* { 
            margin: 0; 
            padding: 0; 
            box-sizing: border-box; 
            font-family: 微软雅黑; 
            outline: none;
            -webkit-tap-highlight-color: transparent;
        }
        input, textarea, button, div, img {
            outline: none;
        }
        button, div, img {
            -webkit-user-select: none;
            user-select: none;
        }
        button, input[type="submit"] {
            border: none;
            cursor: pointer;
        }
        .container { max-width: 800px; margin: 50px auto; padding: 0 20px; }
        .form-item { margin-bottom: 30px; }
        label { display: block; font-size: 18px; margin-bottom: 10px; color: #333; }
        #question-input { 
            width: 100%; 
            padding: 15px; 
            border: 1px solid #ddd; 
            border-radius: 8px; 
            font-size: 16px; 
            resize: vertical; 
            min-height: 150px; 
            -webkit-user-select: text;
            user-select: text;
        }
        .upload-btn { 
            padding: 12px 24px; 
            background: #409eff; 
            color: white; 
            border-radius: 8px; 
            font-size: 16px; 
            display: inline-block;
        }
        .upload-btn:hover { background: #2684ff; }
        #img-upload { display: none; }
        .img-preview { display: flex; gap: 15px; flex-wrap: wrap; margin-top: 15px; }
        .preview-item { 
            width: 120px; 
            height: 120px; 
            border: 1px dashed #ddd; 
            border-radius: 8px; 
            overflow: hidden; 
            position: relative; 
            display: flex; /* 优化1：图片加载前居中占位 */
            align-items: center;
            justify-content: center;
            color: #999;
            font-size: 12px;
        }
        .preview-item img { 
            width: 100%; 
            height: 100%; 
            object-fit: cover; 
            position: absolute; /* 优化1：图片覆盖占位文字 */
            top: 0;
            left: 0;
        }
        .preview-item .del-img { 
            position: absolute; 
            top: 5px; 
            right: 5px; 
            width: 24px; 
            height: 24px; 
            background: rgba(0,0,0,0.5); 
            color: white; 
            border-radius: 50%; 
            text-align: center; 
            line-height: 24px; 
            cursor: pointer; 
            display: none; 
            z-index: 10; /* 优化2：确保删除按钮在最上层 */
        }
        .preview-item:hover .del-img { display: block; }
        .verify-box { display: flex; align-items: center; gap: 15px; }
        #verify-code { 
            width: 100%; 
            padding: 15px; 
            border: 1px solid #ddd; 
            border-radius: 8px; 
            font-size: 16px; 
            -webkit-user-select: text;
            user-select: text;
        }
        .verify-code-img { 
            width: 120px; 
            height: 50px; 
            background: #f5f5f5; 
            border-radius: 8px; 
            display: flex; 
            align-items: center; 
            justify-content: center; 
            font-size: 24px; 
            font-weight: bold; 
            color: #333; 
            cursor: pointer; 
            letter-spacing: 5px; 
            user-select: none; /* 优化3：禁止选中验证码文字 */
        }
        input[type="submit"] { 
            width: 100%; 
            padding: 16px; 
            background: #2ecc71; 
            color: white; 
            border-radius: 8px; 
            font-size: 18px; 
            margin-top: 20px; 
            transition: background 0.3s; /* 优化：加 hover 过渡动画 */
        }
        input[type="submit"]:hover { 
            background: #27ae60; /* 优化：hover 加深颜色 */
        }
        input[type="submit"]:disabled { 
            background: #bdc3c7; 
            cursor: not-allowed; 
            transform: none; /* 禁用时取消过渡 */
        }
        .tips { margin-top: 15px; font-size: 14px; color: #666; }
        .success { color: #2ecc71; font-size: 16px; margin-top: 20px; font-weight: bold; }
        .error { color: #e74c3c; font-size: 16px; margin-top: 20px; font-weight: bold; }
        #verify-code-hidden { display: none; }