:root{
  --ink:#1f1f1f;
  --paper:#ffffff;
  --ash:#f5f5f5;
  --line:#e3e3e3;
  --soft:#7c7c7c;
  --r:18px;
  --r-lg:24px;
  --pad:clamp(18px,3.2vw,28px);
}

*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  background:var(--ash);
  color:var(--ink);
  font-family:"Noto Sans KR",system-ui,-apple-system,"Segoe UI","Microsoft YaHei",sans-serif;
  font-size:17px;
  line-height:1.75;
  font-weight:400;
  overflow-x:hidden;
}
a{color:inherit}
img{max-width:100%;display:block}
menu{margin:0;padding:0;list-style:none}
a:focus-visible,summary:focus-visible{outline:2px solid var(--ink);outline-offset:3px;border-radius:12px}

/* 顶部细条 */
.stripe{
  display:flex;align-items:center;justify-content:space-between;gap:12px;
  background:var(--ink);color:#fff;
  font-size:15px;line-height:1.5;
  padding:6px max(16px,calc((100% - 1148px)/2));
}
.stripe-brand{letter-spacing:.22em;font-weight:500}
.stripe-dots{letter-spacing:.45em;color:#9a9a9a}

/* 顶部导航 */
.top{
  position:sticky;top:0;z-index:50;
  background:rgba(255,255,255,.93);
  border-bottom:1px solid var(--line);
  backdrop-filter:saturate(180%) blur(10px);
}
.bar{
  display:grid;grid-template-columns:1fr auto 1fr;align-items:center;gap:10px;
  max-width:1180px;margin:0 auto;padding:10px 16px;
}
.bar-l{justify-self:start}
.bar-r{justify-self:end}
.brand{
  justify-self:center;padding:6px 4px;
  font-size:1.15rem;font-weight:700;letter-spacing:.02em;
  text-decoration:none;white-space:nowrap;
}

.dd{position:relative}
.dd summary{
  list-style:none;display:inline-flex;align-items:center;gap:7px;
  min-height:44px;padding:0 14px;
  border:1px solid var(--line);border-radius:999px;background:var(--paper);
  font-size:15px;line-height:1.4;cursor:pointer;
  transition:background .2s ease,color .2s ease,border-color .2s ease;
}
.dd summary::-webkit-details-marker{display:none}
.dd summary::after{
  content:"";width:6px;height:6px;
  border-right:1.5px solid currentColor;border-bottom:1.5px solid currentColor;
  transform:translateY(-2px) rotate(45deg);
}
.dd[open] summary{background:var(--ink);border-color:var(--ink);color:#fff}
.dd menu{
  position:absolute;top:calc(100% + 10px);z-index:60;
  min-width:196px;padding:8px;
  background:var(--paper);border:1px solid var(--line);border-radius:var(--r);
  display:grid;gap:2px;
  animation:pop .18s ease both;
}
.dd-l menu{left:0}
.dd-r menu{right:0}
.dd menu a{
  display:flex;align-items:center;min-height:44px;padding:0 12px;
  border-radius:12px;text-decoration:none;font-size:16px;
}
.dd menu a:hover{background:var(--ash)}

/* 首屏 */
main{background:var(--ash)}
.hero{
  position:relative;overflow:hidden;
  max-width:1180px;margin:0 auto;min-height:70vh;
  display:grid;grid-template-columns:minmax(0,1.1fr) minmax(0,.9fr);
  align-items:center;gap:clamp(20px,4vw,56px);
  padding:clamp(36px,7vh,84px) var(--pad) clamp(36px,7vh,76px);
}
.hero-num{
  position:absolute;right:-2%;top:1%;z-index:0;
  font-size:clamp(130px,25vw,290px);font-weight:700;line-height:.78;
  letter-spacing:-.07em;color:#eaeaea;pointer-events:none;
}
.hero-txt{position:relative;z-index:1}
.hero h1{
  margin:0 0 18px;
  font-size:clamp(1.85rem,4.4vw,3.2rem);line-height:1.2;
  font-weight:700;letter-spacing:-.015em;
}
.lede{margin:0;max-width:36ch;color:var(--soft);font-size:17px}
.hero-fig{
  position:relative;z-index:1;margin:0;
  background:var(--paper);border:1px solid var(--line);border-radius:var(--r-lg);
  aspect-ratio:4/3;display:grid;place-items:center;overflow:hidden;
}
.hero-img{width:100%;height:100%;object-fit:cover}
.hero-blob{
  width:62%;aspect-ratio:1;border-radius:50%;
  background:radial-gradient(circle at 34% 28%,#2c2c2c,#1f1f1f 62%,#3d3d3d);
}

/* 主体：左侧目录 + 模块网格 */
.stage{
  max-width:1180px;margin:0 auto;
  padding:0 var(--pad) clamp(48px,8vw,80px);
  display:grid;grid-template-columns:240px minmax(0,1fr);
  gap:clamp(18px,3vw,30px);align-items:start;
}
.rail{
  position:sticky;top:88px;
  background:var(--paper);border:1px solid var(--line);border-radius:var(--r);
  padding:16px;
}
.rail-h{margin:0;font-size:1rem;font-weight:500;letter-spacing:.16em}
.rail hr,.foot hr{margin:10px 0 12px;border:0;border-top:1px solid var(--line)}
.rail-list{display:grid;gap:2px}
.rail-list a{
  display:flex;align-items:center;min-height:42px;padding:0 10px;
  border-radius:10px;text-decoration:none;font-size:16px;
  transition:background .18s ease;
}
.rail-list a:hover,.rail-list a[aria-current]{background:var(--ash)}
.rail-list a[aria-current]{font-weight:500}

.body{
  display:grid;grid-template-columns:repeat(4,minmax(0,1fr));
  gap:16px;align-items:start;min-width:0;
}
.body > article{
  grid-column:span 4;min-width:0;
  background:var(--paper);border:1px solid var(--line);border-radius:var(--r);
  padding:var(--pad);
  scroll-margin-top:96px;
  animation:rise .45s ease both;
}
.body > article:nth-child(4n+2),
.body > article:nth-child(4n+3){grid-column:span 2}
.body > article:nth-child(2){animation-delay:.05s}
.body > article:nth-child(3){animation-delay:.1s}
.body > article:nth-child(4){animation-delay:.14s}
.body > article:nth-child(5){animation-delay:.18s}
.body > article:nth-child(6){animation-delay:.22s}
.body > article:nth-child(7){animation-delay:.26s}
.body > article:target{outline:2px solid var(--ink);outline-offset:3px}

.body h2{
  margin:0 0 14px;
  font-size:clamp(1.15rem,2vw,1.45rem);line-height:1.35;
  letter-spacing:-.01em;font-weight:700;
}
.body h3{margin:22px 0 10px;font-size:1.05rem;line-height:1.45}
.body hr{margin:0 0 16px;border:0;border-top:1px solid var(--line)}
.body p{margin:0 0 14px}
.body p:last-child{margin-bottom:0}
.body ul,.body ol{margin:0 0 14px;padding-left:1.25em}
.body li{margin:0 0 6px}
.body a{text-decoration:underline;text-decoration-color:#c2c2c2;text-underline-offset:3px}
.body a:hover{text-decoration-color:var(--ink)}
.body figure{margin:0 0 14px}
.body figure img{width:100%;height:auto;border-radius:12px;border:1px solid var(--line)}
.body aside{
  margin:0 0 14px;padding:14px 16px;
  background:var(--ash);border-left:3px solid var(--ink);border-radius:12px;
  font-size:16px;
}
.body blockquote{
  margin:0 0 14px;padding:12px 16px;
  border-radius:12px;background:var(--ash);color:#3a3a3a;font-size:16px;
}
.body table{width:100%;border-collapse:collapse;font-size:16px}
.body th,.body td{border-bottom:1px solid var(--line);padding:8px 10px;text-align:left}

/* 页脚 */
.foot{
  background:var(--paper);border-top:1px solid var(--line);
  padding:clamp(32px,6vw,64px) max(16px,calc((100% - 1148px)/2)) 20px;
  display:grid;grid-template-columns:minmax(0,1.25fr) minmax(0,.75fr);
  gap:clamp(20px,4vw,40px);
}
.foot-mark{
  margin:0;font-size:clamp(2rem,5.6vw,4rem);font-weight:700;
  line-height:1;letter-spacing:-.03em;word-break:break-word;
}
.foot-h{margin:0;font-size:1rem;font-weight:500;letter-spacing:.16em}
.foot-list{display:grid;grid-template-columns:1fr 1fr;gap:2px}
.foot-list a{
  display:flex;align-items:center;min-height:42px;padding:0 8px;
  border-radius:10px;text-decoration:none;font-size:16px;
  transition:background .18s ease;
}
.foot-list a:hover{background:var(--ash)}
.foot-bottom{
  grid-column:1/-1;display:flex;align-items:center;justify-content:space-between;gap:16px;
  margin-top:clamp(16px,3vw,32px);padding-top:16px;
  border-top:1px solid var(--line);font-size:15px;
}
.foot-bottom p{margin:0;color:var(--soft)}
.foot-bottom a{
  display:inline-flex;align-items:center;min-height:44px;padding:0 14px;
  border:1px solid var(--line);border-radius:999px;
  text-decoration:none;font-size:15px;
}
.foot-bottom a:hover{background:var(--ash)}

@keyframes rise{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:none}}
@keyframes pop{from{opacity:0;transform:translateY(-4px)}to{opacity:1;transform:none}}

/* 移动端 */
@media (max-width:899px){
  body{font-size:17px}
  .stripe{font-size:15px}
  .bar{grid-template-columns:auto 1fr auto;padding:8px 12px;gap:8px}
  .brand{font-size:1.02rem;padding:8px 2px}
  .dd summary{padding:0 12px}
  .dd-l menu{left:0}
  .dd-r menu{right:0}

  .hero{
    grid-template-columns:1fr;min-height:0;
    padding:26px var(--pad) 32px;gap:20px;
  }
  .hero-num{font-size:clamp(120px,32vw,180px);top:auto;bottom:-6%;right:-4%}
  .hero h1{margin-bottom:12px}
  .hero-fig{aspect-ratio:16/10;border-radius:var(--r)}

  .stage{grid-template-columns:1fr;padding-bottom:44px}
  .rail{position:static}
  .rail-list{grid-template-columns:1fr 1fr}
  .rail-list a{min-height:44px}

  .body{grid-template-columns:minmax(0,1fr)}
  .body > article,
  .body > article:nth-child(4n+2),
  .body > article:nth-child(4n+3){grid-column:1/-1}

  .foot{grid-template-columns:1fr;gap:24px}
  .foot-list{grid-template-columns:1fr 1fr}
  .foot-bottom{flex-direction:column;align-items:flex-start;gap:10px}
}

@media (max-width:400px){
  .stripe-dots{display:none}
  .foot-bottom a{width:100%;justify-content:center}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *{animation:none!important;transition:none!important}
}

button[aria-expanded]{min-width:44px;min-height:44px}