size:.92rem;color:rgba(245,241,232,.8);
  border-bottom:1px solid transparent;
  transition:color .18s,border-color .18s
}
.footer-col ul li a:hover{color:var(--cyan);border-bottom-color:rgba(78,240,208,.5)}
.footer-contact-list{display:grid}
.footer-contact-list li{
  display:grid;gap:.1rem;padding:.55rem 0;
  border-bottom:1px dashed rgba(157,180,196,.2)
}
.contact-key{
  font-family:var(--font-mono);font-size:.62rem;letter-spacing:.18em;
  text-transform:uppercase;color:var(--haze)
}
.contact-val{font-size:.86rem;color:var(--paper);word-break:break-all}
.footer-note{margin-top:.9rem;font-size:.78rem;line-height:1.7;color:var(--haze)}
.footer-base{
  max-width:var(--maxw);margin:0 auto;
  padding:1.1rem var(--gutter) 2rem;
  display:flex;flex-wrap:wrap;gap:.6rem 1.6rem;
  align-items:center;justify-content:space-between;
  border-top:1px solid rgba(157,180,196,.16);
  font-family:var(--font-mono);font-size:.68rem;letter-spacing:.08em;
  color:var(--haze)
}
.footer-icp{color:var(--haze)}

@media (min-width:720px){
  .footer-inner{grid-template-columns:1fr 1fr}
  .footer-brand{grid-column:1 / -1}
}
@media (min-width:1080px){
  .footer-inner{grid-template-columns:minmax(0,1.4fr) minmax(0,2fr) minmax(0,1.3fr)}
  .footer-brand{grid-column:auto}
}

/* ================= 17 motion preferences ================= */
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{
    animation-duration:.001ms!important;
    animation-iteration-count:1!important;
    transition-duration:.001ms!important
  }
  .js [data-reveal]{opacity:1;transform:none}
  .skip-link{transition:none}
}