/* 基础样式重置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', 'Microsoft YaHei', sans-serif;
}

:root {
    --primary: #4a6de5;
    --primary-light: #e8edff;
    --secondary: #f8f9fa;
    --text: #333;
    --text-light: #666;
    --border: #e1e5eb;
    --shadow: 0 8px 30px rgba(0, 0, 0, 0.08);
    --radius: 12px;
    --transition: all 0.3s ease;
}

body {
    background-color: #f5f7ff;
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

/* 页头样式 */
header {
    background: linear-gradient(135deg, var(--primary), #6a8eff);
    color: white;
    padding: 30px 40px;
    display: flex;
    align-items: center;
    gap: 20px;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 15px;
}

.logo-icon {
    display: flex;
    align-items: center;
    justify-content: center;
}

.logo-icon img {
    filter: brightness(0) invert(1); /* 使图标变为白色 */
}

.logo-text h1 {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 5px;
    text-align: center;
}

.logo-text p {
    opacity: 0.9;
    font-size: 0.95rem;
    text-align: center;
}

/* 加载状态 */
.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    color: var(--text-light);
}

.loading-spinner {
    width: 20px;
    height: 20px;
    border: 3px solid var(--primary-light);
    border-top: 3px solid var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* 主体布局 */
.main-content {
    display: flex;
    min-height: 600px;
}

/* 左侧导航 */
.sidebar {
    width: 280px;
    background: var(--secondary);
    border-right: 1px solid var(--border);
    padding: 25px 0;
    flex-shrink: 0;
}

.nav-header {
    padding: 0 25px 20px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 20px;
}

.nav-header h2 {
    font-size: 1.3rem;
    color: var(--text);
    display: flex;
    align-items: center;
    gap: 10px;
}

.category-list {
    list-style: none;
}

.category-item {
    padding: 18px 25px;
    border-left: 4px solid transparent;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.category-item:hover {
    background: var(--primary-light);
    border-left-color: var(--primary);
}

.category-item.active {
    background: var(--primary-light);
    border-left-color: var(--primary);
    color: var(--primary);
    font-weight: 600;
}

.category-item img {
    width: 20px;
    height: 20px;
    margin-right: 15px;
}

.category-name {
    flex-grow: 1;
}

.item-count {
    font-size: 1rem;
    padding: 2px 8px;
    border-radius: 10px;
    min-width: 24px;
    text-align: center;
}

/* 右侧内容区 */
.content-area {
    flex-grow: 1;
    padding: 30px;
}

.page-title {
    font-size: 1.8rem;
    margin-bottom: 25px;
    color: var(--text);
    display: flex;
    align-items: center;
    gap: 10px;
}

.back-button {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--primary-light);
    color: var(--primary);
    border: none;
    padding: 10px 18px;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    margin-bottom: 25px;
}

.back-button:hover {
    background: var(--primary);
    color: white;
    transform: translateX(-3px);
}

/* 二级问题列表 */
.question-list {
    display: grid;
    gap: 15px;
}

.question-item {
    background: white;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 22px 25px;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.question-item:hover {
    border-color: var(--primary);
    box-shadow: 0 5px 15px rgba(74, 109, 229, 0.1);
    transform: translateY(-2px);
}

.question-text {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text);
}

.question-arrow {
    color: var(--text-light);
    font-size: 1.2rem;
    transition: var(--transition);
}

.question-item:hover .question-arrow {
    color: var(--primary);
    transform: translateX(5px);
}

/* 三级答案页面 */
.answer-card {
    background: white;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    overflow: hidden;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.05);
}

.answer-header {
    background: var(--primary-light);
    padding: 25px 30px;
    border-bottom: 1px solid var(--border);
}

.answer-header h3 {
    font-size: 1.5rem;
    color: var(--text);
    line-height: 1.4;
}

.answer-body {
    padding: 30px;
    font-size: 1.05rem;
    line-height: 1.8;
}

.answer-body p {
    margin-bottom: 20px;
}

.answer-body ul, .answer-body ol {
    margin-left: 25px;
    margin-bottom: 20px;
}

.answer-body li {
    margin-bottom: 10px;
}

.tip-box {
    background: #f0f7ff;
    border-left: 4px solid var(--primary);
    padding: 18px 20px;
    margin: 25px 0;
    border-radius: 0 8px 8px 0;
}

.tip-box strong {
    color: var(--primary);
}

/* 首页欢迎内容 */
.welcome-content {
    text-align: center;
    padding: 60px 40px;
    max-width: 700px;
    margin: 0 auto;
}

.welcome-icon img {
    margin-bottom: 5px;
    color: var(--primary);
}

.welcome-content h2 {
    font-size: 2.2rem;
    margin-bottom: 20px;
    color: var(--text);
}

.welcome-content p {
    font-size: 1.1rem;
    color: var(--text-light);
    margin-bottom: 35px;
    line-height: 1.8;
}

.stats {
    display: flex;
    justify-content: center;
    gap: 40px;
    flex-wrap: wrap;
    margin-top: 40px;
}

.stat-item {
    text-align: center;
}

.stat-number {
    font-size: 2.2rem;
    font-weight: 700;
    color: var(--primary);
    display: block;
}

.stat-label {
    font-size: 0.95rem;
    color: var(--text-light);
    margin-top: 5px;
}

.error-message {
    text-align: center;
    padding: 40px;
    color: #e74c3c;
}

.error-message h3 {
    margin-bottom: 15px;
}

/* 页脚 */
footer {
    background: var(--secondary);
    padding: 25px 40px;
    border-top: 1px solid var(--border);
    text-align: center;
    color: var(--text-light);
    font-size: 0.95rem;
}

footer a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
}

footer a:hover {
    text-decoration: underline;
}

/* 响应式设计 */
@media (max-width: 992px) {
    .main-content {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        border-right: none;
        border-bottom: 1px solid var(--border);
    }
    
    .category-list {
        display: flex;
        overflow-x: auto;
        padding-bottom: 10px;
    }
    
    .category-item {
        min-width: 200px;
        border-left: none;
        border-bottom: 4px solid transparent;
    }
    
    .category-item:hover, .category-item.active {
        border-left: none;
        border-bottom-color: var(--primary);
    }
}

@media (max-width: 768px) {
    header {
        padding: 25px 20px;
    }
    
    .content-area {
        padding: 25px 20px;
    }
    
    .welcome-content {
        padding: 40px 20px;
    }
    
    .welcome-content h2 {
        font-size: 1.8rem;
    }
    
    .stats {
        gap: 25px;
    }
}

@media (max-width: 480px) {
    .logo {
        flex-direction: column;
        text-align: center;
        gap: 10px;
    }
    
    .logo-text h1 {
        font-size: 1.5rem;
    }
    
    .page-title {
        font-size: 1.5rem;
    }
    
    .question-item {
        padding: 18px 20px;
    }
    
    .answer-body {
        padding: 25px 20px;
    }
}