/* 全体の基本設定 */
body {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  margin: 0;
  padding: 0;
  background-color: #fafafa;
  color: #333;
}

/* ヘッダー */
header {
  background-color: #2c3e50;
  color: white;
  padding: 20px;
}

header h1 {
  margin: 0;
  font-size: 24px;
}

header nav a {
  color: white;
  margin-right: 20px;
  text-decoration: none;
  font-weight: bold;
}

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

/* コンテンツ領域 */
h2 {
  font-size: 28px;
  color: #2c3e50;
}

h3 {
  font-size: 20px;
  margin-bottom: 10px;
}

img {
  max-width: 100%;
  border-radius: 4px;
}

a {
  color: #2c3e50;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* カードスタイル */
div.card {
  border: 1px solid #ccc;
  padding: 20px;
  border-radius: 8px;
  background-color: white;
  box-shadow: 0 2px 4px rgba(0,0,0,0.05);
  margin-bottom: 20px;
}

/* フッター */
footer {
  background-color: #f5f5f5;
  padding: 20px;
  text-align: center;
  font-size: 14px;
  color: #666;
  margin-top: 40px;
}

/* レスポンシブ対応 */
@media screen and (max-width: 768px) {
  header nav {
    display: flex;
    flex-direction: column;
    gap: 10px;
  }

  .card-container {
    flex-direction: column;
  }
}