/* 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Arial', sans-serif;
    background-color: #f5f5f5;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    background-color: #fff;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    min-height: 80vh;
    border-radius: 8px;
    margin-top: 20px;
    margin-bottom: 20px;
}

/* 头部样式 */
header {
    background-color: #4CAF50;
    color: white;
    padding: 15px;
    text-align: center;
    border-radius: 8px 8px 0 0;
    margin: -20px -20px 20px -20px;
}

header h1 {
    margin: 0;
    font-size: 24px;
}

nav {
    background-color: #333;
    color: white;
    padding: 10px;
    margin: -20px -20px 20px -20px;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    gap: 20px;
}

nav ul li a {
    color: white;
    text-decoration: none;
    padding: 5px 10px;
    border-radius: 4px;
    transition: background-color 0.3s;
}

nav ul li a:hover {
    background-color: #555;
}

/* 登录页面样式 */
.login-container {
    max-width: 400px;
    margin: 50px auto;
    padding: 30px;
    background-color: #fff;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    border-radius: 8px;
}

.login-container h2 {
    text-align: center;
    margin-bottom: 20px;
    color: #4CAF50;
}

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

.form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
}

.form-group input {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 16px;
}

.btn {
    display: inline-block;
    padding: 10px 20px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.3s;
}

.btn:hover {
    background-color: #45a049;
}

.btn-block {
    width: 100%;
    margin-top: 10px;
}

.error-message {
    color: #f44336;
    margin-top: 10px;
    text-align: center;
}

/* 每日一题样式 */
.question-container {
    background-color: #f9f9f9;
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 20px;
}

.question-content {
    margin-bottom: 20px;
}

.question-content h3 {
    margin-bottom: 10px;
    color: #4CAF50;
}

.question-image {
    max-width: 100%;
    height: auto;
    border-radius: 4px;
    margin: 10px 0;
}

.options {
    margin: 20px 0;
}

.option {
    display: block;
    padding: 10px;
    margin-bottom: 10px;
    background-color: #fff;
    border: 1px solid #ddd;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.3s;
}

.option:hover {
    background-color: #f0f0f0;
}

.option.selected {
    background-color: #e3f2fd;
    border-color: #2196F3;
}

.option.correct {
    background-color: #e8f5e8;
    border-color: #4CAF50;
}

.option.incorrect {
    background-color: #ffebee;
    border-color: #f44336;
}

.explanation {
    background-color: #fff3e0;
    padding: 15px;
    border-radius: 4px;
    margin-top: 20px;
    border-left: 4px solid #ff9800;
}

/* 历史题目样式 */
.history-container {
    margin-top: 20px;
}

.history-item {
    background-color: #f9f9f9;
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 15px;
    border-left: 4px solid #2196F3;
}

.history-item.correct {
    border-left-color: #4CAF50;
}

.history-item.incorrect {
    border-left-color: #f44336;
}

.history-item h4 {
    margin-bottom: 10px;
}

.history-item .meta {
    font-size: 12px;
    color: #666;
    margin-top: 10px;
}

/* 个人中心样式 */
.profile-container {
    margin-top: 20px;
}

.score-card {
    background-color: #e3f2fd;
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 20px;
    text-align: center;
}

.score-card h3 {
    color: #2196F3;
    margin-bottom: 10px;
}

.score-value {
    font-size: 36px;
    font-weight: bold;
    color: #1976D2;
}

.user-info {
    background-color: #f9f9f9;
    padding: 20px;
    border-radius: 8px;
}

.user-info h3 {
    margin-bottom: 15px;
    color: #4CAF50;
}

.user-info p {
    margin-bottom: 10px;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        margin: 10px;
        padding: 15px;
    }

    .login-container {
        margin: 20px;
        padding: 20px;
    }

    nav ul {
        flex-direction: row;
        flex-wrap: wrap;
        justify-content: center;
        gap: 10px;
    }

    nav ul li a {
        padding: 5px 8px;
        font-size: 14px;
    }

    .question-container {
        padding: 15px;
    }

    .option {
        padding: 8px;
    }
}

/* 只有在宽度小于300px时才使用垂直导航 */
@media (max-width: 300px) {
    nav ul {
        flex-direction: column;
        align-items: center;
        gap: 5px;
    }

    nav ul li a {
        padding: 3px 6px;
        font-size: 12px;
    }
}

/* 加载动画 */
.loading {
    display: inline-block;
    width: 50px;
    height: 50px;
    border: 3px solid rgba(0, 0, 0, 0.1);
    border-radius: 50%;
    border-top-color: #4CAF50;
    animation: spin 1s ease-in-out infinite;
    margin: 20px auto;
    display: block;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* 页脚样式 */
footer {
    background-color: #333;
    color: white;
    text-align: center;
    padding: 15px;
    border-radius: 0 0 8px 8px;
    margin: 20px -20px -20px -20px;
    font-size: 14px;
}

footer p {
    margin: 0;
}