/* _tools/root/extract_inline_css.py が書き出した。直すときは、これを直接直してよい */
        * { margin: 0; padding: 0; box-sizing: border-box; }

        body {
            font-family: "Hiragino Mincho ProN", "BIZ UDPMincho", "Yu Mincho", YuMincho, "Noto Serif CJK JP", "Noto Serif JP", serif;
            background: linear-gradient(135deg, #0f0c29 0%, #302b63 50%, #24243e 100%);
            min-height: 100vh;
            color: #e0e0e0;
            padding: 3rem 1rem;
            line-height: 1.8;
        }

        body::before {
            content: '';
            position: fixed;
            top: 0; left: 0; width: 100%; height: 100%;
            background: radial-gradient(circle at 20% 50%, rgba(120, 119, 198, 0.15) 0%, transparent 50%),
                radial-gradient(circle at 80% 80%, rgba(255, 107, 107, 0.1) 0%, transparent 50%);
            pointer-events: none;
            z-index: 0;
        }

        .container {
            max-width: 56.25rem;
            margin: 0 auto;
            position: relative;
            z-index: 1;
            background: rgba(255, 255, 255, 0.05);
            padding: 3rem;
            border-radius: 20px;
            border: 1px solid rgba(255, 255, 255, 0.1);
            box-shadow: 0 25px 60px rgba(0, 0, 0, 0.5);
        }

        h1 {
            font-size: clamp(1.8rem, 5vw, 2.5rem);
            font-weight: 900;
            text-align: center;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
            -webkit-background-clip: text;
            background-clip: text;
            -webkit-text-fill-color: transparent;
            margin-bottom: 0.6rem;
            letter-spacing: 0.05em;
        }

        h1 a { text-decoration: none; color: inherit; }

        .lead {
            text-align: center;
            font-size: 0.98rem;
            opacity: 0.75;
            margin-bottom: 2rem;
            line-height: 1.9;
        }

        .index-list { list-style: none; padding: 0; }

        .volume-item { margin-top: 2.5rem; margin-bottom: 1.5rem; }

        .volume-title {
            font-size: 1.5rem;
            font-weight: 700;
            color: #fff;
            border-bottom: 2px solid rgba(102, 126, 234, 0.4);
            padding-bottom: 0.5rem;
            margin: 2.5rem 0 1rem;
        }

        .volume-title a { color: #fff; text-decoration: none; }
        .volume-title a:hover { text-decoration: underline; }

        .chapter-list { list-style: none; padding-left: 0.5rem; }

        .chapter-item {
            margin-bottom: 0.6rem;
            padding: 0.4rem 0;
            border-bottom: 1px solid rgba(255, 255, 255, 0.05);
        }

        .chapter-link {
            color: #e0e0e0;
            text-decoration: none;
            font-size: 1.1rem;
            font-weight: 500;
            transition: all 0.2s;
            display: inline-block;
        }

        .chapter-link:hover { color: #a5b4fc; transform: translateX(5px); }

        .section-list { list-style: none; padding-left: 1.5rem; margin-top: 0.4rem; }

        .section-item { margin-bottom: 0.2rem; }

        .section-link {
            font-size: 0.95rem;
            color: #b0c4de;
            opacity: 0.85;
            text-decoration: none;
            transition: opacity 0.2s;
        }

        .section-link:hover { opacity: 1; color: #fff; }

        .section-item.indent-1 {
            margin-left: 1.5rem;
            border-left: 1px solid rgba(255, 255, 255, 0.14);
            padding-left: 0.8rem;
            margin-top: 0.3rem;
        }

        .section-item.indent-2 {
            margin-left: 3.0rem;
            border-left: 1px solid rgba(255, 255, 255, 0.14);
            padding-left: 0.8rem;
            margin-top: 0.2rem;
        }

        .section-item.indent-3 {
            margin-left: 4.5rem;
            border-left: 1px solid rgba(255, 255, 255, 0.14);
            padding-left: 0.8rem;
            margin-top: 0.1rem;
        }

        .nav-links {
            margin-top: 4rem;
            text-align: center;
            padding-top: 2rem;
            border-top: 1px solid rgba(255, 255, 255, 0.1);
            display: flex;
            flex-wrap: wrap;
            gap: 1rem;
            justify-content: center;
        }

        .nav-links a {
            color: #fff;
            text-decoration: none;
            padding: 0.9rem 2.2rem;
            background: rgba(255, 255, 255, 0.1);
            border-radius: 50px;
            transition: all 0.3s;
            border: 1px solid rgba(255, 255, 255, 0.2);
            font-weight: 700;
            letter-spacing: 0.05em;
        }

        .nav-links a:hover {
            background: rgba(255, 255, 255, 0.15);
            transform: translateY(-3px);
            box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
        }

        details {
            margin-bottom: 1.2rem;
            background: rgba(255, 255, 255, 0.03);
            border-radius: 15px;
            overflow: hidden;
            border: 1px solid rgba(255, 255, 255, 0.05);
            transition: all 0.3s;
        }

        details[open] {
            background: rgba(255, 255, 255, 0.06);
            border-color: rgba(102, 126, 234, 0.3);
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
        }

        summary {
            padding: 1.2rem 1.8rem;
            font-size: 1.2rem;
            font-weight: 700;
            cursor: pointer;
            list-style: none;
            display: flex;
            justify-content: space-between;
            align-items: center;
            gap: 1rem;
            color: #fff;
            transition: background 0.2s;
        }

        summary:hover { background: rgba(255, 255, 255, 0.05); }

        summary::-webkit-details-marker { display: none; }

        summary::after {
            content: '＋';
            font-size: 1.1rem;
            color: #667eea;
            transition: transform 0.3s;
            flex: 0 0 auto;
        }

        details[open] summary::after { content: '－'; transform: rotate(180deg); }

        .details-content {
            padding: 0 1.8rem 1.5rem;
            border-top: 1px solid rgba(255, 255, 255, 0.05);
            margin-top: 0;
        }

        .details-content .chapter-item { border-bottom: 1px solid rgba(255, 255, 255, 0.03); }
        .details-content .chapter-item:last-child { border-bottom: none; }

        .read-chapter { margin: 1rem 0 1.2rem; }

        .read-chapter a {
            font-size: 1.05rem;
            border-bottom: 1px solid rgba(255, 255, 255, 0.2);
        }

        .source-note {
            margin-top: 2.5rem;
            font-size: 0.9rem;
            line-height: 1.9;
            opacity: 0.7;
        }

        @media (max-width: 767px) {
            body { padding: 1.5rem 0.6rem; }
            .container { padding: 1.5rem 1rem; }
            summary { padding: 1rem 1.1rem; font-size: 1.05rem; }
            .details-content { padding: 0 0.7rem 1rem; }
        }