:root {
  --paper: #ffffff;
  --ink: #161616;
  --muted: #666666;
  --soft: #f5f5f5;
  --line: #dedede;
  --max: 1120px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo", "Noto Sans KR", "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.75;
  letter-spacing: -0.01em;
}

a { color: inherit; text-decoration-thickness: 1px; text-underline-offset: 3px; }

code, pre { font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace; }

.wrap { width: min(calc(100% - 40px), var(--max)); margin: 0 auto; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgb(255 255 255 / 94%);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(10px);
}

.nav { display: flex; min-height: 58px; align-items: center; justify-content: space-between; gap: 20px; }
.brand { font-weight: 750; text-decoration: none; letter-spacing: -0.03em; }
.nav-links { display: flex; flex-wrap: wrap; gap: 16px; font-size: 14px; }
.nav-links a { color: var(--muted); text-decoration: none; }
.nav-links a:hover { color: var(--ink); }

.hero { padding: 100px 0 72px; border-bottom: 1px solid var(--line); }
.eyebrow { margin: 0 0 14px; color: var(--muted); font-size: 13px; font-weight: 700; letter-spacing: .04em; text-transform: uppercase; }
h1, h2, h3, p { margin-top: 0; }
h1 { max-width: 900px; margin-bottom: 22px; font-size: clamp(36px, 6vw, 66px); line-height: 1.2; letter-spacing: -0.055em; }
.mobile-space { display: none; }
h2 { font-size: clamp(27px, 3.6vw, 40px); line-height: 1.25; letter-spacing: -0.045em; }
h3 { margin-bottom: 8px; font-size: 19px; line-height: 1.4; letter-spacing: -0.025em; }
.lead { max-width: 760px; margin-bottom: 28px; color: #333; font-size: clamp(18px, 2vw, 22px); line-height: 1.7; }
.hero-actions, .inline-actions { display: flex; flex-wrap: wrap; gap: 10px; }
.button {
  display: inline-flex;
  min-height: 42px;
  align-items: center;
  justify-content: center;
  padding: 9px 15px;
  border: 1px solid var(--ink);
  background: var(--ink);
  color: #fff;
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
}
.button:hover { background: #333; }
.button.ghost { background: #fff; color: var(--ink); border-color: var(--line); }
.button.ghost:hover { background: var(--soft); }

section { padding: 80px 0; border-bottom: 1px solid var(--line); }
.summary-section { padding: 64px 0; }
.summary-section h2 { margin-bottom: 24px; }
.section-intro { max-width: 720px; margin-bottom: 34px; color: var(--muted); }
.grid { display: grid; gap: 16px; }
.grid.two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }

.card {
  padding: 23px;
  border: 1px solid var(--line);
  background: #fff;
}
.card p:last-child { margin-bottom: 0; }
.meta { margin: 0 0 10px; color: var(--muted); font-size: 13px; }
.small { color: var(--muted); font-size: 14px; }

.fact-grid { display: grid; grid-template-columns: .92fr 1fr 1.4fr 1.15fr; gap: 12px; }
.fact {
  display: flex;
  min-height: 144px;
  flex-direction: column;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--soft);
}
.fact strong {
  display: block;
  margin-top: auto;
  font-size: clamp(25px, 2vw, 30px);
  line-height: 1.17;
  letter-spacing: -0.045em;
  text-wrap: balance;
}
.fact span { color: var(--muted); font-size: 13px; }
.fact--qa strong small {
  display: block;
  margin-bottom: 5px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 650;
  line-height: 1.4;
  letter-spacing: -0.02em;
}
.fact--qa strong b {
  display: block;
  font-size: inherit;
  font-weight: inherit;
  line-height: inherit;
  letter-spacing: inherit;
  white-space: nowrap;
}

.timeline { width: 100%; margin: 0; padding: 0; border-top: 1px solid var(--line); list-style: none; }
.timeline > li {
  display: grid;
  grid-template-columns: 150px minmax(0, 1fr);
  gap: 34px;
  padding: 26px 0 30px;
  border-bottom: 1px solid var(--line);
}
.timeline > li:last-child { border-bottom: 0; }
.timeline time { padding-top: 4px; color: var(--muted); font-size: 14px; font-weight: 650; }
.timeline .role { min-width: 0; }
.timeline ul { margin: 10px 0 0; padding-left: 20px; }
.timeline ul li { display: list-item; padding: 0; }

.tag-list { display: flex; flex-wrap: wrap; gap: 8px; margin: 0; padding: 0; list-style: none; }
.tag { padding: 4px 9px; border: 1px solid var(--line); background: #fff; color: #444; font-size: 13px; line-height: 1.45; }

.case-study { display: grid; grid-template-columns: 135px 1fr; gap: 22px; padding: 28px 0; border-top: 1px solid var(--line); }
.case-study:first-child { border-top: 0; }
.case-label { color: var(--muted); font-size: 13px; font-weight: 700; }
.case-study p { margin-bottom: 10px; }
.case-study ul { margin: 8px 0 0; padding-left: 20px; }

.notice { padding: 18px 20px; border-left: 3px solid var(--ink); background: var(--soft); }
.notice p:last-child { margin-bottom: 0; }

.site-footer { padding: 34px 0 46px; color: var(--muted); font-size: 14px; }

/* Interview study page */
.study-hero { padding: 74px 0 46px; border-bottom: 1px solid var(--line); }
.study-hero h1 { max-width: 980px; font-size: clamp(34px, 5vw, 56px); }
.study-controls { display: grid; grid-template-columns: 1fr auto; gap: 12px; align-items: center; margin-top: 28px; }
.search {
  min-height: 45px;
  padding: 10px 13px;
  border: 1px solid var(--line);
  border-radius: 0;
  outline: none;
  color: var(--ink);
  font: inherit;
}
.search:focus { border-color: var(--ink); }
.filters { display: flex; flex-wrap: wrap; gap: 8px; }
.filter {
  min-height: 34px;
  padding: 6px 10px;
  border: 1px solid var(--line);
  background: #fff;
  color: var(--muted);
  cursor: pointer;
  font: inherit;
  font-size: 13px;
}
.filter[aria-pressed="true"], .filter:hover { border-color: var(--ink); color: var(--ink); }
.study-layout { display: grid; grid-template-columns: 238px minmax(0, 1fr); gap: 48px; padding: 56px 0 90px; }
.study-aside { position: sticky; top: 78px; align-self: start; }
.study-aside h2 { margin-bottom: 12px; font-size: 20px; }
.study-aside ol { margin: 0; padding-left: 20px; color: var(--muted); font-size: 14px; }
.study-aside li { margin-bottom: 8px; }
.tech-list { display: grid; gap: 14px; }
.tech-card { border: 1px solid var(--line); background: #fff; }
.tech-card[hidden] { display: none; }
.tech-card summary { display: flex; align-items: flex-start; justify-content: space-between; gap: 18px; padding: 20px; cursor: pointer; list-style: none; }
.tech-card summary::-webkit-details-marker { display: none; }
.tech-card summary::after { flex: 0 0 auto; color: var(--muted); content: "+"; font-size: 22px; line-height: 1; }
.tech-card[open] summary::after { content: "−"; }
.tech-title { display: block; font-size: 20px; font-weight: 750; letter-spacing: -0.03em; }
.tech-category { display: block; margin-top: 3px; color: var(--muted); font-size: 13px; }
.tech-content { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; padding: 0 20px 20px; }
.tech-box { padding: 15px; background: var(--soft); }
.tech-box h4 { margin: 0 0 7px; font-size: 13px; }
.tech-box p { margin: 0; font-size: 14px; }
.tech-full { grid-column: 1 / -1; }
pre { overflow-x: auto; margin: 0; padding: 15px; background: #181818; color: #f4f4f4; font-size: 12px; line-height: 1.6; white-space: pre-wrap; }
.copy-answer { margin-top: 8px; padding: 0; border: 0; border-bottom: 1px solid var(--ink); background: none; color: var(--ink); cursor: pointer; font: inherit; font-size: 13px; }

@media (max-width: 780px) {
  .wrap { width: min(calc(100% - 28px), var(--max)); }
  .nav { min-height: 54px; }
  .nav-links { display: none; }
  .hero { padding: 70px 0 54px; }
  .hero h1 {
    font-size: clamp(27px, 7.5vw, 30px);
    line-height: 1.27;
    word-break: keep-all;
  }
  .hero h1 br { display: none; }
  .mobile-space { display: inline; }
  .lead { font-size: 17px; word-break: keep-all; }
  section { padding: 58px 0; }
  .grid.two, .grid.three { grid-template-columns: 1fr; }
  .summary-section { padding: 58px 0; }
  .fact-grid { grid-template-columns: 1fr 1fr; gap: 8px; }
  .fact { min-height: 128px; padding: 18px; border-radius: 6px; }
  .fact strong { font-size: clamp(23px, 5.5vw, 28px); }
  .timeline { border-top: 0; }
  .timeline > li { display: block; padding: 0 0 28px; }
  .timeline > li + li { padding-top: 28px; }
  .timeline time { display: block; padding-top: 0; margin-bottom: 7px; }
  .case-study { grid-template-columns: 1fr; gap: 5px; }
  .study-controls { grid-template-columns: 1fr; }
  .study-layout { grid-template-columns: 1fr; gap: 28px; padding-top: 38px; }
  .study-aside { position: static; }
  .tech-content { grid-template-columns: 1fr; }
  .tech-full { grid-column: auto; }
}

@media (max-width: 1020px) and (min-width: 781px) {
  .fact-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 520px) {
  .fact-grid { grid-template-columns: 1fr; }
  .fact { min-height: 116px; }
}