:root {
        --primary-color: #26D0FF;
        --accent-color-1: #F1CE20;
        --card-bg: #ffffff;
        --text-color: #333;
        --text-color-light: #888;
        --border-color: #ebebeb;
    }
    .guestbook-container {
        max-width: 800px;
        margin: 20px auto;
        padding: 0 15px;
        background-color: transparent;
    }

    /* 留言按钮 */
    .leave-message-button-container { text-align: center; margin-bottom: 40px; }
    .leave-message-btn {
        padding: 14px 40px;
        font-size: 1em; font-weight: 600; border: none;
        border-radius: 50px; cursor: pointer; color: #fff;
        background: linear-gradient(45deg, var(--primary-color), #20F17A);
        box-shadow: 0 4px 20px rgba(38, 208, 255, 0.5);
        transition: transform 0.2s, box-shadow 0.2s;
    }
    .leave-message-btn:hover { transform: translateY(-3px); box-shadow: 0 6px 25px rgba(38, 208, 255, 0.6); }

    /* 所有留言列表 */
    .message-list-section h2 { text-align: center; margin: 40px 0 25px; font-weight: 600; }
    .message-item {
        background: var(--card-bg);
        border-radius: 16px;
        padding: 20px;
        margin-bottom: 15px;
        border: 1px solid var(--border-color);
    }
    .message-header { display: flex; align-items: center; gap: 15px; }
    .message-mood { font-size: 1.8em; }
    .message-author { font-size: 1.1em; font-weight: bold; }
    .message-footer { text-align: right; font-size: 0.8em; color: #aaa; }
    
    /********* ✨核心修改区域: 新的内容截断样式✨ *********/
    .message-content {
        margin: 10px 0;
        line-height: 1.7;
        color: var(--text-color-light);
        /* 默认只显示3行 */
        display: -webkit-box;
        -webkit-box-orient: vertical;
        -webkit-line-clamp: 3;
        overflow: hidden;
        word-break: break-all;
    }
    /* 展开后的样式 */
    .message-content.expanded {
        -webkit-line-clamp: unset; /* 取消行数限制 */
        max-height: none; /* 确保高度不被限制 */
    }
    .expand-btn {
        background: none;
        border: none;
        color: var(--primary-color);
        font-weight: bold;
        cursor: pointer;
        padding: 0;
        margin-top: 8px;
        display: block; /* 确保按钮在内容下方 */
    }
    /******************************************************/
    
    /* 模态窗口及其他样式保持不变 */
    .modal-overlay{position:fixed;top:0;left:0;width:100%;height:100%;background:rgba(0,0,0,.5);display:flex;justify-content:center;align-items:center;z-index:1000;opacity:0;visibility:hidden;transition:opacity .3s ease;backdrop-filter:blur(5px)}.modal-overlay.active{opacity:1;visibility:visible}.modal-content{background:var(--card-bg);width:90%;max-width:450px;padding:30px;border-radius:16px;transform:scale(.9);transition:transform .3s ease;position:relative}.modal-overlay.active .modal-content{transform:scale(1)}.modal-close-btn{position:absolute;top:10px;right:10px;background:#f0f0f0;border:none;border-radius:50%;width:30px;height:30px;font-size:20px;cursor:pointer;display:flex;align-items:center;justify-content:center}.captcha-group{display:flex;align-items:center;gap:10px}.captcha-group input{flex:1}.captcha-group label{font-weight:700}.error-message{color:red;text-align:center;margin-bottom:15px}.pagination{text-align:center;margin-top:30px}.pagination a,.pagination span{display:inline-block;padding:8px 16px;margin:0 5px;border:1px solid #ddd;color:var(--text-color);text-decoration:none;border-radius:8px}.pagination a:hover{background-color:#eee}.pagination .current{font-weight:700;background-color:var(--primary-color);color:#fff;border-color:var(--primary-color)}.form-modal h2{text-align:center;margin-top:0;margin-bottom:25px}.form-group{margin-bottom:20px}.form-group label{display:block;margin-bottom:8px;font-weight:600}.form-group input,.form-group textarea{width:100%;padding:12px;border:1px solid #ddd;border-radius:8px;box-sizing:border-box}.form-group input:focus,.form-group textarea:focus{outline:0;border-color:var(--primary-color);box-shadow:0 0 0 2px rgba(38,208,255,.3)}.mood-selector{display:flex;justify-content:space-around;padding:10px 0}.mood-selector input[type=radio]{display:none}.mood-selector label{font-size:2em;cursor:pointer;padding:5px;border-radius:50%;transition:transform .2s}.mood-selector input[type=radio]:checked+label{transform:scale(1.2);filter:drop-shadow(0 0 5px var(--accent-color-1))}.form-actions{text-align:center}