:root {
  color-scheme: light dark;
  --background: #f7f8fc;
  --surface: #ffffff;
  --text: #172033;
  --muted: #5d687b;
  --line: #dfe4ee;
  --primary: #2563eb;
  --primary-soft: #e8efff;
  --accent: #f59e0b;
  --shadow: 0 14px 38px rgb(23 32 51 / 8%);
  font-family: Inter, Pretendard, "Apple SD Gothic Neo", system-ui, sans-serif;
  font-synthesis: none;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-width: 320px;
  background: var(--background);
  color: var(--text);
  line-height: 1.65;
  overflow-wrap: anywhere;
}

a { color: inherit; }

.skip-link {
  position: absolute;
  left: 12px;
  top: -80px;
  z-index: 10;
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--text);
  color: var(--surface);
}

.skip-link:focus { top: 12px; }

.hero {
  position: relative;
  overflow: hidden;
  padding: max(56px, env(safe-area-inset-top)) 20px 64px;
  color: #fff;
  background:
    radial-gradient(circle at 90% 15%, rgb(245 158 11 / 45%), transparent 24rem),
    linear-gradient(135deg, #172554 0%, #1d4ed8 65%, #2563eb 100%);
}

.hero::after {
  content: "";
  position: absolute;
  right: -42px;
  bottom: -95px;
  width: 240px;
  aspect-ratio: 1;
  border: 40px solid rgb(255 255 255 / 8%);
  border-radius: 50%;
}

.hero__inner,
.layout,
footer p {
  width: min(100%, 1080px);
  margin-inline: auto;
}

.eyebrow,
.section-kicker {
  margin: 0 0 8px;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.12em;
}

.eyebrow { color: #bfdbfe; }
.section-kicker { color: var(--primary); }

h1,
h2,
h3,
p { margin-top: 0; }

h1 {
  max-width: 780px;
  margin-bottom: 14px;
  font-size: clamp(2.25rem, 9vw, 4.8rem);
  line-height: 1.05;
  letter-spacing: -0.055em;
}

.hero__description {
  max-width: 650px;
  margin-bottom: 0;
  color: #dbeafe;
  font-size: clamp(1rem, 3vw, 1.2rem);
}

.layout {
  display: grid;
  gap: 56px;
  padding: 56px 20px 72px;
}

.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 20px;
}

h2 {
  margin-bottom: 0;
  font-size: clamp(1.55rem, 5vw, 2.15rem);
  line-height: 1.25;
  letter-spacing: -0.035em;
}

.count {
  flex: none;
  padding: 7px 11px;
  border-radius: 999px;
  background: var(--primary-soft);
  color: var(--primary);
  font-size: 0.875rem;
  font-weight: 700;
}

.lecture-card {
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: center;
  gap: 18px;
  padding: clamp(20px, 5vw, 34px);
  border: 1px solid var(--line);
  border-radius: 22px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.lecture-card__number {
  display: grid;
  place-items: center;
  width: 72px;
  aspect-ratio: 1;
  border-radius: 18px;
  background: var(--primary-soft);
  color: var(--primary);
  font-size: 1.5rem;
  font-weight: 800;
}

.lecture-card__status {
  margin-bottom: 6px;
  color: var(--primary);
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.lecture-card h3 { margin-bottom: 6px; font-size: clamp(1.2rem, 3vw, 1.55rem); }
.lecture-card h3 a { color: inherit; text-decoration: none; }
.lecture-card h3 a:hover,
.lecture-card h3 a:focus-visible { color: var(--primary); }
.lecture-card p { margin-bottom: 0; color: var(--muted); }

.lecture-card__links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 18px;
}

.lecture-card__links a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  color: var(--primary);
  font-size: 0.9rem;
  font-weight: 750;
  text-decoration: none;
}

.lecture-card__links a:hover,
.lecture-card__links a:focus-visible { background: var(--primary-soft); }

.guide {
  padding-top: 4px;
}

.steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
  margin: 24px 0 0;
  padding: 0;
  list-style: none;
}

.steps li {
  display: grid;
  align-content: start;
  gap: 14px;
  min-height: 190px;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--surface);
}

.steps li > span {
  display: grid;
  place-items: center;
  width: 34px;
  aspect-ratio: 1;
  border-radius: 50%;
  background: var(--text);
  color: var(--surface);
  font-size: 0.85rem;
  font-weight: 700;
}

.steps strong { display: block; margin-bottom: 4px; }
.steps p { margin-bottom: 0; color: var(--muted); font-size: 0.92rem; }

footer {
  padding: 24px 20px calc(24px + env(safe-area-inset-bottom));
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.875rem;
}

footer p { margin-bottom: 0; }

@media (max-width: 780px) {
  .steps { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
  .hero { padding-inline: 18px; padding-bottom: 48px; }
  .layout { padding: 42px 16px 56px; gap: 44px; }
  .section-heading { align-items: start; }
  .lecture-card { grid-template-columns: 1fr; }
  .lecture-card__number { width: 58px; border-radius: 14px; }
  .steps { grid-template-columns: 1fr; }
  .steps li { grid-template-columns: auto 1fr; min-height: 0; }
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #0f1420;
    --surface: #171e2d;
    --text: #edf2ff;
    --muted: #a8b2c6;
    --line: #2b3549;
    --primary: #8ab4ff;
    --primary-soft: #1d315c;
    --shadow: none;
  }
}

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