/* ベース設定 */
body {
  font-family: "Noto Sans JP", sans-serif;
  background: #f9f9f9;
  color: #333;
  margin: 0;
  padding: 0;
}

/* コンテナ */
.container {
  width: 90%;
  max-width: 1100px;
  margin: 0 auto;
}

/* ヘッダー */
header {
  background: #232f3e;
  color: white;
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 10;
}

header h1 {
  margin: 0;
  font-size: 1.8rem;
}

nav ul {
  list-style: none;
  padding: 0;
  margin: 0.5rem 0 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

nav a {
  color: #ff9900;
  text-decoration: none;
  font-weight: bold;
}

nav a:hover {
  text-decoration: underline;
}

/* ヒーローセクション */
.hero {
  background: linear-gradient(135deg, #232f3e, #31465b);
  color: white;
  text-align: center;
  padding: 4rem 1rem;
}

.hero h2 {
  font-size: 2rem;
  margin-bottom: 1rem;
}

.hero p {
  font-size: 1.1rem;
  margin-bottom: 2rem;
}

.btn {
  background: #ff9900;
  color: white;
  padding: 0.8rem 1.4rem;
  border-radius: 6px;
  text-decoration: none;
  font-weight: bold;
}

.btn:hover {
  background: #cc7a00;
}

/* セクション */
.section {
  padding: 2rem 1rem;
}

.section h2 {
  text-align: center;
  font-size: 1.6rem;
  margin-bottom: 1.5rem;
  color: #232f3e;
}

/* 動画カード */
.videos-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 1.5rem;
}

.video-card {
  background: #fff;
  border-radius: 12px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
  padding: 1rem;
  transition: transform 0.2s ease;
}

.video-card:hover {
  transform: translateY(-5px);
}

.video-card iframe {
  width: 100%;
  aspect-ratio: 16 / 9;
  border-radius: 8px;
}

.video-card h3 {
  margin: 0.8rem 0 0.4rem;
  color: #232f3e;
}

.video-card p {
  font-size: 0.95rem;
  line-height: 1.5;
}

/* タグ */
.tags {
  margin-top: 0.6rem;
}

.tag {
  display: inline-block;
  background: #ff9900;
  color: white;
  border-radius: 8px;
  padding: 3px 8px;
  font-size: 0.8rem;
  margin-right: 4px;
}

/* フッター */
footer {
  background: #232f3e;
  color: white;
  text-align: center;
  padding: 1rem;
  font-size: 0.9rem;
}

footer a {
  color: #ff9900;
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

/* ▼スマホ対応▼ */
@media (max-width: 768px) {
  header h1 {
    font-size: 1.4rem;
  }
  .hero h2 {
    font-size: 1.6rem;
  }
  .videos-grid {
    grid-template-columns: 1fr;
  }
}