/* 基本的なリセットとフォント設定 */
body {
    font-family: 'Segoe UI', 'メイリオ', Meiryo, 'ヒラギノ角ゴ Pro W3', 'Hiragino Kaku Gothic Pro', Osaka, 'ＭＳ Ｐゴシック', 'MS PGothic', sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background-color: #f4f7f6;
    color: #333;
}

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ヘッダー */
header {
    background-color: #2c3e50; /* ダークブルー */
    color: #fff;
    padding: 1rem 0;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

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

header h1 a {
    color: #fff;
    text-decoration: none;
}

header nav ul {
    list-style: none;
    padding: 0;
    margin: 10px 0 0;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
}

header nav ul li {
    margin: 0 15px;
}

header nav ul li a {
    color: #fff;
    text-decoration: none;
    font-weight: bold;
    padding: 5px 0;
    transition: color 0.3s ease;
}

header nav ul li a:hover {
    color: #ecf0f1; /* ライトグレー */
}

/* ヒーローセクション */
.hero {
    background-color: #34495e; /* ミディアムブルー */
    color: #fff;
    text-align: center;
    padding: 4rem 0;
    margin-bottom: 20px;
}

.hero h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

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

.button {
    display: inline-block;
    background-color: #e67e22; /* オレンジ */
    color: #fff;
    padding: 12px 25px;
    text-decoration: none;
    border-radius: 5px;
    font-weight: bold;
    transition: background-color 0.3s ease;
}

.button:hover {
    background-color: #d35400; /* ダークオレンジ */
}

/* コンテンツセクション */
.content-section {
    background-color: #fff;
    padding: 30px 0;
    margin-bottom: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

.content-section h2, .content-section h3 {
    color: #2c3e50;
    text-align: center;
    margin-bottom: 25px;
    font-size: 2rem;
}

.content-section h3 {
    font-size: 1.6rem;
}

.content-section p, .content-section ul {
    margin-bottom: 15px;
    font-size: 1rem;
    line-height: 1.8;
    color: #555;
}

.content-section ul {
    list-style: disc;
    margin-left: 25px;
}

.content-section ul li {
    margin-bottom: 8px;
}

.content-section a {
    color: #3498db; /* スカイブルー */
    text-decoration: none;
}

.content-section a:hover {
    text-decoration: underline;
}

.article-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
    margin-top: 30px;
}

.card {
    background-color: #f9f9f9;
    border: 1px solid #ddd;
    border-radius: 8px;
    padding: 20px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
    transition: transform 0.2s ease;
}

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

.card h4 {
    margin-top: 0;
    font-size: 1.2rem;
    margin-bottom: 10px;
}

.card h4 a {
    color: #2c3e50;
    text-decoration: none;
}

.card h4 a:hover {
    text-decoration: underline;
}

.card p {
    font-size: 0.95rem;
    color: #666;
    margin-bottom: 15px;
}

.read-more {
    display: inline-block;
    color: #e67e22;
    font-weight: bold;
    text-decoration: none;
}

.read-more:hover {
    text-decoration: underline;
}

.placeholder-text {
    font-style: italic;
    color: #888;
    text-align: center;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px dashed #eee;
}

/* フッター */
footer {
    background-color: #2c3e50;
    color: #fff;
    text-align: center;
    padding: 1.5rem 0;
    font-size: 0.9rem;
}

footer ul {
    list-style: none;
    padding: 0;
    margin: 10px 0 0;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
}

footer ul li {
    margin: 0 10px;
}

footer ul li a {
    color: #fff;
    text-decoration: none;
    transition: color 0.3s ease;
}

footer ul li a:hover {
    color: #ecf0f1;
}

/* レスポンシブ対応 */
@media (max-width: 768px) {
    header h1 {
        font-size: 1.5rem;
    }

    header nav ul {
        flex-direction: column;
        align-items: center;
    }

    header nav ul li {
        margin: 5px 0;
    }

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

    .hero p {
        font-size: 1rem;
    }

    .article-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }

    header h1 {
        font-size: 1.3rem;
    }

    .hero h2 {
        font-size: 1.8rem;
    }

    .button {
        padding: 10px 20px;
        font-size: 0.9rem;
    }

    .content-section h2 {
        font-size: 1.8rem;
    }

    .content-section h3 {
        font-size: 1.4rem;
    }
}