:root{
  --hh:64px;
  --ink:#1f1f1f;
  --paper:#ffffff;
  --mist:#f5f5f5;
  --dim:#5d5d5d;
  --r:10px;
  --e1:0 1px 2px rgba(31,31,31,.07);
  --e2:0 6px 18px -8px rgba(31,31,31,.18),0 2px 6px rgba(31,31,31,.05);
  --e3:0 18px 38px -16px rgba(31,31,31,.26),0 4px 12px rgba(31,31,31,.07);
  --e4:0 34px 60px -24px rgba(31,31,31,.34),0 10px 22px rgba(31,31,31,.09);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  background:var(--mist);
  color:var(--ink);
  font-family:'Noto Sans KR',system-ui,-apple-system,'Segoe UI','Microsoft YaHei',sans-serif;
  font-size:16px;
  line-height:1.75;
  letter-spacing:.01em;
  overflow-x:hidden;
}
body::before{
  content:"";
  position:fixed;
  inset:0 0 auto 0;
  height:70vh;
  z-index:0;
  pointer-events:none;
  background:radial-gradient(120% 70% at 50% 0%,#fff 0%,rgba(255,255,255,0) 62%);
}
img{max-width:100%;height:auto;display:block}
a{color:var(--ink)}
main,header,footer,.rail{position:relative}

/* 顶栏 */
.top{
  position:sticky;
  top:0;
  z-index:40;
  display:flex;
  align-items:center;
  gap:10px;
  min-height:var(--hh);
  padding:10px 16px;
  background:rgba(255,255,255,.84);
  -webkit-backdrop-filter:blur(16px) saturate(1.3);
  backdrop-filter:blur(16px) saturate(1.3);
  box-shadow:var(--e2);
}
.logo{
  flex:0 0 auto;
  display:grid;
  place-items:center;
  width:44px;
  height:44px;
  overflow:hidden;
  border-radius:12px;
  background:var(--paper);
  box-shadow:var(--e2);
  text-decoration:none;
  color:var(--ink);
}
.logo img{width:100%;height:100%;object-fit:cover}
.logo-text{font-size:11px;line-height:1.1;font-weight:700;text-align:center;letter-spacing:-.02em;padding:0 3px}
.nav{margin-left:auto;display:flex;align-items:center}
.menu{position:relative}
.menu>summary{
  list-style:none;
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 15px;
  border-radius:999px;
  background:var(--paper);
  box-shadow:var(--e1);
  font-size:15px;
  font-weight:500;
  cursor:pointer;
}
.menu>summary::-webkit-details-marker{display:none}
.menu>summary::after{
  content:"";
  width:6px;height:6px;
  margin-left:8px;
  border-right:1.6px solid currentColor;
  border-bottom:1.6px solid currentColor;
  transform:rotate(45deg) translateY(-2px);
  transition:transform .2s ease;
}
.menu[open]>summary::after{transform:rotate(-135deg) translateY(-2px)}
.menu[open]>summary{box-shadow:var(--e3)}
.menu-list{
  position:absolute;
  right:0;
  top:calc(100% + 10px);
  z-index:6;
  min-width:220px;
  margin:0;
  padding:8px;
  list-style:none;
  border-radius:16px;
  background:rgba(255,255,255,.96);
  -webkit-backdrop-filter:blur(18px);
  backdrop-filter:blur(18px);
  box-shadow:var(--e4);
}
.menu:not([open])>.menu-list{display:none}
.menu-list li{margin:0}
.menu-list a{
  display:flex;
  align-items:center;
  min-height:44px;
  padding:0 12px;
  border-radius:8px;
  font-size:15px;
  text-decoration:none;
}
.menu-list a:hover,.menu-list a:focus-visible{background:var(--mist)}
.contact{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 16px;
  border-radius:999px;
  background:var(--ink);
  color:#fff;
  font-size:15px;
  text-decoration:none;
  box-shadow:var(--e2);
}

/* 二级锚点条 */
.rail{
  position:sticky;
  top:var(--hh);
  z-index:30;
  background:rgba(245,245,245,.9);
  -webkit-backdrop-filter:blur(12px);
  backdrop-filter:blur(12px);
  box-shadow:var(--e1);
}
.rail-bar{
  position:absolute;
  left:0;bottom:0;
  width:100%;height:2px;
  background:var(--ink);
  transform:scaleX(0);
  transform-origin:0 50%;
  transition:transform .15s linear;
}
.rail-track{
  display:flex;
  gap:8px;
  padding:9px 14px;
  overflow-x:auto;
  scrollbar-width:none;
  -webkit-overflow-scrolling:touch;
}
.rail-track::-webkit-scrollbar{display:none}
.rail-track a{
  flex:0 0 auto;
  display:inline-flex;
  align-items:center;
  min-height:40px;
  padding:0 14px;
  border-radius:999px;
  background:var(--paper);
  box-shadow:var(--e1);
  font-size:13.5px;
  color:var(--dim);
  text-decoration:none;
  white-space:nowrap;
}
.rail-track a:hover{color:var(--ink);box-shadow:var(--e2)}

/* 首屏 */
.hero{
  position:relative;
  z-index:1;
  display:grid;
  grid-template-columns:minmax(0,1fr);
  gap:26px;
  padding:30px 18px 34px;
  background:linear-gradient(180deg,#fff 0%,rgba(245,245,245,0) 100%);
  overflow:hidden;
}
.hero-copy{position:relative;z-index:2}
.tag{
  display:inline-block;
  margin:0 0 16px;
  padding:6px 13px;
  border-radius:999px;
  background:var(--paper);
  box-shadow:var(--e3);
  font-size:13px;
  font-weight:500;
  letter-spacing:.03em;
}
.hero h1{
  margin:0 0 16px;
  font-size:clamp(28px,7vw,46px);
  line-height:1.24;
  font-weight:700;
  letter-spacing:-.025em;
}
.hero-desc{
  max-width:54ch;
  margin:0 0 22px;
  color:#4a4a4a;
  font-size:16.5px;
  line-height:1.8;
}
.hero-act{margin:0}
.btn{
  display:inline-flex;
  align-items:center;
  min-height:46px;
  padding:0 24px;
  border-radius:999px;
  background:var(--ink);
  color:#fff;
  font-size:15px;
  font-weight:500;
  text-decoration:none;
  box-shadow:var(--e3);
}
.btn:hover{box-shadow:var(--e4)}
.hero-figure{
  position:relative;
  z-index:2;
  justify-self:center;
  width:min(280px,80%);
  min-height:172px;
  aspect-ratio:1;
  margin:0;
  display:grid;
  place-items:center;
  overflow:visible;
  border-radius:24px;
  background:var(--paper);
  box-shadow:var(--e4);
}
.hero-img{
  width:100%;height:100%;
  padding:18px;
  border-radius:24px;
  object-fit:contain;
}
.float-tag{
  position:absolute;
  left:-12px;
  bottom:-12px;
  padding:7px 14px;
  border-radius:999px;
  background:var(--paper);
  box-shadow:var(--e3);
  font-size:13px;
  font-weight:500;
  white-space:nowrap;
}

/* 主体 */
.shell{
  position:relative;
  z-index:1;
  display:grid;
  grid-template-columns:minmax(0,1fr);
  gap:24px;
  max-width:1120px;
  margin:0 auto;
  padding:24px 16px 52px;
}
.body{min-width:0}
.body>section{
  position:relative;
  z-index:1;
  margin:0 0 20px;
  padding:24px 20px;
  border-radius:var(--r);
  background:var(--paper);
  box-shadow:var(--e2);
  scroll-margin-top:132px;
}
.body>section:nth-child(1){z-index:9}
.body>section:nth-child(2){z-index:8}
.body>section:nth-child(3){z-index:7}
.body>section:nth-child(4){z-index:6}
.body>section:nth-child(5){z-index:5}
.body>section:nth-child(6){z-index:4}
.body>section:nth-child(7){z-index:3}
.body>section:nth-child(8){z-index:2}
.body h2{
  margin:0 0 6px;
  font-size:clamp(21px,3.2vw,27px);
  line-height:1.35;
  font-weight:700;
  letter-spacing:-.02em;
}
.body h3{margin:26px 0 6px;font-size:18px;line-height:1.5}
.body hr{
  height:1px;
  margin:0 0 20px;
  border:0;
  background:linear-gradient(90deg,var(--ink) 0%,rgba(31,31,31,.06) 70%);
}
.body p{margin:0 0 15px;line-height:1.85;color:#333}
.body a{text-underline-offset:3px;text-decoration-thickness:1px}
.body ul,.body ol{margin:0 0 16px;padding-left:1.3em}
.body li{margin:0 0 8px;line-height:1.72}
.body figure{margin:0 0 18px}
.body img{border-radius:var(--r)}
.body blockquote{
  margin:0 0 18px;
  padding:14px 18px;
  border-radius:var(--r);
  background:var(--mist);
  box-shadow:var(--e2);
  color:#3a3a3a;
}
.body table{width:100%;border-collapse:collapse;font-size:15px;margin:0 0 18px}
.body th,.body td{padding:10px 12px;text-align:left;border-bottom:1px solid #ececec}

/* 侧栏 */
.side{order:-1;min-width:0}
.side-card{
  padding:16px;
  border-radius:var(--r);
  background:var(--paper);
  box-shadow:var(--e3);
}
.side-card h2{margin:0 0 6px;font-size:16px;letter-spacing:.02em}
.side-card hr{
  height:1px;
  margin:0 0 12px;
  border:0;
  background:linear-gradient(90deg,var(--ink) 0%,rgba(31,31,31,.06) 80%);
}
.toc{
  list-style:none;
  counter-reset:toc;
  margin:0 0 10px;
  padding:0;
}
.toc li{counter-increment:toc;margin:0}
.toc a{
  display:flex;
  align-items:center;
  gap:10px;
  min-height:44px;
  padding:0 8px;
  border-radius:8px;
  font-size:14.5px;
  line-height:1.4;
  color:#3f3f3f;
  text-decoration:none;
}
.toc a::before{
  content:counter(toc,decimal-leading-zero);
  font-size:12px;
  color:#a3a3a3;
  font-variant-numeric:tabular-nums;
}
.toc a:hover{background:var(--mist);color:var(--ink)}
.to-top{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 8px;
  font-size:14px;
  color:var(--dim);
  text-decoration:none;
}

/* 页脚 */
.foot{
  position:relative;
  z-index:2;
  margin-top:12px;
  padding:38px 18px 26px;
  background:var(--paper);
  box-shadow:0 -22px 44px -34px rgba(31,31,31,.55);
}
.foot-main{
  display:grid;
  grid-template-columns:minmax(0,1fr);
  gap:30px;
  max-width:1120px;
  margin:0 auto;
}
.foot-brand{min-width:0}
.foot-logo{
  display:inline-grid;
  place-items:center;
  width:44px;height:44px;
  overflow:hidden;
  border-radius:12px;
  background:var(--mist);
  box-shadow:var(--e1);
  text-decoration:none;
  color:var(--ink);
}
.foot-logo img{width:100%;height:100%;object-fit:cover}
.foot-desc{margin:14px 0 0;font-size:14.5px;line-height:1.7;color:#4f4f4f;max-width:46ch}
.foot-address{
  display:flex;
  flex-direction:column;
  gap:2px;
  margin:14px 0 0;
  font-style:normal;
  font-size:14px;
  color:var(--dim);
}
.foot-col h2{margin:0 0 6px;font-size:16px;letter-spacing:.02em}
.foot-col hr{
  height:1px;
  margin:0 0 12px;
  border:0;
  background:linear-gradient(90deg,var(--ink) 0%,rgba(31,31,31,.06) 80%);
}
.foot-col ul{
  list-style:none;
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:2px;
  margin:0;
  padding:0;
}
.foot-col a{
  display:flex;
  align-items:center;
  min-height:44px;
  padding:0 8px;
  border-radius:8px;
  font-size:14.5px;
  color:#3a3a3a;
  text-decoration:none;
}
.foot-col a:hover{background:var(--mist);color:var(--ink)}
.foot-sub{
  display:flex;
  justify-content:center;
  max-width:1120px;
  margin:28px auto 0;
}
.sub{
  display:flex;
  gap:8px;
  width:100%;
  max-width:420px;
  padding:8px;
  border-radius:14px;
  background:var(--mist);
  box-shadow:var(--e1);
}
.sub-in{
  flex:1;
  min-width:0;
  min-height:44px;
  padding:0 14px;
  border:0;
  border-radius:var(--r);
  background:var(--paper);
  box-shadow:var(--e1);
  font:inherit;
  font-size:15px;
  color:var(--ink);
}
.sub-in:focus{outline:2px solid var(--ink);outline-offset:1px}
.sub-btn{
  min-height:44px;
  padding:0 20px;
  border:0;
  border-radius:var(--r);
  background:var(--ink);
  color:#fff;
  font:inherit;
  font-size:15px;
  cursor:pointer;
  box-shadow:var(--e2);
}
.foot-end{
  max-width:1120px;
  margin:26px auto 0;
  padding-top:16px;
  border-top:1px solid #ededed;
  text-align:center;
  font-size:13px;
  color:#7a7a7a;
}

/* 动效 */
.reveal{opacity:0;transform:translateY(22px)}
.reveal.in{
  opacity:1;
  transform:none;
  transition:opacity .6s ease,transform .7s cubic-bezier(.2,.7,.2,1);
}

@media (min-width:760px){
  .top{padding:10px 24px}
  .hero{padding:44px 32px 46px}
  .shell{padding:32px 24px 64px}
  .body>section{padding:34px 34px}
  .body>section:nth-child(even){margin-left:26px}
  .body>section:nth-child(3n){margin-right:24px}
  .body>section+section{margin-top:-8px}
  .foot{padding:48px 32px 30px}
  .foot-main{grid-template-columns:minmax(0,1.15fr) minmax(0,1fr);gap:44px}
}

@media (min-width:820px){
  .hero{
    grid-template-columns:minmax(0,1.4fr) minmax(0,.6fr);
    align-items:center;
    min-height:45vh;
  }
  .hero-figure{width:min(300px,100%)}
}

@media (min-width:900px){
  .menu>summary{display:none}
  .menu:not([open])>.menu-list,.menu-list{
    display:flex;
    position:static;
    gap:2px;
    min-width:0;
    padding:4px;
    border-radius:999px;
    background:var(--paper);
    -webkit-backdrop-filter:none;
    backdrop-filter:none;
    box-shadow:var(--e1);
  }
  .menu-list a{padding:0 12px;font-size:14.5px;border-radius:999px}
  .shell{
    grid-template-columns:minmax(0,1fr) 268px;
    gap:34px;
    padding:34px 24px 76px;
    align-items:start;
  }
  .side{order:0;position:sticky;top:calc(var(--hh) + 58px)}
}

@media (min-width:1100px){
  .hero{padding:54px 48px 52px}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal{opacity:1;transform:none;transition:none}
  .rail-bar{transition:none}
  .hero-figure{transform:none !important}
}

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