/* 
   Style.css - 高端建筑/家居改造类企业官网
   设计风格：现代简约、专业权威、高对比度
*/

/* 1. CSS变量定义 */
:root {
    /* 颜色变量 */
    --color-primary: #000000;
    --color-secondary: #0F0F0F;
    --color-accent: #FFFFFF;
    --color-text-main: #000000;
    --color-text-muted: #666666;
    --color-bg-light: #FFFFFF;
    --color-bg-off: #F9F9F9;
    --color-border: #E5E5E5;
    
    /* 字体变量 */
    --font-family: 'Inter', 'Montserrat', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --font-weight-bold: 700;
    --font-weight-medium: 500;
    --font-weight-light: 300;

    /* 间距与布局变量 */
    --section-padding: 120px;
    --container-width: 1280px;
    --transition-base: all 0.4s cubic-bezier(0.25, 0.8, 0.25, 1);
}

/* 2. 全局样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    background-color: var(--color-bg-light);
    color: var(--color-text-main);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition-base);
}

ul {
    list-style: none;
}

img {
    max-width: 100%;
    display: block;
}

h1, h2, h3, h4 {
    font-weight: var(--font-weight-bold);
    line-height: 1.1;
    letter-spacing: -0.02em;
}

/* 3. 基础组件样式 */

/* 容器 */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 40px;
}

/* 按钮样式 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 16px 32px;
    font-size: 14px;
    font-weight: var(--font-weight-bold);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    transition: var(--transition-base);
    cursor: pointer;
    border: 1px solid transparent;
}

.btn-primary {
    background-color: var(--color-primary);
    color: var(--color-accent);
}

.btn-primary:hover {
    background-color: #333;
    transform: translateY(-2px);
}

.btn-outline {
    background-color: transparent;
    border-color: var(--color-accent);
    color: var(--color-accent);
}

.btn-outline:hover {
    background-color: var(--color-accent);
    color: var(--color-primary);
}

.btn-ghost {
    background-color: transparent;
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.btn-ghost:hover {
    background-color: var(--color-primary);
    color: var(--color-accent);
}

/* 4. 导航栏样式 (Header) */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    padding: 30px 0;
    transition: var(--transition-base);
}

.header.scrolled {
    background-color: rgba(255, 255, 255, 0.95);
    padding: 20px 0;
    box-shadow: 0 4px 20px rgba(0,0,0,0.05);
}

.header.scrolled .nav-link {
    color: var(--color-text-main);
}

.nav-wrapper {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 24px;
    font-weight: 900;
    letter-spacing: -1px;
}

.nav-list {
    display: flex;
    gap: 40px;
}

.nav-link {
    font-size: 14px;
    font-weight: var(--font-weight-medium);
    color: var(--color-accent); /* 默认首屏透明背景下为白色 */
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.nav-link:hover {
    opacity: 0.7;
}

/* 5. 首屏样式 (Hero) */
.hero {
    height: 100vh;
    background: linear-gradient(rgba(0,0,0,0.4), rgba(0,0,0,0.4)), url('hero-bg.jpg') center/cover no-repeat;
    display: flex;
    align-items: center;
    color: var(--color-accent);
}

.hero-content {
    max-width: 800px;
}

.label-caps {
    display: block;
    font-size: 12px;
    font-weight: var(--font-weight-bold);
    text-transform: uppercase;
    letter-spacing: 0.3em;
    margin-bottom: 24px;
    color: rgba(255,255,255,0.8);
}

.hero-title {
    font-size: clamp(48px, 8vw, 90px);
    margin-bottom: 40px;
}

.hero-btns {
    display: flex;
    gap: 20px;
}

.hero-stats {
    display: flex;
    gap: 60px;
    margin-top: 80px;
}

.stat-item .stat-num {
    display: block;
    font-size: 40px;
    font-weight: var(--font-weight-bold);
}

.stat-item .stat-label {
    font-size: 12px;
    text-transform: uppercase;
    color: rgba(255,255,255,0.6);
}

/* 6. 内容区块通用样式 */
.section {
    padding: var(--section-padding) 0;
}

.section-dark {
    background-color: var(--color-primary);
    color: var(--color-accent);
}

.section-off-white {
    background-color: var(--color-bg-off);
}

.section-header {
    margin-bottom: 80px;
}

.section-title {
    font-size: 48px;
    margin-top: 10px;
}

/* 7. 卡片与布局组件 */

/* 交错布局 Grid */
.split-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 80px;
    align-items: center;
}

/* 服务列表样式 */
.service-list {
    border-top: 1px solid var(--color-border);
}

.service-item {
    padding: 30px 0;
    border-bottom: 1px solid var(--color-border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: var(--transition-base);
}

.service-item:hover {
    padding-left: 20px;
}

.service-num {
    font-size: 14px;
    margin-right: 40px;
    color: var(--color-text-muted);
}

.service-name {
    font-size: 24px;
    font-weight: var(--font-weight-bold);
}

/* Before/After 滑动容器样式 */
.comparison-slider {
    position: relative;
    width: 100%;
    aspect-ratio: 16 / 9;
    overflow: hidden;
    background: #ccc;
}

/* 8. 表单样式 */
.contact-form {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

.form-group.full {
    grid-column: span 2;
}

.form-input {
    width: 100%;
    padding: 20px;
    background-color: #f0f0f0;
    border: none;
    font-family: inherit;
    outline: none;
    transition: var(--transition-base);
}

.form-input:focus {
    background-color: #e8e8e8;
}

/* 9. 页脚样式 (Footer) */
.footer {
    background-color: var(--color-secondary);
    color: var(--color-accent);
    padding: 100px 0 40px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 60px;
    margin-bottom: 80px;
}

.footer-logo {
    font-size: 28px;
    font-weight: 900;
    margin-bottom: 24px;
}

.footer-desc {
    color: #999;
    max-width: 300px;
}

.footer-title {
    font-size: 16px;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: 30px;
}

.footer-links li {
    margin-bottom: 15px;
}

.footer-links a {
    color: #999;
    font-size: 14px;
}

.footer-links a:hover {
    color: var(--color-accent);
}

.footer-bottom {
    padding-top: 40px;
    border-top: 1px solid #222;
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    color: #666;
}

/* 10. 实用工具类 */
.mb-10 { margin-bottom: 10px; }
.mb-20 { margin-bottom: 20px; }
.mb-40 { margin-bottom: 40px; }
.text-upper { text-transform: uppercase; }
.text-muted { color: var(--color-text-muted); }

/* 11. 响应式媒体查询 */

/* Tablet */
@media (max-width: 1024px) {
    :root {
        --section-padding: 80px;
    }
    
    .nav-list {
        display: none; /* 实际开发中应替换为汉堡菜单 */
    }
    
    .split-grid {
        gap: 40px;
    }
    
    .hero-title {
        font-size: 56px;
    }

    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }
}

/* Mobile */
@media (max-width: 768px) {
    .container {
        padding: 0 24px;
    }

    .split-grid {
        grid-template-columns: 1fr;
    }

    .hero-btns {
        flex-direction: column;
    }

    .hero-stats {
        flex-wrap: wrap;
        gap: 30px;
    }

    .section-title {
        font-size: 32px;
    }

    .contact-form {
        grid-template-columns: 1fr;
    }

    .form-group.full {
        grid-column: span 1;
    }

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .footer-bottom {
        flex-direction: column;
        gap: 20px;
        text-align: center;
    }
}

/* 12. 动画 */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.reveal {
    animation: fadeIn 0.8s ease forwards;
}