:root {
  --night: #12303d;
  --text-on-night: #ffffff;
  --ink: #102833;
  --paper: #f4f8fa;
  --blue: #2f7df6;
  --orange: #f06a3a;
  --green: #277a59;
  --muted: #5e747d;
  --line: #cddce2;
  --white: #ffffff;
  --soft-blue: #dce9ff;
  --soft-orange: #ffe2d6;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-snap-type: y mandatory; }
body { margin: 0; color: var(--ink); background: var(--paper); font-family: Pretendard, "Apple SD Gothic Neo", "Noto Sans KR", sans-serif; }
a { color: inherit; }
.skip { position: fixed; z-index: 20; left: 1rem; top: -4rem; padding: .8rem 1rem; color: var(--white); background: var(--night); }
.skip:focus { top: 1rem; }
.deck-header { position: fixed; z-index: 10; inset: 0 0 auto 0; display: flex; justify-content: space-between; align-items: center; min-height: 54px; padding: 0 4vw; color: var(--night); background: color-mix(in srgb, var(--paper) 88%, transparent); border-bottom: 1px solid var(--line); backdrop-filter: blur(14px); }
.deck-header a { font-weight: 900; text-decoration: none; }
.deck-header span { color: var(--muted); font-size: .78rem; }
.scene-nav { position: fixed; z-index: 9; right: 1.4rem; top: 50%; display: grid; gap: .65rem; transform: translateY(-50%); }
.scene-nav a { width: 10px; height: 10px; border: 2px solid var(--night); border-radius: 50%; background: var(--paper); }
.scene-nav a:focus-visible { outline: 3px solid var(--orange); outline-offset: 4px; }
.scene { position: relative; min-height: 100svh; padding: clamp(5.5rem, 9vh, 8rem) clamp(2rem, 8vw, 9rem) clamp(3rem, 7vh, 6rem); overflow: hidden; scroll-snap-align: start; }
.scene h1, .scene h2, .scene h3, .scene p { margin-top: 0; }
.scene h1 { max-width: 10ch; margin-bottom: 1.4rem; font-size: clamp(3.9rem, 9vw, 8.6rem); line-height: .94; letter-spacing: -.075em; }
.scene h2 { max-width: 15ch; font-size: clamp(2.7rem, 6vw, 6.2rem); line-height: 1.02; letter-spacing: -.06em; }
.scene p { max-width: 58ch; font-size: clamp(1rem, 1.5vw, 1.4rem); line-height: 1.65; }
.scene-number { position: absolute; right: 5vw; top: 10vh; color: color-mix(in srgb, var(--night) 9%, transparent); font-size: min(34vw, 28rem); font-weight: 900; line-height: .7; pointer-events: none; }
.opening { display: grid; grid-template-columns: 1fr minmax(230px, .38fr); align-items: center; gap: 5vw; color: var(--white); background: var(--night); }
.opening .place { color: #a9d4e6; font-weight: 800; }
.opening-copy p:last-child { color: #d9ecf3; }
.opening-facts { display: grid; grid-template-columns: auto 1fr; align-items: baseline; gap: .2rem 1rem; padding: 2rem; color: var(--ink); background: var(--white); border-radius: 2rem 0 2rem 0; }
.opening-facts strong { color: var(--blue); font-size: clamp(2.5rem, 5vw, 5rem); }
.opening-facts span { font-weight: 800; }
.route-line { position: absolute; right: 0; bottom: 10%; display: flex; align-items: center; width: 42%; height: 4px; background: var(--blue); }
.route-line span { width: 18px; height: 18px; border: 4px solid var(--night); border-radius: 50%; background: var(--orange); }
.route-line span:nth-child(2) { margin-left: 28%; }
.route-line span:nth-child(3) { margin-left: auto; }
.problem { display: grid; grid-template-columns: minmax(0, 1fr) minmax(260px, .42fr); align-items: center; gap: 7vw; }
.problem .lead { font-size: clamp(1.2rem, 2vw, 1.8rem); }
.problem aside { position: relative; z-index: 1; padding: 2.2rem; color: var(--night); background: var(--soft-orange); border-left: 10px solid var(--orange); }
.problem aside span { display: inline-block; margin-top: 1rem; padding: .45rem .75rem; color: var(--white); background: var(--orange); font-weight: 900; }
.route-scene { color: var(--white); background: var(--blue); }
.journey { position: relative; z-index: 1; display: grid; grid-template-columns: repeat(4, 1fr); gap: 1px; max-width: 1100px; margin: 3rem 0 0; padding: 0; list-style: none; background: #8fb8ff; border: 1px solid #8fb8ff; }
.journey li { display: grid; min-height: 130px; padding: 1.2rem; background: #226de0; }
.journey li:nth-child(5), .journey li:nth-child(6), .journey li:nth-child(7) { background: #174f9f; }
.journey b { font-size: 1.25rem; }
.journey span { align-self: end; color: #dce9ff; line-height: 1.4; }
.demo-scene { background: #e8eff2; }
.demo-heading { display: flex; align-items: end; justify-content: space-between; gap: 2rem; }
.demo-heading p { max-width: 30ch; color: var(--muted); }
.phone-strip { position: relative; z-index: 1; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: clamp(.8rem, 2vw, 1.8rem); align-items: end; max-width: 1200px; margin-top: 1.5rem; }
.phone-strip figure { margin: 0; }
.phone-strip figure:nth-child(even) { transform: translateY(2rem); }
.phone-strip img { display: block; width: 100%; max-height: 54vh; object-fit: cover; object-position: top; border: 8px solid var(--night); border-radius: 1.8rem; background: var(--white); }
.phone-strip figcaption { margin-top: .7rem; font-weight: 900; }
.system-scene { color: var(--white); background: var(--night); }
.system-path { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr; align-items: center; gap: .9rem; max-width: 1200px; margin-top: 2.7rem; }
.system-path div { min-height: 150px; padding: 1.2rem; color: var(--ink); background: var(--white); }
.system-path b, .system-path span { display: block; }
.system-path b { font-size: 1.2rem; }
.system-path span { margin-top: 2.8rem; color: var(--muted); line-height: 1.4; }
.system-path i { width: 24px; height: 4px; background: var(--orange); }
.guardrails { columns: 2; max-width: 1050px; margin-top: 2rem; padding-left: 1.2rem; color: #c8e2ec; line-height: 1.8; }
.proof-scene { display: grid; grid-template-columns: .8fr 1.2fr; align-items: center; gap: 6vw; }
.proof-table { position: relative; z-index: 1; display: grid; gap: 1rem; }
.proof-table div { display: grid; grid-template-columns: 180px 1fr; align-items: center; min-height: 100px; padding: 1.2rem 1.5rem; border: 1px solid var(--line); background: var(--white); }
.proof-table div:first-child { border-left: 9px solid var(--green); }
.proof-table div:nth-child(2) { border-left: 9px solid var(--orange); }
.proof-table div:nth-child(3) { border-left: 9px solid var(--blue); }
.proof-table b { font-size: 1.6rem; }
.proof-scene > a { position: absolute; left: 8vw; bottom: 8vh; font-weight: 900; }
.next-scene { display: grid; grid-template-columns: 1fr .8fr; align-items: center; gap: 7vw; padding-bottom: 9rem; color: var(--white); background: var(--night); }
.next-scene ul { position: relative; z-index: 1; margin: 0; padding: 0; list-style: none; }
.next-scene li { padding: 1rem 0; border-bottom: 1px solid #42616d; line-height: 1.55; }
.next-scene li span { display: inline-block; width: 4rem; color: #9ed2e5; font-weight: 900; }
.last-line { position: absolute; inset: auto 0 0; display: flex; justify-content: space-between; gap: 1rem; padding: 1.5rem 8vw; color: var(--ink); background: var(--orange); }
.last-line strong { font-size: 1.25rem; }

@media (max-width: 760px) {
  html { scroll-snap-type: none; }
  .deck-header { padding: 0 1rem; }
  .deck-header span, .scene-nav { display: none; }
  .scene { min-height: auto; padding: 6rem 1.2rem 3.5rem; }
  .scene h1 { font-size: clamp(3.2rem, 17vw, 5.6rem); }
  .scene h2 { font-size: clamp(2.5rem, 13vw, 4.5rem); }
  .scene-number { right: -.4rem; top: 5.5rem; font-size: 13rem; }
  .opening, .problem, .proof-scene, .next-scene { grid-template-columns: 1fr; }
  .opening { gap: 2rem; }
  .opening-facts { max-width: 340px; }
  .route-line { display: none; }
  .journey { grid-template-columns: 1fr 1fr; }
  .demo-heading { display: block; }
  .phone-strip { grid-template-columns: 1fr 1fr; }
  .phone-strip figure:nth-child(even) { transform: none; }
  .phone-strip img { max-height: 420px; }
  .system-path { grid-template-columns: 1fr; }
  .system-path i { width: 4px; height: 22px; margin-left: 1rem; }
  .guardrails { columns: 1; }
  .proof-table div { grid-template-columns: 1fr; gap: .4rem; }
  .proof-scene > a { position: static; }
  .last-line { position: static; flex-direction: column; margin: 3rem -1.2rem -3.5rem; padding: 1.3rem 1.2rem; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}