:root {
  --bg: #f4efe6;
  --bg-deep: #13212e;
  --panel: rgba(255, 248, 239, 0.9);
  --panel-strong: rgba(255, 251, 245, 0.96);
  --line: rgba(19, 33, 46, 0.12);
  --ink: #13212e;
  --muted: #5c6774;
  --accent: #df6d2d;
  --accent-cool: #2a8ca8;
  --accent-gold: #f2b84b;
  --shadow: 0 20px 60px rgba(19, 33, 46, 0.12);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "IBM Plex Sans KR", sans-serif;
  color: var(--ink);
  overflow-x: hidden;
  background:
    radial-gradient(circle at top left, rgba(242, 184, 75, 0.24), transparent 34%),
    radial-gradient(circle at top right, rgba(42, 140, 168, 0.2), transparent 28%),
    linear-gradient(180deg, #fff7ec 0%, #f4efe6 48%, #e7edf0 100%);
}

a {
  color: inherit;
  text-decoration: none;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  gap: 1rem;
  align-items: center;
  justify-content: space-between;
  padding: 1rem min(6vw, 5rem);
  background: rgba(255, 248, 239, 0.82);
  backdrop-filter: blur(18px);
  border-bottom: 1px solid rgba(19, 33, 46, 0.08);
}

.topbar__brand {
  font-family: "Space Grotesk", sans-serif;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.topbar__links {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 0.65rem 1rem;
  font-size: 0.9rem;
  color: var(--muted);
}

.topbar__links a,
.module-card__tagline,
.module-hero__tagline,
.hero__lede,
.module p,
.plain-list li {
  overflow-wrap: anywhere;
}

.hero {
  min-height: 88vh;
  padding: 5rem min(6vw, 5rem);
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) minmax(280px, 0.8fr);
  gap: 2rem;
  align-items: center;
}

.hero--compact {
  min-height: auto;
  padding-top: 3.5rem;
  padding-bottom: 2.5rem;
}

.hero__content h1,
.section-title h2,
.module h3 {
  font-family: "Space Grotesk", sans-serif;
  letter-spacing: -0.04em;
  overflow-wrap: anywhere;
}

.eyebrow {
  margin: 0 0 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--accent-cool);
  font-size: 0.78rem;
}

.hero__content h1 {
  margin: 0;
  max-width: 12ch;
  font-size: clamp(3rem, 7vw, 6rem);
  line-height: 0.95;
}

.hero__lede {
  max-width: 52rem;
  margin: 1.5rem 0 0;
  font-size: clamp(1rem, 1.8vw, 1.2rem);
  line-height: 1.7;
  color: var(--muted);
}

.hero__actions {
  margin-top: 2rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 999px;
  padding: 0.9rem 1.2rem;
  border: 1px solid transparent;
  font-weight: 600;
  cursor: pointer;
  transition: transform 180ms ease, background 180ms ease, color 180ms ease;
}

.button:hover {
  transform: translateY(-2px);
}

.button--solid {
  background: var(--ink);
  color: #fff6eb;
}

.button--ghost {
  border-color: rgba(19, 33, 46, 0.18);
  background: rgba(255, 255, 255, 0.42);
}

.button--small {
  background: linear-gradient(135deg, #f6c060, #df6d2d);
  color: #23170c;
  margin-top: 0.6rem;
  padding: 0.75rem 1rem;
}

.hero__panel {
  padding: 1.5rem;
  background: linear-gradient(180deg, rgba(19, 33, 46, 0.96), rgba(19, 33, 46, 0.82));
  color: #eef8ff;
  border-radius: 2rem;
  box-shadow: var(--shadow);
  position: relative;
  overflow: hidden;
}

.hero__panel::after {
  content: "";
  position: absolute;
  inset: auto -3rem -3rem auto;
  width: 16rem;
  height: 16rem;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(242, 184, 75, 0.3), transparent 68%);
}

.hero__grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
}

.hero__grid div {
  padding: 1.1rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 1.2rem;
  backdrop-filter: blur(16px);
}

.hero__grid span {
  display: block;
  font-size: 0.78rem;
  color: rgba(238, 248, 255, 0.7);
  margin-bottom: 0.4rem;
}

.hero__grid strong {
  font-size: 1.02rem;
}

main {
  padding: 0 min(6vw, 5rem) 5rem;
}

.overview,
.modules {
  margin-top: 2rem;
}

.modules--cards {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.section-title {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  margin-bottom: 1.5rem;
}

.section-title h2 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3.2rem);
}

.overview__cards {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.overview__cards article,
.module {
  background: var(--panel);
  border: 1px solid rgba(19, 33, 46, 0.08);
  border-radius: 1.8rem;
  box-shadow: var(--shadow);
}

.overview__cards article {
  padding: 1.4rem;
}

.overview__cards h3,
.module h3 {
  margin: 0 0 0.6rem;
}

.overview__cards p,
.module p {
  margin: 0;
  line-height: 1.7;
  color: var(--muted);
}

.modules {
  display: grid;
  gap: 1.4rem;
}

.module-card {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  padding: 1.4rem;
  background: var(--panel);
  border: 1px solid rgba(19, 33, 46, 0.08);
  border-radius: 1.8rem;
  box-shadow: var(--shadow);
}

.module-card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.module-card__tag {
  margin: 0;
  color: var(--accent-cool);
  font-size: 0.84rem;
  font-weight: 700;
  letter-spacing: 0.12em;
}

.module-card__tagline,
.module-hero__tagline {
  margin: 0;
  font-size: 1.05rem;
  color: var(--accent);
  font-weight: 600;
}

.module {
  padding: 1.3rem;
  display: grid;
  grid-template-columns: minmax(280px, 0.95fr) minmax(320px, 1.05fr);
  gap: 1rem;
  align-items: stretch;
}

.module--wide {
  grid-template-columns: minmax(280px, 0.8fr) minmax(360px, 1.2fr);
}

.module--detail {
  align-items: start;
}

.module__copy {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  min-width: 0;
}

.module__number {
  display: inline-flex;
  width: fit-content;
  align-items: center;
  justify-content: center;
  padding: 0.25rem 0.7rem;
  border-radius: 999px;
  background: rgba(42, 140, 168, 0.12);
  color: var(--accent-cool);
  font-weight: 700;
  font-size: 0.82rem;
}

.control {
  display: grid;
  gap: 0.4rem;
}

.control label {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: baseline;
  font-size: 0.96rem;
  font-weight: 500;
}

.control input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

.stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.75rem;
}

.stats div {
  padding: 0.95rem;
  background: var(--panel-strong);
  border: 1px solid var(--line);
  border-radius: 1.1rem;
}

.stats span {
  display: block;
  font-size: 0.8rem;
  color: var(--muted);
  margin-bottom: 0.35rem;
}

.stats strong {
  font-size: 1rem;
}

.module__hint {
  padding: 0.95rem 1rem;
  border-left: 4px solid var(--accent-gold);
  background: rgba(242, 184, 75, 0.12);
  border-radius: 0 1rem 1rem 0;
}

.module__visual {
  min-height: 360px;
  min-width: 0;
}

.scene-host,
.diagram-canvas {
  width: 100%;
  height: 100%;
  min-height: 360px;
  border-radius: 1.5rem;
  overflow: hidden;
  background:
    radial-gradient(circle at top, rgba(255, 255, 255, 0.55), transparent 42%),
    linear-gradient(180deg, rgba(19, 33, 46, 0.92), rgba(12, 18, 24, 0.98));
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.diagram-canvas {
  display: block;
  min-height: 420px;
  background: linear-gradient(180deg, rgba(255, 249, 242, 0.96), rgba(236, 243, 247, 0.96));
}

.module-hero {
  padding: 3rem min(6vw, 5rem) 1rem;
}

.module-hero__copy {
  max-width: 62rem;
}

.module-hero__copy h1 {
  margin: 0;
  font-family: "Space Grotesk", sans-serif;
  letter-spacing: -0.04em;
  font-size: clamp(2.4rem, 5vw, 4.4rem);
  line-height: 0.95;
}

.module-detail,
.formula-section {
  margin-top: 2rem;
}

.formula-grid,
.explain-grid {
  display: grid;
  gap: 1rem;
}

.formula-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.explain-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: 1rem;
}

.formula-card,
.info-card {
  padding: 1.4rem;
  background: var(--panel);
  border: 1px solid rgba(19, 33, 46, 0.08);
  border-radius: 1.5rem;
  box-shadow: var(--shadow);
}

.formula-card__label {
  margin: 0 0 0.75rem;
  color: var(--accent-cool);
  font-size: 0.84rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.equation {
  margin-bottom: 0.8rem;
  padding: 0.9rem 1rem;
  border-radius: 1rem;
  background: rgba(19, 33, 46, 0.95);
  color: #fff7e8;
  font-family: "Space Grotesk", sans-serif;
  font-size: clamp(1.15rem, 2vw, 1.5rem);
  line-height: 1.4;
  overflow-x: auto;
}

.info-card h3 {
  margin: 0 0 0.85rem;
}

.plain-list {
  margin: 0;
  padding-left: 1.15rem;
  color: var(--muted);
  line-height: 1.8;
}

.footer {
  padding: 2rem min(6vw, 5rem) 3rem;
  color: var(--muted);
}

@media (max-width: 1080px) {
  .hero,
  .module,
  .module--wide {
    grid-template-columns: 1fr;
  }

  .overview__cards {
    grid-template-columns: 1fr;
  }

  .modules--cards,
  .formula-grid,
  .explain-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 720px) {
  .topbar {
    position: static;
    padding-left: 1rem;
    padding-right: 1rem;
    align-items: flex-start;
    flex-direction: column;
  }

  .topbar__links {
    width: 100%;
    flex-wrap: nowrap;
    justify-content: flex-start;
    overflow-x: auto;
    padding-bottom: 0.25rem;
    scrollbar-width: thin;
  }

  .topbar__links a {
    white-space: nowrap;
  }

  .hero {
    padding-top: 3.5rem;
    min-height: auto;
    gap: 1.25rem;
  }

  .hero__content h1 {
    max-width: none;
    font-size: clamp(2.3rem, 12vw, 3.5rem);
  }

  .hero__panel,
  .overview__cards article,
  .module,
  .module-card,
  .formula-card,
  .info-card {
    border-radius: 1.3rem;
  }

  main,
  .footer {
    padding-left: 1rem;
    padding-right: 1rem;
  }

  .module {
    padding: 1rem;
  }

  .control label {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.35rem;
  }

  .stats {
    grid-template-columns: 1fr;
  }

  .hero__grid {
    grid-template-columns: 1fr;
  }

  .module__visual,
  .scene-host {
    min-height: 280px;
  }

  .diagram-canvas {
    min-height: 540px;
  }

  .equation {
    padding: 0.8rem 0.9rem;
    font-size: 1rem;
  }
}