body {
        margin: 0;
        font-family: var(--font-stack);
        background-color: var(--dark-bg);
        background-image: linear-gradient(rgba(93, 64, 55, 0.1) 1px, transparent 1px),
                          linear-gradient(90deg, rgba(93, 64, 55, 0.1) 1px, transparent 1px);
        background-size: 40px 40px;
        color: var(--text);
        display: flex;
        flex-direction: column;
        align-items: center;
        min-height: 100vh;
        padding-bottom: 100px;
        -webkit-tap-highlight-color: transparent;
        touch-action: manipulation;
    }

    h1 {
        margin-top: 20px;
        font-size: clamp(1.2rem, 5vw, 2.2rem);
        color: var(--secondary);
        text-shadow: 0 0 10px rgba(104, 159, 56, 0.5);
        text-align: center;
        text-transform: uppercase;
        white-space: nowrap;
        width: 100%;
        overflow: hidden;
        text-overflow: ellipsis;
        padding: 0 10px;
        box-sizing: border-box;
        user-select: none;
        -webkit-user-select: none;
    }

    /* --- Tab 导航栏 --- */
    .tab-container {
        width: 95%;
        max-width: 600px;
        display: flex;
        justify-content: space-around;
        background: rgba(30, 30, 30, 0.9);
        border-radius: 50px;
        padding: 5px;
        margin-top: 20px;
        border: 1px solid var(--primary);
    }

    .tab-btn {
        flex: 1;
        padding: 12px 0;
        background: transparent;
        border: none;
        color: #9e9e9e;
        font-size: 1rem;
        font-weight: bold;
        cursor: pointer;
        border-radius: 40px;
        transition: all 0.3s;
        user-select: none;
        -webkit-user-select: none;
    }

    .tab-btn.active {
        background: var(--secondary);
        color: #fff;
        box-shadow: 0 0 15px rgba(104, 159, 56, 0.4);
    }

    /* --- 启动菜单 --- */
    #start-screen {
        display: flex; flex-direction: column; gap: 15px;
        width: 90%; max-width: 450px; margin-top: 30px;
        transition: opacity 0.3s;
    }

    .no-data-msg {
        text-align: center;
        color: #8b949e;
        margin-top: 50px;
        font-size: 1.2rem;
        border: 1px dashed var(--secondary);
        padding: 40px;
        border-radius: 15px;
    }

    .mode-btn {
        padding: 18px; font-size: 1.1rem;
        border: 2px solid var(--primary);
        background: rgba(93, 64, 55, 0.2); color: var(--text);
        border-radius: 12px; cursor: pointer;
        display: flex; align-items: center; justify-content: space-between;
        transition: transform 0.1s;
        user-select: none; -webkit-user-select: none;
    }
    .mode-btn:active { transform: scale(0.98); background: var(--primary); color: #fff; }
    
    .mode-btn.list-mode { border-color: var(--secondary); background: rgba(104, 159, 56, 0.2); }
    .mode-btn.list-mode:active { background: var(--secondary); color: #fff; }

    .mode-btn.text-mode { border-color: var(--accent); background: rgba(255, 87, 34, 0.2); }
    .mode-btn.text-mode:active { background: var(--accent); color: #fff; }

    .mode-icon { font-size: 1.4rem; }

    /* --- 舞台通用 --- */
    .stage {
        display: none; 
        width: 95%; flex-direction: column;
        align-items: center; 
        margin-top: 20px;
    }
    
    #game-stage { max-width: 600px; }
    #list-stage { max-width: 800px; } 
    #text-stage { max-width: 800px; }

    /* --- 闪卡布局 (初中生版) --- */
    .flashcard-container { perspective: 1000px; width: 100%; height: 500px; margin-bottom: 20px; }
    .flashcard { position: relative; width: 100%; height: 100%; text-align: center; transition: transform 0.6s; transform-style: preserve-3d; }
    .flashcard.flipped { transform: rotateY(180deg); }
    
    .card-face {
        position: absolute; width: 100%; height: 100%; backface-visibility: hidden;
        display: flex; 
        flex-direction: column; 
        align-items: center; 
        /* 垂直居中对齐 */
        justify-content: center;
        border-radius: 20px; border: 2px solid var(--secondary);
        background: linear-gradient(145deg, #2c2c2c, #1a1a1a); 
        padding: 25px 15px; box-sizing: border-box;
        overflow-y: auto;
    }
    .card-back { background: linear-gradient(145deg, #3e2723, #211a18); transform: rotateY(180deg); border-color: var(--accent); }
    
    .card-header-word { font-size: 2.2rem; font-weight: bold; color: var(--secondary); margin-bottom: 2px; margin-top: 0; line-height: 1.35; width:100%; border-bottom: 1px solid rgba(255,255,255,0.1);}
    .card-cn-meaning { font-size: 1.5rem; color: var(--accent); font-weight: bold; margin-bottom: 10px; margin-top: 10px; border-bottom: 1px solid rgba(255,255,255,0.1); padding-bottom: 10px; width: 90%; }
    
    .sentence-box { font-size: 1rem; color: #ccc; background: rgba(255,255,255,0.05); padding: 12px; border-radius: 8px; width: 95%; text-align: left; margin-bottom: 10px; border-left: 3px solid var(--secondary); }
    .sentence-label { font-size: 0.8rem; color: #888; display: block; margin-bottom: 4px; }
    
    .expansion-box { font-size: 0.95rem; color: #DCEDC8; background: rgba(104, 159, 56, 0.1); padding: 12px; border-radius: 8px; width: 95%; text-align: left; border: 1px dashed var(--secondary); margin-top: 5px; }
    .expansion-title { color: var(--secondary); font-weight: bold; font-size: 0.9rem; display: block; margin-bottom: 5px; }

    .clickable-box { cursor: pointer; transition: all 0.2s; border: 1px solid transparent; }
    .clickable-box:hover { background-color: rgba(255, 193, 7, 0.15); border-color: rgba(255, 193, 7, 0.3); color: #fff; }

    .btn-speak-lg { background: rgba(104, 159, 56, 0.15); border: 2px solid var(--secondary); color: var(--secondary); border-radius: 50%; width: 60px; height: 60px; cursor: pointer; font-size: 1.5rem; flex-shrink: 0; user-select: none; margin-top: 15px; }

    /* 正面提示控制区样式 */
    .hint-controls { margin-top: 15px; display: flex; gap: 10px; justify-content: center; width: 100%; }
    .hint-btn { background: transparent; border: 1px solid var(--primary); color: #aaa; padding: 6px 12px; border-radius: 20px; font-size: 0.85rem; cursor: pointer; transition: all 0.2s; }
    .hint-btn:hover { background: rgba(255, 255, 255, 0.1); color: #fff; border-color: var(--secondary); }
    
    .front-hint-text { margin-top: 15px; font-size: 1rem; color: #AED581; font-style: italic; background: rgba(0, 0, 0, 0.3); padding: 10px; border-radius: 8px; width: 90%; text-align: center; display: none; border: 1px dashed var(--secondary); }

    /* --- 弹窗 (Popup/Modal) 样式 --- */
    .modal-overlay {
        position: fixed; top: 0; left: 0; width: 100%; height: 100%;
        background: rgba(0, 0, 0, 0.85);
        z-index: 2000;
        display: none;
        justify-content: center;
        align-items: center;
        backdrop-filter: blur(5px);
    }
    .modal-card {
        background: linear-gradient(145deg, #2c2c2c, #1a1a1a);
        width: 90%; max-width: 500px; max-height: 80vh;
        border-radius: 20px;
        border: 2px solid var(--secondary);
        padding: 25px;
        box-shadow: 0 10px 30px rgba(0,0,0,0.5);
        position: relative;
        overflow-y: auto;
        text-align: center;
        animation: popIn 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    }
    @keyframes popIn { from { transform: scale(0.8); opacity: 0; } to { transform: scale(1); opacity: 1; } }
    
    .modal-close-btn {
        position: absolute; top: 10px; right: 15px;
        background: none; border: none; color: #888; font-size: 2rem; cursor: pointer;
        line-height: 1; z-index: 10;
    }
    .modal-close-btn:hover { color: #fff; }

    /* --- 底部控制栏 --- */
/*
    .bottom-bar { position: fixed; bottom: 0; left: 0; width: 100%; background: rgba(18, 18, 18, 0.95); border-top: 1px solid var(--primary); padding: 15px; display: flex; justify-content: center; gap: 20px; box-shadow: 0 -5px 20px rgba(0,0,0,0.5); z-index: 100; backdrop-filter: blur(10px); padding-bottom: env(safe-area-inset-bottom, 20px); }
    .return-btn { padding: 12px 20px; border-radius: 50px; border: 1px solid #555; background: transparent; color: #aaa; cursor: pointer; user-select: none; -webkit-user-select: none; }
*/
/* 新版.bottom-bar、 .return-btn修复底部返回主菜单按钮布局中的问题*/
    .bottom-bar {
        /* 基础布局 */
        position: fixed;
        bottom: 0;
        left: 0;
        width: 100%;
        box-sizing: border-box; /* 解决不居中的核心 */
        
        /* 居中对齐 */
        display: flex;
        justify-content: center;
        align-items: center;
        
        /* 间距与外观 */
        padding: 15px;
        padding-bottom: env(safe-area-inset-bottom, 20px);
        background: rgba(13, 17, 23, 0.95);
        border-top: 1px solid #30363d; /* 假设的变量颜色 */
        backdrop-filter: blur(10px);
        z-index: 100;
    }
    
    .return-btn {
        margin: 0; /* 清除默认外边距 */
        padding: 12px 20px;
        border-radius: 50px;
        border: 1px solid #555;
        background: transparent;
        color: #aaa;
        cursor: pointer;
    }

    .play-btn { padding: 12px 30px; border-radius: 50px; font-size: 1.1rem; border: none; font-weight: bold; cursor: pointer; box-shadow: 0 4px 10px rgba(0,0,0,0.3); transition: all 0.2s; min-width: 140px; user-select: none; -webkit-user-select: none; }
    .play-btn.start { background: var(--secondary); color: #fff; }
    .play-btn.stop { background: #d32f2f; color: #fff; }
    .controls { display: flex; gap: 20px; width: 100%; justify-content: center; margin-top: 10px;}
    .nav-btn { padding: 12px 25px; border: 1px solid var(--text); background: rgba(255,255,255,0.05); color: var(--text); border-radius: 8px; cursor: pointer; user-select: none; }

    /* --- 列表与阅读通用样式 --- */
    .active-highlight { background-color: rgba(104, 159, 56, 0.2) !important; border-left: 5px solid #FFC107 !important; color: #fff !important; }
    
    .table-wrapper { width: 100%; overflow-x: auto; background: rgba(30, 30, 30, 0.9); border-radius: 12px; border: 1px solid var(--primary); }

    /*修改单词列表的字体大小（除例句大小，例句大小调整调整.sent-cell）*/
    table { width: 100%; border-collapse: collapse; min-width: 350px; font-size: 1.0rem; } 
    
    th { padding: 12px 15px; text-align: left; background: rgba(93, 64, 55, 0.4); color: #fff; position: sticky; top: 0; z-index: 10; white-space: nowrap; }
    
    td { padding: 8px 15px; text-align: left; vertical-align: top; }
    
    .row-main td { border-bottom: none; padding-bottom: 2px; }
    .row-sent td { border-bottom: 1px solid rgba(255,255,255,0.1); padding-top: 0; padding-bottom: 12px; }
    
    /*单词列表中的column宽度调整 col-id主要靠调整padding-left和padding-right;*/
    .col-id { width: 40px; color: #8b949e; text-align: center; vertical-align: middle; border-bottom: 1px solid rgba(255,255,255,0.1); padding-left: 5px; padding-right: 5px;}    
    .col-word { width: 45%; color: var(--secondary); font-weight: bold; padding-left: 3px;} /*use padding-left to move the 'English' column all the way left to save space*/
    .col-cn { width: 55%; color: #ccc; }
    
    /*单词列表中的例句字体大小*/
    .sent-cell { color: #AED581; font-style: italic; font-size: 0.95rem; }

    /* 单词链接样式 */
    .word-link {
        color: var(--secondary);
        text-decoration: underline;
        text-decoration-color: rgba(104, 159, 56, 0.5);
        cursor: pointer;
        transition: color 0.2s;
    }
    .word-link:hover {
        color: #fff;
        text-decoration-color: #fff;
    }

    .mini-btn_old { background: none; border: 1px solid var(--secondary); color: var(--secondary); border-radius: 50%; width: 24px; height: 24px; cursor: pointer; margin-right: 8px; flex-shrink: 0; }
    .mini-btn {
        background: none; border: 1px solid var(--secondary); color: var(--secondary);
        border-radius: 50%; width: 28px; height: 28px; cursor: pointer;
        display: inline-flex; align-items: center; justify-content: center; 
        margin-right: 8px; margin-left: 0;
        flex-shrink: 0;
        user-select: none; -webkit-user-select: none;
    }    
    
    .text-container { width: 100%; background: rgba(30, 30, 30, 0.8); border-radius: 15px; padding: 20px; box-sizing: border-box; border: 1px solid var(--primary); margin-bottom: 80px; }
    .paragraph-box { margin-bottom: 30px; padding-bottom: 20px; border-bottom: 1px dashed rgba(255, 255, 255, 0.1); }
    .para-en-container { font-size: 1.3rem; line-height: 1.8; margin-bottom: 15px; }
    .clickable-sentence { cursor: pointer; padding: 4px 6px; border-radius: 4px; display: inline-block; transition: background-color 0.2s; }
    .clickable-sentence:hover { background-color: rgba(255, 193, 7, 0.2); color: #FFC107; }
    .para-cn { font-size: 1rem; color: #9e9e9e; background: rgba(0,0,0,0.2); padding: 10px; border-radius: 8px; }
    .pos-tag {
        font-size: 0.8em; color: #8b949e; font-weight: normal; margin-right: 8px; margin-bottom: 3px; 
        background: rgba(255,255,255,0.1); padding: 2px 6px; border-radius: 4px;
        /*margin-top: 10px;*/
    }