* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Microsoft YaHei', '微软雅黑', Arial, sans-serif;
    background: #f5f5f5;
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    background: white;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    overflow: hidden;
}

.header {
    background: #4a90e2;
    color: white;
    padding: 30px;
    text-align: center;
}

.header h1 {
    font-size: 2.2em;
    margin-bottom: 10px;
    font-weight: 500;
}

.header p {
    font-size: 1em;
    opacity: 0.95;
}

.content {
    padding: 30px;
}

.config-section {
    background: #fafafa;
    border: 1px solid #e0e0e0;
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 30px;
}

.config-section h2 {
    color: #333;
    margin-bottom: 15px;
    font-size: 1.3em;
    font-weight: 500;
}

.input-group {
    margin-bottom: 15px;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    color: #333;
    font-weight: bold;
    font-size: 1.1em;
}

.input-group input {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 1em;
    transition: all 0.3s;
}

.input-group input:focus {
    outline: none;
    border-color: #4a90e2;
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.1);
}

.btn {
    background: #4a90e2;
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 6px;
    font-size: 1em;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
}

.btn:hover {
    background: #357abd;
}

.btn:active {
    background: #2a6ba0;
}

.btn-success {
    background: #52c41a;
}

.btn-success:hover {
    background: #45a016;
}

.btn-primary {
    background: #4a90e2;
}

.btn-primary:hover {
    background: #357abd;
}

.selection-section {
    background: #fafafa;
    border: 1px solid #e0e0e0;
    border-radius: 8px;
    padding: 25px;
    margin-bottom: 30px;
}

.selection-section h2 {
    color: #333;
    margin-bottom: 20px;
    font-size: 1.3em;
    font-weight: 500;
}

.selection-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
}

.select-group {
    text-align: left;
}

.select-group label {
    display: block;
    margin-bottom: 8px;
    color: #333;
    font-weight: 500;
    font-size: 1em;
}

.select-group select {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 1em;
    background: white;
    cursor: pointer;
    transition: all 0.3s;
}

.select-group select:focus {
    outline: none;
    border-color: #4a90e2;
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.1);
}

.exercise-section {
    background: #fafafa;
    border: 1px solid #e0e0e0;
    border-radius: 8px;
    padding: 25px;
    min-height: 200px;
}

.exercise-section h2 {
    color: #333;
    margin-bottom: 20px;
    font-size: 1.3em;
    font-weight: 500;
}

.exercise-content {
    background: white;
    border-radius: 8px;
    padding: 15px;
    min-height: 150px;
    text-align: left;
    white-space: pre-wrap;
    line-height: 1.4;
    font-size: 1em;
    color: #333;
}

.loading {
    text-align: center;
    padding: 40px;
    color: #666;
    font-size: 1.2em;
}

.loading::after {
    content: '...';
    animation: dots 1.5s steps(4, end) infinite;
}

@keyframes dots {
    0%, 20% { content: '.'; }
    40% { content: '..'; }
    60%, 100% { content: '...'; }
}

.status-message {
    padding: 15px;
    border-radius: 10px;
    margin-bottom: 20px;
    font-weight: bold;
}

.status-success {
    background: #f6ffed;
    color: #389e0d;
    border: 1px solid #b7eb8f;
}

.status-error {
    background: #fff2f0;
    color: #cf1322;
    border: 1px solid #ffccc7;
}

.status-info {
    background: #e6f7ff;
    color: #0958d9;
    border: 1px solid #91d5ff;
}

.hidden {
    display: none;
}

.btn-group {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.btn-group .btn {
    flex: 1;
    min-width: 150px;
}

.question-item {
    margin-bottom: 10px;
    padding: 10px;
    background: #fff;
    border-radius: 6px;
    border: 1px solid #e0e0e0;
}

.question-text {
    font-size: 1em;
    margin-bottom: 6px;
    color: #333;
    font-weight: 500;
    line-height: 1.3;
}

.answer-input-group {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-top: 6px;
}

.answer-input-group label {
    font-weight: 500;
    color: #666;
    min-width: 50px;
    font-size: 0.95em;
}

.answer-input-group input {
    flex: 1;
    padding: 6px 10px;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 0.95em;
}

.answer-input-group input:focus {
    outline: none;
    border-color: #4a90e2;
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.1);
}

.answer-result {
    margin-top: 5px;
    padding: 5px 10px;
    border-radius: 4px;
    font-size: 0.9em;
}

.answer-correct {
    background: #f6ffed;
    color: #389e0d;
    border: 1px solid #b7eb8f;
}

.answer-wrong {
    background: #fff2f0;
    color: #cf1322;
    border: 1px solid #ffccc7;
}

.answer-standard {
    background: #e6f7ff;
    color: #0958d9;
    border: 1px solid #91d5ff;
    margin-top: 5px;
}

.standard-answer {
    display: none;
    margin-top: 5px;
    padding: 5px 10px;
    background: #f0f0f0;
    border-radius: 4px;
    color: #666;
    font-size: 0.9em;
}

.standard-answer.show {
    display: block;
}

.menu-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-top: 30px;
}

.menu-card {
    background: #fafafa;
    border: 1px solid #e0e0e0;
    border-radius: 8px;
    padding: 30px;
    text-align: center;
    transition: all 0.3s;
    cursor: pointer;
    text-decoration: none;
    color: inherit;
    display: block;
}

.menu-card:hover {
    background: #f0f0f0;
    border-color: #4a90e2;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.menu-card h3 {
    font-size: 1.5em;
    margin-bottom: 10px;
    color: #333;
}

.menu-card p {
    color: #666;
    font-size: 0.95em;
}

.nav-bar {
    background: #fafafa;
    border-bottom: 1px solid #e0e0e0;
    padding: 15px 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-bar a {
    color: #4a90e2;
    text-decoration: none;
    font-weight: 500;
}

.nav-bar a:hover {
    text-decoration: underline;
}