/* リセット & ベーススタイル */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Hiragino Sans', 'Hiragino Kaku Gothic ProN', Meiryo, sans-serif;
    line-height: 1.6;
    color: #333;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    overflow: hidden;
    min-height: calc(100vh - 40px);
    display: flex;
    flex-direction: column;
}

/* ヘッダー */
header {
    position: relative;
    background-image: url('images/biochem_old.jpg');
    background-size: cover;
    background-position: center;
    color: white;
    text-align: center;
    padding: 60px 20px;
    overflow: hidden;
}

.header-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.4) 0%, rgba(118, 75, 162, 0.4) 100%);
    z-index: 1;
}

.header-content {
    position: relative;
    z-index: 2;
}

.logo {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 10px;
    letter-spacing: -1px;
}

.tagline {
    font-size: 1.2rem;
    opacity: 0.9;
}

/* メインコンテンツ */
main {
    flex: 1;
    padding: 60px 40px;
}

.links-section h2 {
    font-size: 1.8rem;
    margin-bottom: 30px;
    color: #667eea;
}

.links-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 24px;
}

.link-card {
    display: block;
    padding: 30px;
    background: #f8f9fa;
    border-radius: 12px;
    text-decoration: none;
    color: #333;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.link-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(102, 126, 234, 0.3);
    border-color: #667eea;
}

.link-icon {
    font-size: 3rem;
    margin-bottom: 15px;
}

.link-card h3 {
    font-size: 1.3rem;
    margin-bottom: 10px;
    color: #667eea;
}

.link-card p {
    font-size: 0.95rem;
    color: #666;
    line-height: 1.5;
}

/* フッター */
footer {
    background: #f8f9fa;
    text-align: center;
    padding: 30px 20px;
    color: #666;
    font-size: 0.9rem;
}

/* レスポンシブ対応 */
@media (max-width: 768px) {
    body {
        padding: 10px;
    }

    .container {
        border-radius: 15px;
        min-height: calc(100vh - 20px);
    }

    header {
        padding: 40px 20px;
        background-position: center center;
    }

    .logo {
        font-size: 2rem;
    }

    .tagline {
        font-size: 1rem;
    }

    main {
        padding: 40px 20px;
    }

    .links-section h2 {
        font-size: 1.5rem;
    }

    .links-grid {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .link-card {
        padding: 24px;
    }
}

@media (max-width: 480px) {
    .logo {
        font-size: 1.8rem;
    }

    header {
        padding: 30px 15px;
    }

    main {
        padding: 30px 15px;
    }
}