:root {
  --paper: #f3efe4;
  --paper-2: #eae4d4;
  --ink: #1d2024;
  --muted: #5d5f5e;
  --rule: #cfc7b3;
  --grid: rgba(190, 88, 62, 0.13);
  --signal: #c8321c;
  --late: #c8321c;
  --short: #2a5d8f;
  --shape: #8a6a12;
  --ml: #1d2024;
  --gutter: clamp(16px, 5vw, 72px);
  --sans: "IBM Plex Sans KR", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
  --mono: "IBM Plex Mono", "SF Mono", Consolas, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.75;
  word-break: keep-all;
  overflow-wrap: break-word;
}

h1, h2, h3, p, ol, ul, dl, dd, figure { margin: 0; padding: 0; }
ol, ul { list-style: none; }
a { color: inherit; }
a:focus-visible { outline: 2px solid var(--signal); outline-offset: 3px; }

.top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 24px;
  padding: 20px var(--gutter);
  border-bottom: 1px solid var(--ink);
}
.brand { font-family: var(--mono); font-size: 13px; font-weight: 500; letter-spacing: 0.08em; }
.top nav { display: flex; gap: 24px; font-size: 14px; }
.top nav a { text-decoration: none; }
.top nav a:hover { color: var(--signal); }

.kicker { font-family: var(--mono); font-size: 13px; color: var(--signal); letter-spacing: 0.04em; }

.hero { padding: clamp(48px, 9vw, 112px) var(--gutter) clamp(36px, 5vw, 64px); }
.hero h1 {
  margin-top: 16px;
  font-size: clamp(32px, 6vw, 72px);
  line-height: 1.22;
  letter-spacing: -0.03em;
  font-weight: 700;
}
.lead { margin-top: 24px; max-width: 40em; color: var(--muted); font-size: clamp(16px, 1.6vw, 19px); }
.cta {
  display: inline-block;
  margin-top: 32px;
  padding: 12px 22px;
  background: var(--ink);
  color: var(--paper);
  font-weight: 500;
  text-decoration: none;
}
.cta:hover { background: var(--signal); }

.strip {
  border-block: 1px solid var(--ink);
  background-color: var(--paper-2);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 24px 24px;
}
.strip svg { display: block; width: 100%; height: clamp(210px, 22vw, 340px); }
.strip figcaption {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 8px var(--gutter);
  border-top: 1px solid var(--rule);
  font-family: var(--mono);
  font-size: 12px;
}
.strip figcaption span { color: var(--muted); font-family: var(--sans); }

.trace { fill: none; stroke: var(--ink); stroke-width: 1; vector-effect: non-scaling-stroke; }
.trace-flag { fill: none; stroke: var(--signal); stroke-width: 1.2; vector-effect: non-scaling-stroke; }
.band { fill: var(--signal); opacity: 0.1; }
.tick { stroke: var(--ink); stroke-width: 1; vector-effect: non-scaling-stroke; }
.tick-flag { stroke: var(--signal); }
.note { fill: var(--signal); font-family: var(--sans); font-size: 17px; font-weight: 700; }
.note-num { fill: var(--signal); font-family: var(--mono); font-size: 14px; }

@media (prefers-reduced-motion: no-preference) {
  .draw { stroke-dasharray: 1; stroke-dashoffset: 1; animation: pen 2.4s cubic-bezier(.4, 0, .3, 1) forwards; }
  .late-in { opacity: 0; animation: appear .4s 1.5s forwards; }
  @keyframes pen { to { stroke-dashoffset: 0; } }
  @keyframes appear { to { opacity: 1; } }
}

.spec dl { display: grid; grid-template-columns: repeat(4, 1fr); border-bottom: 1px solid var(--ink); }
.spec dl > div { padding: 22px var(--gutter); border-left: 1px solid var(--rule); }
.spec dl > div:first-child { border-left: 0; }
.spec dt { font-size: 13px; color: var(--muted); }
.spec dd { font-family: var(--mono); font-size: clamp(24px, 3vw, 38px); font-weight: 500; line-height: 1.3; letter-spacing: -0.02em; }
.spec small { margin-left: 4px; font-family: var(--sans); font-size: 13px; font-weight: 400; letter-spacing: 0; }

main > section:not(.hero, .spec) { padding: clamp(56px, 8vw, 104px) var(--gutter); }

main h2 { font-size: clamp(24px, 3.4vw, 40px); line-height: 1.32; letter-spacing: -0.02em; font-weight: 700; }

.why h2 { max-width: 20em; }
.cols { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; max-width: 980px; margin: 28px 0 0 auto; color: var(--muted); }

.how { border-top: 1px solid var(--ink); }
.how ol { display: grid; grid-template-columns: repeat(4, 1fr); margin-top: 40px; border-top: 1px solid var(--ink); }
.how li { padding: 20px 24px 8px 0; }
.how li + li { padding-left: 24px; border-left: 1px solid var(--rule); }
.n { font-family: var(--mono); font-size: 13px; color: var(--signal); }
.how h3 { margin-top: 8px; font-size: 20px; }
.how li p { margin-top: 8px; color: var(--muted); font-size: 16px; }

.detect { background: var(--paper-2); border-block: 1px solid var(--ink); }
.detect table { width: 100%; margin-top: 32px; border-collapse: collapse; font-size: 16px; }
.detect th, .detect td { padding: 14px 16px 14px 0; border-bottom: 1px solid var(--rule); text-align: left; vertical-align: top; }
.detect thead th { font-family: var(--mono); font-size: 12px; font-weight: 500; color: var(--muted); border-bottom-color: var(--ink); }
.detect tbody th { font-weight: 700; white-space: nowrap; }
.detect i { display: inline-block; width: 18px; height: 3px; margin: 0 10px 5px 0; }
.c-late { background: var(--late); }
.c-short { background: var(--short); }
.c-shape { background: var(--shape); }
.c-ml { background: var(--ml); }

.ml { display: grid; grid-template-columns: 3fr 2fr; gap: 56px; align-items: end; }
.ml h2 { margin-top: 12px; }
.ml > p { color: var(--muted); }

.screens { border-top: 1px solid var(--ink); }
.screens ul { margin-top: 28px; }
.screens li { display: grid; grid-template-columns: 180px 1fr; gap: 16px; padding: 14px 0; border-bottom: 1px solid var(--rule); color: var(--muted); }
.screens b { color: var(--ink); }

.security { background: var(--ink); color: var(--paper); }
.security p { margin-top: 18px; max-width: 42em; color: #c9c5b8; }

.contact h2 { max-width: 20em; }
.contact p { margin-top: 16px; color: var(--muted); max-width: 40em; }

footer { padding: 20px var(--gutter); border-top: 1px solid var(--ink); font-size: 13px; color: var(--muted); }

@media (max-width: 860px) {
  .top nav { display: none; }
  .spec dl { grid-template-columns: 1fr 1fr; }
  .spec dl > div { padding: 18px var(--gutter); border-bottom: 1px solid var(--rule); }
  .spec dl > div:nth-child(odd) { border-left: 0; }
  .cols, .ml { grid-template-columns: 1fr; gap: 20px; }
  .how ol { grid-template-columns: 1fr; }
  .how li, .how li + li { padding: 18px 0; border-left: 0; border-bottom: 1px solid var(--rule); }
  .detect table, .detect tbody, .detect tr, .detect tbody th, .detect td { display: block; }
  .detect thead { display: none; }
  .detect tr { padding: 14px 0; border-bottom: 1px solid var(--rule); }
  .detect tbody th, .detect td { padding: 0; border: 0; }
  .screens li { grid-template-columns: 1fr; gap: 0; }
}