:root {
  --bg: #111827;
  --text: #f9fafb;
  --sub: #9ca3af;
  --card: #1f2937;
  --accent: #60a5fa;
}

body.light {
  --bg: #f9fafb;
  --text: #111827;
  --sub: #4b5563;
  --card: #ffffff;
  --accent: #2563eb;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Arial, "Hiragino Sans", "Yu Gothic", sans-serif;
  background: var(--bg);
  color: var(--text);
  transition: background 0.3s, color 0.3s;
}

.hero {
  min-height: 60vh;
  display: grid;
  place-content: center;
  text-align: center;
  padding: 48px 24px;
}

.tag {
  color: var(--accent);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  font-size: 14px;
}

h1 {
  font-size: clamp(48px, 10vw, 96px);
  margin: 8px 0;
}

.lead {
  color: var(--sub);
  font-size: 18px;
  line-height: 1.8;
}

button {
  margin-top: 24px;
  padding: 12px 20px;
  border: none;
  border-radius: 999px;
  background: var(--accent);
  color: white;
  font-weight: bold;
  cursor: pointer;
}

button:hover {
  opacity: 0.85;
}

main {
  width: min(900px, 92%);
  margin: 0 auto 64px;
  display: grid;
  gap: 24px;
}

.card {
  background: var(--card);
  border-radius: 24px;
  padding: 28px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.25);
}

.card h2 {
  margin-top: 0;
}

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

footer {
  text-align: center;
  color: var(--sub);
  padding: 32px;
}