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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic", YuGothic, Meiryo, sans-serif;
    line-height: 1.8;
    color: #2c3e50;
    background-color: #ecf0f1;
    font-size: 16px;
}

.container {
    max-width: 850px;
    margin: 0 auto;
    background-color: #fff;
}

/* ヘッダー - 改善版 */
header {
    background: linear-gradient(135deg, #34495e 0%, #2c3e50 100%);
    color: #ecf0f1;
    padding: 80px 40px 70px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

/* ヘッダー背景の装飾 */
header::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 500px;
    height: 500px;
    background: rgba(52, 152, 219, 0.1);
    border-radius: 50%;
}

header::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -5%;
    width: 400px;
    height: 400px;
    background: rgba(52, 152, 219, 0.08);
    border-radius: 50%;
}

/* ヘッダーコンテンツを前面に */
header > * {
    position: relative;
    z-index: 1;
}

/* タイトル上部の装飾ライン */
header h1::before {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, #3498db 0%, #5dade2 100%);
    margin: 0 auto 25px;
}

header h1 {
    font-size: 2.0em;
    margin-bottom: 20px;
    font-weight: 400;
    letter-spacing: 0.05em;
    line-height: 1.3;
}

/* サブタイトルの装飾 */
.subtitle {
    font-size: 1.0em;
    opacity: 0.95;
    font-weight: 300;
    max-width: 680px;
    margin: 0 auto;
    padding: 20px 30px;
    border-top: 1px solid rgba(236, 240, 241, 0.2);
    border-bottom: 1px solid rgba(236, 240, 241, 0.2);
    line-height: 1.8;
}

/* 目次 */
.table-of-contents {
    background-color: #f8f9fa;
    padding: 50px 35px;
    border-bottom: 2px solid #bdc3c7;
}

.toc-title {
    font-size: 1.7em;
    color: #34495e;
    margin-bottom: 35px;
    text-align: center;
    font-weight: 400;
    position: relative;
    padding-bottom: 15px;
}

/* 目次タイトルの装飾 */
.toc-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 2px;
    background: linear-gradient(90deg, transparent 0%, #3498db 50%, transparent 100%);
}

.toc-list {
    max-width: 680px;
    margin: 0 auto;
    padding-left: 0;
    list-style: none;
}

.toc-list li {
    margin-bottom: 10px;
    position: relative;
}

/* 目次の番号装飾 */
.toc-list li::before {
    content: '';
    position: absolute;
    left: 8px;
    top: 50%;
    transform: translateY(-50%);
    width: 6px;
    height: 6px;
    background-color: #3498db;
    border-radius: 50%;
    transition: all 0.3s ease;
}

.toc-list li:hover::before {
    width: 8px;
    height: 8px;
    background-color: #2980b9;
}

.toc-list a {
    color: #2c3e50;
    text-decoration: none;
    font-size: 0.98em;
    display: block;
    padding: 13px 20px 13px 30px;
    border-left: 3px solid transparent;
    transition: all 0.3s ease;
    border-radius: 4px;
}

.toc-list a:hover {
    background-color: #ecf0f1;
    border-left-color: #3498db;
    color: #3498db;
    padding-left: 35px;
}

/* メインコンテンツ */
main {
    padding: 55px 35px;
}

/* カテゴリセクション */
.category {
    margin-bottom: 75px;
    padding-bottom: 55px;
    border-bottom: 1px solid #e0e0e0;
}

.category:last-of-type {
    border-bottom: none;
}

.category-title {
    font-size: 1.65em;
    color: #34495e;
    margin-bottom: 30px;
    font-weight: 400;
    padding-bottom: 15px;
    border-bottom: 2px solid #95a5a6;
    position: relative;
}

/* カテゴリタイトルの装飾 */
.category-title::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 60px;
    height: 2px;
    background-color: #3498db;
}

/* マインドセット */
.mindset {
    background: linear-gradient(135deg, #f8f9fa 0%, #ecf0f1 100%);
    border-left: 4px solid #3498db;
    padding: 25px 28px;
    margin-bottom: 38px;
    border-radius: 4px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.mindset-title {
    font-weight: 500;
    font-size: 1.05em;
    color: #2c3e50;
    margin-bottom: 12px;
}

.mindset-details {
    margin-top: 12px;
}

.mindset-details summary {
    cursor: pointer;
    color: #7f8c8d;
    font-weight: 400;
    padding: 10px 0;
    font-size: 0.92em;
    transition: color 0.2s ease;
}

.mindset-details summary:hover {
    color: #3498db;
}

.mindset-details p {
    margin-top: 15px;
    padding: 18px;
    background-color: #fff;
    color: #555;
    font-size: 0.92em;
    border-radius: 3px;
    box-shadow: 0 1px 4px rgba(0, 0, 0, 0.08);
}

/* チェックリストセクション */
.checklist-section {
    margin-bottom: 45px;
}

.checklist-section h3 {
    font-size: 1.25em;
    color: #34495e;
    margin-bottom: 25px;
    font-weight: 500;
    padding-left: 15px;
    border-left: 3px solid #3498db;
}

.subsection-title {
    font-size: 1.08em;
    color: #7f8c8d;
    margin: 32px 0 20px 0;
    font-weight: 500;
}

/* チェックリスト */
.checklist {
    list-style: none;
}

.checklist li {
    background-color: #fafafa;
    margin-bottom: 20px;
    padding: 20px;
    border-left: 3px solid transparent;
    border-radius: 4px;
    transition: all 0.3s ease;
}

.checklist li:hover {
    background-color: #ecf8ff;
    border-left-color: #3498db;
    box-shadow: 0 2px 8px rgba(52, 152, 219, 0.1);
}

.checklist label {
    display: flex;
    align-items: flex-start;
    cursor: pointer;
    font-weight: 400;
}

.checklist input[type="checkbox"] {
    width: 20px;
    height: 20px;
    margin-right: 15px;
    margin-top: 2px;
    cursor: pointer;
    flex-shrink: 0;
    accent-color: #3498db;
}

.item-title {
    flex: 1;
    color: #2c3e50;
    font-size: 1.02em;
}

.item-description {
    margin-top: 12px;
    padding-left: 35px;
    color: #7f8c8d;
    font-size: 0.93em;
    line-height: 1.75;
}

.checklist input[type="checkbox"]:checked + .item-title {
    text-decoration: line-through;
    color: #95a5a6;
}

/* まとめセクション */
.summary {
    background: linear-gradient(135deg, #ecf0f1 0%, #d5dbdb 100%);
    padding: 50px 40px;
    margin-top: 65px;
    border-radius: 6px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.summary h2 {
    font-size: 1.7em;
    color: #2c3e50;
    margin-bottom: 28px;
    font-weight: 400;
    text-align: center;
}

.summary p {
    margin-bottom: 18px;
    font-size: 1.02em;
    color: #34495e;
}

.save-reminder {
    font-size: 1.15em;
    text-align: center;
    margin-top: 32px;
    font-weight: 500;
    color: #2c3e50;
}

/* フッター */
footer {
    background: linear-gradient(135deg, #2c3e50 0%, #34495e 100%);
    color: #ecf0f1;
    text-align: center;
    padding: 35px;
    font-size: 0.88em;
    font-weight: 300;
    border-top: 3px solid #3498db;
}

html {
    scroll-behavior: smooth;
}

.category {
    scroll-margin-top: 20px;
}

/* レスポンシブデザイン */
@media (max-width: 768px) {
    header {
        padding: 60px 25px 50px;
    }

    header::before,
    header::after {
        display: none;
    }

    header h1 {
        font-size: 1.8em;
    }

    .subtitle {
        font-size: 0.95em;
        padding: 15px 20px;
    }

    main, .table-of-contents {
        padding-left: 25px;
        padding-right: 25px;
    }

    .category-title {
        font-size: 1.35em;
    }

    .toc-list a {
        padding: 12px 15px 12px 25px;
    }
}

@media (max-width: 480px) {
    header h1 {
        font-size: 1.5em;
    }

    .subtitle {
        font-size: 0.9em;
    }
}