/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent; /* 移除移动端点击高亮 */
}

:root {
    /* Plume.org 风格配色 */
    --bg-main: #F7F7F5;
    --bg-card: #FFFFFF;
    --text-main: #132A13;
    --text-light: #4A5D4A;
    --accent: #C4F382;
    --accent-hover: #B0E070;
    --border: rgba(19, 42, 19, 0.08);
    
    /* 尺寸变量 */
    --radius-btn: 999px;
    --radius-card: 32px;
    --radius-card-mobile: 24px;
    
    /* 响应式间距 */
    --section-gap: clamp(4rem, 10vw, 8rem);
    --container-padding: clamp(1.25rem, 4vw, 2rem);
    
    --transition: all 0.4s cubic-bezier(0.25, 1, 0.5, 1);
}

html {
    scroll-behavior: smooth;
    font-size: 16px; /* 基准字体 */
}

body {
    font-family: 'Space Grotesk', 'Noto Sans SC', -apple-system, sans-serif;
    background-color: var(--bg-main);
    color: var(--text-main);
    line-height: 1.5;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

/* Container - 统一边距 */
.container {
    max-width: 1300px;
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* =========================================
   Navigation - 响应式导航栏
   ========================================= */
nav {
    position: fixed;
    top: 1rem;
    left: 50%;
    transform: translateX(-50%);
    width: calc(100% - 2rem); /* 移动端留出边距 */
    max-width: 1300px;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(255,255,255,0.5);
    border-radius: var(--radius-btn);
    padding: 0.6rem 1.5rem;
    transition: var(--transition);
}

nav.scrolled {
    background: rgba(255, 255, 255, 0.95);
    box-shadow: 0 4px 20px rgba(0,0,0,0.03);
}

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

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-main);
    text-decoration: none;
    letter-spacing: -0.02em;
    z-index: 1002; /* 确保在移动菜单之上 */
}

/* PC 端菜单 */
.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
    align-items: center;
    margin: 0;
    padding: 0;
}

.nav-links a {
    color: var(--text-main);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    transition: opacity 0.3s;
}

.nav-links a:hover {
    opacity: 0.6;
}

/* 右侧功能区 (语言+汉堡菜单) */
.right-nav-group {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    z-index: 1002;
}

.lang-switch {
    display: flex;
    background: #EBEBE8;
    padding: 3px;
    border-radius: var(--radius-btn);
}

.lang-btn {
    padding: 5px 12px;
    border: none;
    background: transparent;
    color: var(--text-light);
    cursor: pointer;
    border-radius: var(--radius-btn);
    font-weight: 600;
    font-size: 0.8rem;
    transition: var(--transition);
}

.lang-btn.active {
    background: #FFF;
    color: var(--text-main);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

/* 移动端汉堡菜单图标 */
.mobile-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    cursor: pointer;
    width: 32px;
    height: 32px;
    z-index: 1002;
}

.mobile-toggle span {
    width: 20px;
    height: 2px;
    background: var(--text-main);
    border-radius: 2px;
    transition: 0.3s ease-in-out;
    margin: 0 auto; /* 居中 */
}

/* =========================================
   Hero Section - 流体排版
   ========================================= */
.hero {
    min-height: 100vh; /* PC端全屏 */
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 8rem 1rem 4rem; /* 顶部留出导航栏空间 */
    position: relative;
}

.hero-content {
    width: 100%;
    max-width: 1000px;
    z-index: 1;
}

/* 核心：使用 clamp 实现标题字号在 3rem 到 6rem 之间平滑过渡 */
.hero h1 {
    font-size: clamp(3rem, 9vw, 5.5rem); 
    font-weight: 700;
    line-height: 1.05;
    letter-spacing: -0.03em;
    margin-bottom: 1.5rem;
    color: var(--text-main);
}

.hero h2 {
    font-size: clamp(0.9rem, 3vw, 1.2rem);
    font-weight: 600;
    color: var(--text-light);
    margin-bottom: 2rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
}

.hero-tagline {
    font-size: clamp(1.1rem, 4vw, 1.5rem);
    color: var(--text-main);
    margin-bottom: 3rem;
    font-weight: 400;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    line-height: 1.5;
}

/* 按钮样式 */
.cta-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 1.2rem 3rem;
    background: var(--accent);
    color: var(--text-main);
    text-decoration: none;
    border-radius: var(--radius-btn);
    font-weight: 600;
    font-size: 1.05rem;
    transition: var(--transition);
    width: fit-content; /* 移动端自适应宽度 */
}

.cta-btn:active {
    transform: scale(0.96);
}

/* =========================================
   Sections & Grid - 布局系统
   ========================================= */
.section {
    padding: var(--section-gap) 0;
}

.section-header {
    margin-bottom: clamp(3rem, 8vw, 5rem);
    display: flex;
    flex-direction: column; /* 移动端默认垂直 */
    gap: 1rem;
    border-bottom: 1px solid var(--border);
    padding-bottom: 2rem;
}

/* PC端 Header 布局 */
@media (min-width: 768px) {
    .section-header {
        flex-direction: row;
        justify-content: space-between;
        align-items: flex-end;
    }
}

.section-title {
    font-size: clamp(2.5rem, 6vw, 3.5rem);
    font-weight: 600;
    letter-spacing: -0.02em;
    line-height: 1;
    color: var(--text-main);
}

.section-subtitle {
    font-size: 0.85rem;
    color: var(--text-light);
    text-transform: uppercase;
    letter-spacing: 0.15em;
    font-weight: 700;
    margin-bottom: 0.5rem;
    display: block;
}

/* Grid System */
.grid {
    display: grid;
    gap: 20px;
    width: 100%;
}

/* 移动端优先：默认 1 列 */
.grid-4, .grid-2 {
    grid-template-columns: 1fr; 
}

/* 平板断点：2 列 */
@media (min-width: 640px) {
    .grid-4, .grid-2 {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* PC断点：4 列 */
@media (min-width: 1024px) {
    .grid-4 {
        grid-template-columns: repeat(4, 1fr);
    }
}

/* Cards */
.card {
    background: var(--bg-card);
    border-radius: var(--radius-card);
    padding: clamp(2rem, 5vw, 3rem); /* 响应式内边距 */
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    height: 100%; /* 确保高度一致 */
}

.card:hover {
    transform: translateY(-6px);
    box-shadow: 0 12px 30px rgba(0,0,0,0.06);
}

/* About Card Special */
.about-card {
    background: #fff;
    padding: clamp(2rem, 6vw, 4rem);
}

.about-card p {
    font-size: clamp(1.2rem, 3vw, 1.8rem); /* 移动端字体不宜过大 */
    line-height: 1.5;
    font-weight: 400;
}

/* Mission Quote */
.mission-quote {
    background: var(--text-main);
    color: var(--accent);
    padding: clamp(3rem, 8vw, 6rem) 2rem;
    border-radius: var(--radius-card);
    text-align: center;
    margin: 2rem 0;
}

.mission-quote blockquote {
    font-size: clamp(1.8rem, 5vw, 3.5rem);
    font-weight: 500;
    line-height: 1.2;
    margin-bottom: 2rem;
}

.mission-text {
    font-size: clamp(1rem, 2vw, 1.2rem);
    color: rgba(255, 255, 255, 0.8);
    max-width: 700px;
    margin: 0 auto;
}

/* Service Icons & Numbers */
.service-number {
    font-size: clamp(2.5rem, 4vw, 4rem);
    font-weight: 600;
    color: #E0E0E0;
    margin-bottom: 1rem;
}

.advantage-icon {
    width: 64px;
    height: 64px;
    font-size: 2rem;
    background: var(--bg-main);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
}

/* Contact Section */
.contact-section {
    background: var(--accent);
    border-radius: var(--radius-card);
    padding: clamp(3rem, 8vw, 6rem) 1.5rem; /* 移动端减少 Padding */
    text-align: center;
    margin-bottom: 4rem;
}

.contact-title {
    font-size: clamp(2.5rem, 8vw, 4.5rem);
    line-height: 1;
    margin-bottom: 1.5rem;
    color: var(--text-main);
}

.contact-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-top: 2rem;
}

.contact-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.6rem;
    padding: 1rem 2rem;
    min-width: 140px;
    background: var(--text-main);
    color: #fff;
    border-radius: var(--radius-btn);
    text-decoration: none;
    font-weight: 600;
    transition: transform 0.2s;
}

.contact-btn:hover {
    transform: scale(1.05);
}

/* Footer */
footer {
    padding: 3rem 0;
    text-align: center;
    border-top: 1px solid var(--border);
    color: var(--text-light);
}

/* =========================================
   Mobile Specific Overrides (Media Queries)
   ========================================= */

@media (max-width: 768px) {
    /* 1. 导航栏变为全屏菜单 */
    nav {
        width: calc(100% - 1.5rem);
        padding: 0.8rem 1rem;
        top: 0.8rem;
    }

    .mobile-toggle {
        display: flex; /* 显示汉堡按钮 */
    }

    .nav-links {
        position: fixed;
        top: 0;
        left: 0;
        width: 100vw;
        height: 100vh;
        background: var(--bg-main);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 2rem;
        z-index: 1001; /* 在汉堡按钮下方，但覆盖页面 */
        padding: 2rem;
        
        /* 动画状态：默认隐藏 */
        opacity: 0;
        visibility: hidden;
        transform: translateY(-20px);
        transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    }

    .nav-links.active {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
    }

    .nav-links a {
        font-size: 1.5rem; /* 移动端菜单字体变大 */
        font-weight: 600;
    }
    
    /* 2. 卡片圆角在手机上稍微小一点 */
    .card, .mission-quote, .contact-section {
        border-radius: var(--radius-card-mobile);
    }

    /* 3. Hero 高度自适应，避免手机浏览器地址栏遮挡 */
    .hero {
        min-height: 90vh;
        padding-top: 7rem;
    }
    
    /* 4. 按钮全宽处理 (可选) */
    .cta-btn {
        width: 100%;
    }
    .contact-btn {
        width: 100%;
        max-width: 300px;
    }
}