/* 全局样式 */
:root {
    --primary-color: #3498db;
    --success-color: #27ae60;
    --danger-color: #e74c3c;
    --light-gray: #f8f9fa;
    --medium-gray: #e9ecef;
    --dark-gray: #495057;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    --transition: all 0.3s ease;
}

* {
    box-sizing: border-box;
}

body {
    background-color: var(--light-gray);
    color: #333;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    padding-top: 20px;
    padding-bottom: 40px;
}

.container {
    max-width: 1140px;
    padding: 0 15px;
    margin: 0 auto;
}

/* 头部样式 */
.site-header {
    margin-bottom: 30px;
    padding: 20px 0;
    border-bottom: 1px solid var(--medium-gray);
}

.site-title {
    color: var(--primary-color);
    font-size: 2.5rem;
    margin-bottom: 10px;
    font-weight: 700;
}

.site-description {
    color: var(--dark-gray);
    font-size: 1.1rem;
    margin: 0;
}

/* 导航按钮 */
.nav-buttons {
    margin-bottom: 30px;
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
}

.btn-action {
    padding: 10px 20px;
    font-size: 1rem;
    font-weight: 500;
    border-radius: 4px;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.btn-action:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

/* 卡片样式 */
.card {
    background-color: #fff;
    border-radius: 8px;
    box-shadow: var(--shadow);
    margin-bottom: 30px;
    overflow: hidden;
    transition: var(--transition);
}

.card:hover {
    box-shadow: 0 6px 18px rgba(0, 0, 0, 0.12);
}

.card-header {
    background-color: var(--primary-color);
    color: #fff;
    padding: 15px 20px;
}

.card-title {
    margin: 0;
    font-size: 1.5rem;
    font-weight: 600;
}

.card-body {
    padding: 20px;
}

/* 题目列表样式 */
.section-title {
    color: var(--dark-gray);
    margin-bottom: 30px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--primary-color);
    display: inline-block;
}

.question-list {
    margin-bottom: 40px;
}

.question-card {
    height: 100%;
    display: flex;
    flex-direction: column;
}

.question-preview {
    display: flex;
    margin-bottom: 15px;
    gap: 15px;
}

.question-thumbnail {
    flex: 0 0 100px;
    height: 100px;
    overflow: hidden;
    border-radius: 4px;
}

.question-thumbnail img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
    cursor: pointer;
}

.question-thumbnail img:hover {
    transform: scale(1.05);
}

.question-content {
    flex: 1;
}

.question-text {
    margin: 0;
    color: var(--dark-gray);
    overflow: hidden;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
}

.question-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    font-size: 0.9rem;
    color: #6c757d;
    margin-bottom: 15px;
    padding-bottom: 10px;
    border-bottom: 1px dashed var(--medium-gray);
}

.question-stats {
    margin-bottom: 15px;
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.stats-badge {
    background-color: var(--light-gray);
    color: var(--dark-gray);
    padding: 3px 10px;
    border-radius: 20px;
    font-size: 0.85rem;
    display: inline-flex;
    align-items: center;
    gap: 5px;
}

.stats-badge.top {
    background-color: rgba(39, 174, 96, 0.1);
    color: var(--success-color);
    font-weight: 500;
}

.stats-badge.has-answer {
    background-color: rgba(39, 174, 96, 0.1);
    color: var(--success-color);
}

.btn-view-question {
    margin-top: auto;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

/* 表单样式 */
.form-container {
    max-width: 700px;
    margin: 0 auto 40px;
}

.form-group {
    margin-bottom: 25px;
}

.form-label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--dark-gray);
}

.required-mark {
    color: var(--danger-color);
}

.form-control {
    width: 100%;
    padding: 10px 15px;
    font-size: 1rem;
    border: 1px solid #ced4da;
    border-radius: 4px;
    transition: var(--transition);
}

.form-control:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.25);
    outline: none;
}

.help-text {
    margin-top: 5px;
    font-size: 0.9rem;
    color: #6c757d;
}

.btn-submit {
    padding: 12px 20px;
    font-size: 1rem;
    font-weight: 600;
}

/* 图片上传样式 */
.image-upload-container {
    margin-bottom: 10px;
}

.image-upload-label {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 30px;
    border: 2px dashed #ced4da;
    border-radius: 8px;
    background-color: var(--light-gray);
    color: var(--dark-gray);
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
    margin-bottom: 15px;
}

.image-upload-label:hover {
    border-color: var(--primary-color);
    background-color: rgba(52, 152, 219, 0.05);
}

.image-upload-label i {
    margin-bottom: 10px;
    color: var(--primary-color);
}

#question_image, #solve_image {
    display: none;
}

.img-preview {
    max-width: 100%;
    max-height: 300px;
    display: none;
    margin: 10px auto;
    border-radius: 4px;
    box-shadow: var(--shadow);
}

/* 题目详情页样式 */
.question-image-container {
    margin: 20px 0;
    text-align: center;
}

.question-image {
    max-width: 100%;
    max-height: 500px;
    border-radius: 4px;
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: var(--transition);
}

.question-image:hover {
    transform: scale(1.01);
}

.answer-item {
    padding: 15px;
    border-bottom: 1px solid var(--medium-gray);
    margin-bottom: 15px;
}

.answer-item:last-child {
    border-bottom: none;
}

.answer-time {
    color: #6c757d;
    font-size: 0.9rem;
    margin-bottom: 8px;
}

.answer-result {
    margin-bottom: 10px;
    font-size: 1.1rem;
}

.answer-text {
    margin: 10px 0;
    padding: 10px;
    background-color: var(--light-gray);
    border-radius: 4px;
}

.answer-image {
    max-width: 300px;
    max-height: 200px;
    margin-top: 10px;
    border-radius: 4px;
    cursor: pointer;
}

/* 分页样式 */
.pagination {
    display: flex;
    justify-content: center;
    margin: 30px 0;
    padding-left: 0;
    list-style: none;
}

.pagination li {
    margin: 0 3px;
}

.pagination a {
    display: inline-block;
    padding: 8px 15px;
    background-color: #fff;
    border: 1px solid #dee2e6;
    border-radius: 4px;
    color: var(--primary-color);
    text-decoration: none;
    transition: var(--transition);
}

.pagination a:hover {
    background-color: var(--light-gray);
    border-color: var(--primary-color);
}

.pagination .active a {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
    color: #fff;
}

.pagination .disabled a {
    color: #6c757d;
    pointer-events: none;
    background-color: #fff;
    border-color: #dee2e6;
}

/* 模态框图片样式 */
.modal-image {
    display: block;
    margin: 0 auto;
    max-width: 100%;
    max-height: 80vh;
}

/* 页脚样式 */
.site-footer {
    text-align: center;
    padding: 20px 0;
    margin-top: 50px;
    color: #6c757d;
    font-size: 0.9rem;
    border-top: 1px solid var(--medium-gray);
}

/* 返回链接 */
.back-link {
    margin-bottom: 20px;
    display: inline-flex;
    align-items: center;
    gap: 5px;
}

/* 页面标题 */
.page-header {
    margin-bottom: 30px;
}

.page-header h1 {
    color: var(--primary-color);
}

/* 响应式样式 */
@media (max-width: 768px) {
    .site-title {
        font-size: 2rem;
    }
    
    .question-preview {
        flex-direction: column;
    }
    
    .question-thumbnail {
        width: 100%;
        flex: none;
    }
    
    .col-md-6 {
        width: 100%;
        padding: 0 15px 20px;
    }
    
    .nav-buttons {
        flex-direction: column;
    }
    
    .btn-action {
        width: 100%;
    }
}