/**
 * Apple Compare - 公共样式文件
 * 包含所有页面共用的基础样式
 */

:root {
    /* 颜色变量 */
    --primary-color: #0071e3;
    --secondary-color: #06c;
    --text-color: #1d1d1f;
    --text-secondary: #86868b;
    --background-color: #f5f5f7;
    --card-background: #ffffff;
    --border-color: #d2d2d7;
    --hover-color: #0077ed;
    --highlight-bg: #fdf6e4;
    --highlight-border: #f7cf7c;
    --diff-color: #0071e3;
    --success-color: #34c759;
    --warning-color: #ff9500;
    
    /* 阴影变量 */
    --shadow-sm: 0 4px 12px rgba(0,0,0,0.08);
    --shadow-md: 0 8px 20px rgba(0,0,0,0.12);
    --shadow-lg: 0 12px 30px rgba(0,0,0,0.15);
    
    /* 圆角变量 */
    --border-radius-sm: 8px;
    --border-radius-md: 12px;
    --border-radius-lg: 18px;
    --border-radius-pill: 24px;
    
    /* 过渡变量 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* 重置样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

body {
    padding: 0;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

html {
    scroll-behavior: smooth;
}

/* 容器 */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px 60px;
}

/* 导航和头部 */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 40px;
}

.logo {
    font-size: 24px;
    font-weight: bold;
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-color);
    transition: color var(--transition-fast);
}

.logo:hover {
    color: var(--primary-color);
}

.nav {
    display: flex;
    gap: 20px;
    align-items: center;
}

.nav a {
    text-decoration: none;
    color: var(--text-color);
    padding: 8px 16px;
    border-radius: var(--border-radius-pill);
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    gap: 6px;
}

.nav a:hover, .nav a.active {
    background-color: rgba(0,0,0,0.05);
    color: var(--primary-color);
}

/* 语言切换器 */
.language-switcher {
    display: flex;
    align-items: center;
    margin-left: 10px;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-pill);
    padding: 2px;
    background-color: var(--card-background);
}

.language-btn {
    background: none;
    border: none;
    padding: 6px 12px;
    cursor: pointer;
    border-radius: 20px;
    font-size: 14px;
    color: var(--text-secondary);
    transition: all var(--transition-fast);
}

.language-btn.active {
    background-color: var(--primary-color);
    color: white;
}

/* 页脚 */
footer {
    padding: 40px 0;
    border-top: 1px solid var(--border-color);
    margin-top: 60px;
}

.footer-links {
    display: flex;
    flex-wrap: wrap;
    gap: 40px;
    margin-bottom: 30px;
}

.footer-section {
    flex: 1;
    min-width: 200px;
}

.footer-section h4 {
    font-size: 16px;
    margin-bottom: 15px;
    color: var(--text-color);
}

.footer-section a {
    display: block;
    color: var(--text-secondary);
    text-decoration: none;
    margin-bottom: 10px;
    font-size: 14px;
    transition: color var(--transition-fast);
}

.footer-section a:hover {
    color: var(--primary-color);
    text-decoration: underline;
}

.copyright {
    font-size: 13px;
    color: var(--text-secondary);
    line-height: 1.6;
    text-align: center;
}

/* 返回顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background-color: var(--primary-color);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    z-index: 99;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background-color: var(--hover-color);
    transform: translateY(-3px);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: 0 15px 40px;
    }
    
    header {
        flex-direction: column;
        align-items: flex-start;
        gap: 15px;
    }
    
    .nav {
        width: 100%;
        overflow-x: auto;
        padding-bottom: 5px;
    }
    
    .footer-links {
        flex-direction: column;
        gap: 30px;
    }
}

@media (max-width: 480px) {
    .nav a {
        padding: 6px 12px;
        font-size: 14px;
    }
    
    .back-to-top {
        width: 40px;
        height: 40px;
        bottom: 20px;
        right: 20px;
    }
}