/* 全体のスタイル */
body {
    font-family: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN", "Hiragino Sans", Meiryo, sans-serif;
    line-height: 1.6;
    color: #333;
    margin: 0;
    padding: 0;
    background-color: #f5f5f5;
}

/* ヘッダー */
.header {
    background-color: #1a237e;
    color: white;
    padding: 1rem 0;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.header h1 {
    margin: 0;
    font-size: 1.5rem;
}

.header nav {
    margin-top: 0.5rem;
}

.header nav a {
    color: white;
    text-decoration: none;
    margin-right: 1rem;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    transition: background-color 0.3s;
}

.header nav a:hover {
    background-color: rgba(255,255,255,0.1);
}

/* メインコンテンツ */
main {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
}

/* 記事一覧 */
.article-list {
    display: grid;
    gap: 1.5rem;
}

.article-item {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    transition: transform 0.2s, box-shadow 0.2s;
}

.article-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.article-item h2 {
    margin: 0 0 1rem 0;
    font-size: 1.25rem;
    color: #1a237e;
}

.article-item a {
    color: inherit;
    text-decoration: none;
}

.article-preview {
    color: #666;
    font-size: 0.9rem;
    margin-top: 0.5rem;
    line-height: 1.6;
}

/* 記事詳細 */
.article-content {
    background: white;
    border-radius: 8px;
    padding: 2rem;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.article-content h1 {
    margin: 0 0 1.5rem 0;
    font-size: 1.75rem;
    color: #1a237e;
    border-bottom: 2px solid #e0e0e0;
    padding-bottom: 1rem;
}

.article-text {
    font-size: 1rem;
    line-height: 1.8;
    color: #333;
}

.article-text p {
    margin: 1rem 0;
}

/* 検索フォーム */
.search-form {
    margin-bottom: 2rem;
    display: flex;
    gap: 1rem;
}

.search-form input[type="text"] {
    flex: 1;
    padding: 0.75rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 1rem;
}

.search-form button {
    padding: 0.75rem 1.5rem;
    background-color: #1a237e;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s;
}

.search-form button:hover {
    background-color: #283593;
}

/* 検索結果 */
.search-results {
    margin-bottom: 1rem;
    color: #666;
}

/* キーワードハイライト */
.highlight {
    background-color: #fff59d;
    padding: 0 2px;
    border-radius: 2px;
}

/* フッター */
.footer {
    background-color: #1a237e;
    color: white;
    padding: 2rem 0;
    margin-top: 3rem;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
    text-align: center;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
    .header h1 {
        font-size: 1.25rem;
    }
    
    .article-content {
        padding: 1rem;
    }
    
    .article-content h1 {
        font-size: 1.5rem;
    }
    
    .search-form {
        flex-direction: column;
    }
    
    .search-form button {
        width: 100%;
    }
}