/* カスタムスタイル */
        body {
            color: #404040;
            line-height: 1.8;
            background-color: #ffffff;
            -webkit-font-smoothing: antialiased;
        }
        h1, h2, h3, h4, h5, h6 {
            color: #171717;
            font-weight: 700;
            line-height: 1.4;
            letter-spacing: 0.05em;
        }
        html { scroll-behavior: smooth; }
        
        .section-padding {
            padding-top: 6rem;
            padding-bottom: 6rem;
        }
        @media (min-width: 1024px) {
            .section-padding {
                padding-top: 8rem;
                padding-bottom: 8rem;
            }
        }

        /* 追従ヘッダー */
        #sticky-header {
            transform: translateY(-100%);
            transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1);
        }
        #sticky-header.is-visible {
            transform: translateY(0);
        }

        /* アニメーション */
        .fade-in-up {
            opacity: 0;
            transform: translateY(30px);
            transition: opacity 0.8s cubic-bezier(0.16, 1, 0.3, 1), transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
        }
        .fade-in-up.visible {
            opacity: 1;
            transform: translateY(0);
        }

        /* アコーディオン（details/summary）のスタイル調整 */
        details > summary {
            list-style: none;
            cursor: pointer;
        }
        details > summary::-webkit-details-marker {
            display: none;
        }
        details[open] summary ~ * {
            animation: slideDown 0.3s ease-in-out;
        }
        @keyframes slideDown {
            from { opacity: 0; transform: translateY(-10px); }
            to { opacity: 1; transform: translateY(0); }
        }