:root {
  color-scheme: light;
  --ink: #15202b;
  --muted: #5b6b79;
  --line: #d9e2ec;
  --bg: #f7fafc;
  --card: #ffffff;
  --accent: #2563eb;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family:
    Pretendard,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(37, 99, 235, 0.08), transparent 40%),
    var(--bg);
  line-height: 1.7;
}

main {
  max-width: 760px;
  margin: 0 auto;
  padding: 48px 20px 80px;
}

a {
  color: var(--accent);
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 14px;
  margin-bottom: 28px;
  font-size: 14px;
}

.site-nav a {
  text-decoration: none;
  font-weight: 600;
  color: var(--muted);
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--accent);
}

h1 {
  margin: 0 0 8px;
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  line-height: 1.25;
}

.meta {
  color: var(--muted);
  margin-bottom: 32px;
}

.lead {
  font-size: 1.05rem;
  color: #334e68;
  margin: 0 0 24px;
}

section {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 24px;
  margin-bottom: 16px;
}

h2 {
  margin: 0 0 12px;
  font-size: 1.1rem;
}

p,
li {
  color: #334e68;
}

ul,
ol {
  margin: 0;
  padding-left: 1.2rem;
}

li + li {
  margin-top: 6px;
}

.site-footer-links {
  margin-top: 32px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  gap: 10px 16px;
  font-size: 13px;
}

.site-footer-links a {
  color: var(--muted);
  text-decoration: none;
}

.site-footer-links a:hover {
  color: var(--accent);
  text-decoration: underline;
}

.article-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.article-list li {
  margin: 0;
  padding: 14px 0;
  border-top: 1px solid var(--line);
}

.article-list li:last-child {
  border-bottom: 1px solid var(--line);
}

.article-list a {
  font-weight: 700;
  text-decoration: none;
  color: var(--ink);
}

.article-list a:hover {
  color: var(--accent);
}

.article-list p {
  margin: 6px 0 0;
  font-size: 0.95rem;
}

.article-nav {
  margin: 28px 0 0;
  padding-top: 16px;
  border-top: 1px solid var(--line);
  font-size: 14px;
}

.callout {
  margin: 16px 0 0;
  padding: 14px 16px;
  border-radius: 12px;
  border: 1px solid #c7d7fe;
  background: #eff4ff;
  color: #334e68;
  font-size: 0.95rem;
}

.example-box {
  margin: 14px 0 0;
  padding: 16px;
  border-radius: 12px;
  border: 1px dashed var(--line);
  background: #f8fafc;
}

.example-box h3 {
  margin: 0 0 8px;
  font-size: 1rem;
}

.diagram {
  display: block;
  width: 100%;
  max-width: 420px;
  margin: 12px 0;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: #fff;
}

.landing-button.secondary {
  background: transparent;
  color: var(--accent);
  border: 1px solid rgba(37, 99, 235, 0.35);
}

kbd {
  display: inline-block;
  min-width: 1.4em;
  padding: 0 5px;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: #eef2f7;
  font-size: 0.85em;
  font-family: inherit;
  text-align: center;
}

.landing-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 22px;
  border-radius: 12px;
  background: var(--accent);
  color: #fff;
  font-weight: 700;
  text-decoration: none;
  transition:
    transform 0.2s ease,
    background 0.2s ease,
    box-shadow 0.2s ease;
}

.landing-button:hover {
  transform: translateY(-1px);
  background: #1d4ed8;
  box-shadow: 0 14px 28px rgba(37, 99, 235, 0.22);
}

.landing-button.ghost {
  background: rgba(255, 255, 255, 0.72);
  color: var(--ink);
  border: 1px solid rgba(21, 32, 43, 0.12);
  backdrop-filter: blur(8px);
}

.landing-button.ghost:hover {
  background: #fff;
  box-shadow: none;
}

/* Landing: full-viewport background + centered content */
html:has(body.page-landing) {
  min-height: 100%;
  background: #f7fafc;
}

body.page-landing {
  --ink: #142033;
  --muted: #5a6b7d;
  --accent: #1f6feb;
  position: relative;
  min-height: 100dvh;
  background: transparent;
  overflow-x: hidden;
}

body.page-landing::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background:
    radial-gradient(ellipse 80% 55% at 18% 12%, #ffffff 0%, transparent 55%),
    radial-gradient(ellipse 70% 50% at 88% 18%, rgba(56, 189, 248, 0.16), transparent 50%),
    radial-gradient(ellipse 60% 45% at 70% 88%, rgba(37, 99, 235, 0.1), transparent 55%),
    linear-gradient(180deg, #ffffff 0%, #f7fafc 55%, #eef4fb 100%);
}

body.page-landing main {
  max-width: none;
  margin: 0;
  padding: 0;
}

.hero-screen {
  position: relative;
  min-height: 100dvh;
  display: grid;
  grid-template-rows: auto 1fr auto;
  width: 100%;
  margin: 0;
  padding: clamp(20px, 3.5vh, 36px) 0 24px;
  color: var(--ink);
}

.hero-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  width: 100%;
  padding: 0 clamp(48px, 12vw, 160px) 0 clamp(28px, 7vw, 96px);
  animation: rise-in 0.7s ease both;
}

.hero-nav-brand {
  font-family: "IBM Plex Sans", Pretendard, sans-serif;
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: -0.02em;
  color: var(--ink);
  text-decoration: none;
}

.hero-nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
  font-size: 0.92rem;
}

.hero-nav-links a {
  color: var(--muted);
  text-decoration: none;
  font-weight: 600;
}

.hero-nav-links a:hover {
  color: var(--accent);
}

.hero-stage {
  display: grid;
  grid-template-columns: minmax(260px, 0.82fr) minmax(0, 1.38fr);
  gap: clamp(20px, 2.5vw, 36px);
  align-items: center;
  min-height: 0;
  width: 100%;
  margin: 0;
  padding: clamp(12px, 3vh, 36px) clamp(20px, 4vw, 56px) clamp(12px, 3vh, 36px)
    clamp(28px, 7vw, 96px);
}

.hero-board {
  position: relative;
  min-height: clamp(280px, 52vh, 540px);
  margin-left: clamp(-112px, calc(-6vw - 48px), -80px);
  margin-right: 0;
  animation: rise-in 1s 0.16s ease both;
}

.hero-board-sheet {
  position: absolute;
  inset: 0;
  border-radius: 28px 28px 28px 28px;
  background: linear-gradient(180deg, #ffffff, #f8fbff);
  border: 1px solid rgba(33, 93, 161, 0.9);
  box-shadow:
    0 30px 80px rgba(36, 58, 94, 0.12),
    0 2px 0 rgba(255, 255, 255, 0.95) inset;
  overflow: hidden;
}

.hero-copy {
  max-width: 34rem;
  justify-self: start;
  align-self: center;
  padding-right: clamp(8px, 2vw, 24px);
  animation: rise-in 0.85s 0.08s ease both;
}

.hero-title {
  margin: 0 0 16px;
  font-family: "IBM Plex Sans", Pretendard, sans-serif;
  font-size: clamp(2.8rem, 7vw, 5.4rem);
  font-weight: 800;
  line-height: 1.05;
  letter-spacing: -0.04em;
  color: var(--ink);
}

.hero-lead {
  margin: 0;
  max-width: 28rem;
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  line-height: 1.65;
  color: #3d5168;
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.hero-board-sheet::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(100, 130, 170, 0.08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(100, 130, 170, 0.08) 1px, transparent 1px);
  background-size: 32px 32px;
}

.hero-sketch {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 74%;
  height: 74%;
  transform: translate(-50%, -50%);
  color: #1f6feb;
}

.sketch-line,
.sketch-shape {
  stroke-dasharray: 900;
  stroke-dashoffset: 900;
  animation: draw-stroke 2.4s ease forwards;
}

.sketch-a {
  animation-delay: 0.35s;
  color: #1f6feb;
}
.sketch-b {
  animation-delay: 0.7s;
  color: #0f766e;
}
.sketch-c {
  animation-delay: 1s;
  color: #c2410c;
}
.sketch-d {
  animation-delay: 1.25s;
  color: #1f6feb;
}
.sketch-e {
  animation-delay: 1.45s;
  color: #334155;
}

.hero-board-glow {
  position: absolute;
  right: -10%;
  bottom: -20%;
  width: 55%;
  height: 55%;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(56, 189, 248, 0.28), transparent 70%);
  pointer-events: none;
  animation: glow-pulse 5s ease-in-out infinite;
}

.hero-scroll {
  justify-self: center;
  margin-bottom: 8px;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--muted);
  text-decoration: none;
  letter-spacing: 0.02em;
  animation: rise-in 1s 0.4s ease both;
}

.hero-scroll:hover {
  color: var(--accent);
}

.landing-details {
  max-width: 760px;
  margin: 0 auto;
  padding: 56px 20px 80px;
}

.landing-details section {
  background: rgba(255, 255, 255, 0.88);
  border: 1px solid rgba(217, 226, 236, 0.9);
  border-radius: 16px;
  padding: 24px;
  margin-bottom: 16px;
  backdrop-filter: blur(8px);
}

@keyframes rise-in {
  from {
    opacity: 0;
    transform: translateY(18px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes draw-stroke {
  to {
    stroke-dashoffset: 0;
  }
}

@keyframes glow-pulse {
  0%,
  100% {
    opacity: 0.7;
    transform: scale(1);
  }
  50% {
    opacity: 1;
    transform: scale(1.06);
  }
}

@media (max-width: 900px) {
  .hero-nav {
    padding: 0 24px;
  }

  .hero-stage {
    width: 100%;
    padding: clamp(12px, 3vh, 36px) 24px;
    grid-template-columns: 1fr;
    align-content: center;
  }

  .hero-copy {
    justify-self: stretch;
    padding-right: 0;
    max-width: none;
  }

  .hero-board {
    min-height: clamp(220px, 38vh, 340px);
    margin-left: 0;
    margin-right: 0;
    order: -1;
  }

  .hero-board-sheet {
    border-radius: 22px;
  }

  .hero-title {
    font-size: clamp(2.4rem, 11vw, 3.6rem);
  }
}

@media (max-width: 560px) {
  .hero-nav-brand {
    width: 100%;
  }

  .hero-cta {
    width: 100%;
  }

  .hero-cta .landing-button {
    flex: 1 1 auto;
  }
}

@media (prefers-reduced-motion: reduce) {
  .hero-board-glow,
  .hero-nav,
  .hero-copy,
  .hero-board,
  .hero-scroll,
  .sketch-line,
  .sketch-shape {
    animation: none !important;
  }

  .sketch-line,
  .sketch-shape {
    stroke-dasharray: none;
    stroke-dashoffset: 0;
  }
}