/* --- 一键回到最新位置悬浮按钮样式 --- */
        .scroll-down-btn {
            position: absolute;
            bottom: calc(100% + 10px);
            right: 8px;
            width: 36px;
            height: 36px;
            border-radius: 50%;
            background-color: var(--bg-surface);
            border: 1px solid var(--border-color);
            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
            display: none;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            z-index: 999;
            color: var(--text-muted);
            transition: all 0.2s ease, opacity 0.2s, transform 0.2s;
            opacity: 0;
            transform: scale(0.8);
        }
        @media (max-width: 860px) {
            .scroll-down-btn {
                left: auto;
                right: 24px;
            }
        }
        .scroll-down-btn.show {
            display: flex;
            opacity: 1;
            transform: scale(1);
        }
        .scroll-down-btn:hover {
            color: var(--text-main);
            background-color: var(--bg-hover);
            border-color: var(--text-muted);
            transform: translateY(-2px);
        }
        .scroll-down-btn svg {
            stroke-width: 2.5;
            transition: transform 0.2s ease;
        }
        .scroll-down-btn:hover svg {
            transform: translateY(1px);
        }