/* 点击菜单外部关闭 */
        .menu-overlay {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.3);
            z-index: 1999;
            opacity: 0;
            pointer-events: none;
            transition: opacity 0.3s ease;
        }
        .menu-overlay.show {
            opacity: 1;
            pointer-events: auto;
        }

        /* 移动端菜单宽度适配 */
        @media (max-width: 480px) {
            .side-menu {
                width: 60%;
            }
        }

        @media (max-width: 480px) {
            /* 隐藏 GitHub 主页链接 */
            .locus-header .brand .custom-message {
                display: none;
            }

            /* 隐藏底部信用信息 */
            .locus-header .credit {
                display: none;
            }

            .locus-header .brand h1 {
                font-size: 18px;
            }
            .locus-header .brand .sub {
                font-size: 10px;
            }
        }

        /* 隐藏原 controls 中的按钮，因为它们已移到菜单中 */
        .controls .mode-btn,
        .controls .reset-btn,
        .controls .info-btn {
            display: none;
        }
        /* 保留 exitGoogleBtn 的显示控制 */
        .controls #exitGoogleBtn {
            display: none; 
        }
        .controls #exitGoogleBtn.visible {
            display: inline-block;
        }

        .top-btn,
        .menu-toggle {
            background: transparent;
            border: 1px solid #ddd;
            border-radius: var(--control-radius);
            width: 36px;
            height: 36px;
            font-size: 18px;
            cursor: pointer;
            transition: all 0.2s;
            display: flex;
            align-items: center;
            justify-content: center;
            flex-shrink: 0; 
            color: #333;
        }
        .top-btn:hover,
        .menu-toggle:hover {
            background: #e0e0e0;
        }

        @media (max-width: 480px) {
            .top-btn,
            .menu-toggle {
                width: 32px;
                height: 32px;
                font-size: 16px;
            }
        }

        .menu-btn.reset-in-menu,
        .menu-btn.info-in-menu {
            display: none; 
        }


                /* --- 侧滑菜单 --- */
        .side-menu {
            position: fixed;
            top: 0;
            left: 0;
            width: 300px;
            max-width: 80vw;
            height: 100vh;
            background: rgba(255, 255, 255, 0.85);
            backdrop-filter: blur(12px);
            -webkit-backdrop-filter: blur(12px);
            box-shadow: 2px 0 20px rgba(0, 0, 0, 0.15);
            z-index: 2000;
            transform: translateX(-100%);
            transition: transform 0.3s cubic-bezier(0.22, 1, 0.36, 1);
            display: flex;
            flex-direction: column;
            padding: 20px 0;
            border-right: 1px solid rgba(255,255,255,0.3);
        }

        .side-menu.open {
            transform: translateX(0);
        }

        /* 菜单头部 */
        .menu-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 0 20px 16px 20px;
            border-bottom: 1px solid #eee;
            flex-shrink: 0;
        }
        .menu-title {
            font-size: 20px;
            font-weight: 600;
            color: #1a1a1a;
        }
        .menu-header .close-btn {
            background: none;
            border: none;
            font-size: 28px;
            color: #888;
            cursor: pointer;
            padding: 0 4px;
        }

        /* 菜单列表 */
        .menu-list {
            list-style: none;
            padding: 16px 12px 20px 12px;
            margin: 0;
            flex: 1;
            overflow-y: auto;
            display: flex;
            flex-direction: column;
            gap: 8px;
        }

        .menu-list li {
            margin: 0;
            padding: 0;
        }

        .menu-btn {
            display: flex;
            align-items: center;
            justify-content: flex-start;
            width: 100%;
            padding: 12px 18px;
            background: transparent;
            border: none;
            border-radius: var(--control-radius);
            border-bottom: 1px solid #eee;
            font-size: 16px;
            font-weight: 500;
            color: #333;
            cursor: pointer;
            transition: all 0.2s ease;
            text-align: left;
            font-family: inherit;
        }
        .menu-btn:hover {
            background: rgba(255, 255, 255, 0.6);
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
        }
        .menu-btn:active {
            transform: scale(0.97);
        }
        .menu-btn.active {
            background: #d4e8ff;
            color: #0055cc;
        }
        /* 高精度建模按钮在菜单中的特殊样式 */
        .menu-btn.hd-btn {
            display: none; 
        }
        .menu-btn.hd-btn.visible {
            display: flex;
        }