body {
  margin: 0;
  font-family: Arial, "Hiragino Kaku Gothic ProN", sans-serif;
  background: #0b1220;
  color: #e5e7eb;
}

/* ヘッダー */
.header {
  display: flex;
  justify-content: space-between;
  padding: 20px 40px;
  background: #111827;
  border-bottom: 1px solid #1f2937;
}

.logo {
  font-weight: bold;
  font-size: 18px;
}

nav a {
  color: #9ca3af;
  margin-left: 20px;
  text-decoration: none;
}

nav a:hover {
  color: white;
}

/* ヒーロー */
.hero {
  height: 60vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  background: linear-gradient(135deg, #1e293b, #0f172a);
}

.hero h1 {
  font-size: 42px;
  margin-bottom: 10px;
}

.hero p {
  color: #94a3b8;
}

.hero-inner {
  max-width: 600px;
}

/* ボタン */
.btn {
  display: inline-block;
  margin-top: 20px;
  padding: 12px 24px;
  background: #3b82f6;
  color: white;
  text-decoration: none;
  border-radius: 8px;
}

.btn:hover {
  background: #2563eb;
}

/* カード */
.cards {
  display: flex;
  justify-content: center;
  gap: 20px;
  padding: 60px 20px;
  flex-wrap: wrap;
}

.card {
  background: #111827;
  padding: 20px;
  border-radius: 10px;
  width: 220px;
  border: 1px solid #1f2937;
  text-align: center;
}

.card h2 {
  color: #60a5fa;
}

/* フッター */
.footer {
  text-align: center;
  padding: 20px;
  border-top: 1px solid #1f2937;
  color: #6b7280;
}