/* ===== 口算专用样式 ===== */
        .grade-tabs {
            display: flex;
            flex-wrap: wrap;
            gap: 0.6rem;
            margin-bottom: 1.5rem;
            justify-content: center;
        }
        .grade-tab {
            padding: 0.5rem 1.5rem;
            border-radius: 60px;
            border: 2px solid rgba(66, 165, 245, 0.2);
            background: rgba(255, 255, 255, 0.6);
            font-weight: 700;
            font-size: 0.95rem;
            color: #0d2b3e;
            cursor: pointer;
            transition: all 0.2s;
            font-family: 'Quicksand', 'Microsoft YaHei', sans-serif;
        }
        .grade-tab:hover {
            background: rgba(66, 165, 245, 0.08);
            border-color: #42a5f5;
        }
        .grade-tab.active {
            background: #42a5f5;
            color: white;
            border-color: #1e88e5;
            box-shadow: 0 4px 0 #1e88e5;
        }
        .grade-tab .grade-icon {
            margin-right: 6px;
        }

        .hidden {
            display: none !important;
        }

        /* 练习区域 */
        .problem-display {
            text-align: center;
            padding: 2rem 1rem;
        }
        .question-text {
            font-size: 2.4rem;
            font-weight: 700;
            color: #0d2b3e;
            font-family: 'Quicksand', 'Microsoft YaHei', sans-serif;
            letter-spacing: 2px;
            min-height: 4rem;
        }
        .question-number-hint {
            font-size: 0.95rem;
            color: #1e88e5;
            font-weight: 600;
            margin-top: 0.5rem;
        }

        .input-area {
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 0.8rem;
            margin: 1.5rem auto;
            max-width: 320px;
            width: 100%;
        }
        .input-area input[type="number"] {
            width: 200px;
            padding: 0.7rem 1.2rem;
            border-radius: 60px;
            border: 2px solid rgba(66, 165, 245, 0.2);
            font-size: 1.2rem;
            font-weight: 600;
            font-family: 'Quicksand', 'Microsoft YaHei', sans-serif;
            text-align: center;
            outline: none;
            transition: 0.15s;
        }
        .input-area input[type="number"]:focus {
            border-color: #42a5f5;
            box-shadow: 0 0 0 3px rgba(66, 165, 245, 0.15);
        }
        .input-area input[type="number"]::-webkit-inner-spin-button {
            opacity: 1;
        }

        .feedback-text {
            text-align: center;
            font-size: 1.2rem;
            font-weight: 700;
            min-height: 2.8rem;
            padding: 0.4rem;
        }
        .feedback-text.correct {
            color: #27ae60;
        }
        .feedback-text.wrong {
            color: #e74c3c;
        }

        /* 进度条 */
        .progress-wrapper {
            margin: 1.2rem 0 1.8rem;
        }
        .progress-track {
            width: 100%;
            height: 10px;
            background: rgba(66, 165, 245, 0.15);
            border-radius: 20px;
            overflow: hidden;
            border: 1px solid rgba(66, 165, 245, 0.1);
        }
        .progress-fill {
            height: 100%;
            width: 0%;
            background: linear-gradient(90deg, #42a5f5, #66bb6a);
            border-radius: 20px;
            transition: width 0.3s ease;
        }

        /* 统计行 */
        .stats-row {
            display: flex;
            flex-wrap: wrap;
            justify-content: center;
            gap: 1.5rem 2.5rem;
            padding: 0.8rem 1rem;
            background: rgba(225, 245, 254, 0.3);
            border-radius: 60px;
            border: 1px solid rgba(66, 165, 245, 0.1);
        }
        .stat-item {
            font-weight: 600;
            color: #0d2b3e;
            font-size: 0.95rem;
        }
        .stat-item i {
            color: #42a5f5;
            margin-right: 4px;
        }
        .stat-value {
            color: #0d2b3e;
            font-weight: 700;
        }

        /* 结果区域 */
        .result-card {
            text-align: center;
            padding: 1rem 0.5rem;
        }
        .big-icon {
            font-size: 4rem;
            display: block;
            margin-bottom: 0.5rem;
        }
        .result-card h2 {
            font-size: 1.8rem;
            color: #0d2b3e;
            margin-bottom: 0.8rem;
        }
        .result-stats {
            background: rgba(255, 255, 255, 0.6);
            border-radius: 30px;
            padding: 1.2rem 2rem;
            max-width: 500px;
            margin: 0 auto;
            text-align: left;
            font-size: 1rem;
            line-height: 1.8;
            border: 1px solid rgba(66, 165, 245, 0.1);
        }
        .result-stats .stat-label {
            font-weight: 600;
            color: #0d2b3e;
        }
        .result-stats .stat-value {
            color: #1e88e5;
            font-weight: 700;
        }
        .result-stats hr {
            border: none;
            border-top: 1px solid rgba(66, 165, 245, 0.15);
            margin: 6px 0;
        }

        .wrong-list {
            max-width: 600px;
            margin: 1.5rem auto 0;
            text-align: left;
        }
        .wrong-list h3 {
            font-size: 1.1rem;
            color: #e74c3c;
            margin-bottom: 0.8rem;
            text-align: center;
        }
        .wrong-list table {
            width: 100%;
            border-collapse: collapse;
            font-size: 0.9rem;
            border-radius: 16px;
            overflow: hidden;
            border: 1px solid rgba(66, 165, 245, 0.1);
        }
        .wrong-list th {
            background: rgba(66, 165, 245, 0.08);
            font-weight: 700;
            color: #0d2b3e;
            padding: 0.5rem 0.8rem;
            text-align: center;
        }
        .wrong-list td {
            padding: 0.4rem 0.8rem;
            text-align: center;
            border-bottom: 1px solid rgba(66, 165, 245, 0.05);
        }
        .wrong-list .correct-answer {
            color: #27ae60;
            font-weight: 700;
        }
        .wrong-list .wrong-answer {
            color: #e74c3c;
            font-weight: 700;
        }

        /* 今日统计小标签 */
        .daily-stats-bar {
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            justify-content: center;
            gap: 0.8rem 1.8rem;
            padding: 0.4rem 1.5rem;
            background: rgba(243, 156, 18, 0.08);
            border-radius: 60px;
            border: 1px solid rgba(243, 156, 18, 0.15);
            font-size: 0.85rem;
            font-weight: 600;
            color: #7d6608;
            margin-bottom: 1.2rem;
        }
        .daily-stats-bar .label {
            color: #0d2b3e;
        }
        .daily-stats-bar .value {
            color: #e67e22;
            font-weight: 700;
        }
        .daily-stats-bar .value.maxed {
            color: #e74c3c;
        }
        .daily-stats-bar .divider {
            color: #ddd;
        }

        @media (max-width: 768px) {
            .question-text {
                font-size: 1.8rem;
            }
            .input-area input[type="number"] {
                width: 160px;
                font-size: 1rem;
            }
            .grade-tab {
                font-size: 0.8rem;
                padding: 0.35rem 1rem;
            }
            .result-stats {
                padding: 1rem 1.2rem;
                font-size: 0.9rem;
            }
            .stats-row {
                gap: 0.8rem 1.2rem;
                font-size: 0.85rem;
            }
            .daily-stats-bar {
                font-size: 0.75rem;
                gap: 0.4rem 1rem;
                padding: 0.5rem 1rem;
            }
        }

        @media print {
            .grade-tabs, .config-panel, .btn-group,
            .tool-nav, .breadcrumb, .header, .footer,
            .donation-section, .daily-stats-bar {
                display: none !important;
            }
            .main-card {
                box-shadow: none !important;
                border: none !important;
                padding: 0 !important;
            }
            .questions-container {
                column-count: 2;
            }
            .question-item {
                border: none !important;
                border-bottom: 1px dashed #ccc !important;
            }
            .answer {
                display: none !important;
            }
        }