/* ==========================================================================
   1. CSS RESET & VARIABLES (初始化与全局变量)
   ========================================================================== */
:root {
    /* 蔬菜白菜品牌色系 */
    --primary-color: #2d6a4f;       /* 深白菜绿：用于主标题、核心导航、主要CTA */
    --secondary-color: #52b788;     /* 鲜嫩菜心绿：用于高亮、Hover状态、辅助元素 */
    --accent-color: #74c69d;        /* 嫩芽绿：用于微弱过渡与边框 */
    --bg-color: #f4f9f4;            /* 生态白/淡绿：极淡雅的底色，降低视网膜疲劳 */
    --bg-light: #ffffff;            /* 纯白：用于卡片与区块交替衬托 */
    --text-color: #1c2519;          /* 深炭黑：高对比度，确保极致的文字易读性 */
    --text-muted: #4f5e4b;          /* 灰绿炭黑：用于次要描述文字 */
    
    /* 字阶排版系统 (Typography) */
    --font-sans: 'Helvetica Neue', Arial, 'Noto Sans CJK SC', 'PingFang SC', sans-serif;
    --font-size-base: 16px;
    
    /* 布局与留白规范 */
    --container-width: 1200px;
    --section-padding: 90px 0;      /* 严守大留白，赋予网页尊贵的“呼吸感” */
    
    /* 动效与过渡 */
    --transition-smooth: cubic-bezier(0.25, 0.8, 0.25, 1);
    --transition-duration: 0.3s;
    --shadow-sm: 0 2px 8px rgba(45, 106, 79, 0.05);
    --shadow-md: 0 10px 30px rgba(45, 106, 79, 0.08);
    --shadow-lg: 0 15px 40px rgba(45, 106, 79, 0.12);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    color: var(--text-color);
    background-color: var(--bg-color);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    scroll-behavior: smooth; /* 纯CSS实现多区块锚点平滑滚动 */
}

body {
    overflow-x: hidden;
}

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

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

input, button, textarea {
    font-family: inherit;
    font-size: inherit;
    outline: none;
}

/* ==========================================================================
   2. TYPOGRAPHY & LAYOUT (字阶与公用布局)
   ========================================================================== */
.container {
    width: 100%;
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 24px;
}

section {
    padding: var(--section-padding);
    position: relative;
}

/* 区块交替背景色，营造清晰的视觉层次 */
section:nth-child(even) {
    background-color: var(--bg-light);
}

h1, h2, h3, h4 {
    font-weight: 700;
    line-height: 1.3;
    color: var(--primary-color);
}

h2 {
    font-size: 2.25rem; /* 36px */
    text-align: center;
    margin-bottom: 16px;
    position: relative;
}

/* 优雅的装饰短线 - 强化行业属性 */
h2::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    margin: 12px auto 0;
    border-radius: 2px;
}

.section-subtitle {
    font-size: 1.125rem; /* 18px */
    color: var(--text-muted);
    text-align: center;
    max-width: 700px;
    margin: 0 auto 60px;
}

/* ==========================================================================
   3. BUTTONS & INTERACTION (按钮动态回馈规范)
   ========================================================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 32px;
    font-weight: 600;
    border-radius: 8px;
    border: 2px solid transparent;
    cursor: pointer;
    transition: all var(--transition-duration) var(--transition-smooth);
    box-shadow: var(--shadow-sm);
}

/* 主 CTA 按钮 - 充满生命力的深绿 */
.btn-primary {
    background-color: var(--primary-color);
    color: var(--bg-light);
}

.btn-primary:hover {
    background-color: var(--secondary-color);
    transform: translateY(-3px) scale(1.03); /* 轻微放大与上浮 */
    box-shadow: 0 8px 20px rgba(82, 183, 136, 0.4); /* 微弱发光效果 */
}

.btn-primary:active {
    transform: translateY(-1px) scale(1);
}

/* 辅助 CTA 按钮 - 边框镂空 */
.btn-secondary {
    background-color: transparent;
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.btn-secondary:hover {
    background-color: rgba(45, 106, 79, 0.05);
    border-color: var(--secondary-color);
    color: var(--secondary-color);
    transform: translateY(-3px);
}

/* ==========================================================================
   4. HEADER & NAVIGATION (吸顶导览列与汉堡菜单)
   ========================================================================== */
.site-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px); /* 现代毛玻璃效果 */
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-duration) var(--transition-smooth);
}

.header-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 80px;
}

/* 纯文字 Logo 样式设计 - 绝无图片 */
.logo-text {
    font-size: 1.35rem;
    font-weight: 800;
    letter-spacing: 0.5px;
    color: var(--primary-color);
    display: flex;
    align-items: center;
}

.logo-text span {
    color: var(--secondary-color);
    margin-left: 2px;
}

/* 导航选单 */
.nav-menu {
    display: flex;
    align-items: center;
    list-style: none;
    gap: 32px;
}

.nav-link {
    font-weight: 500;
    color: var(--text-color);
    position: relative;
    padding: 8px 0;
}

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

/* 优雅的下划线 Hover 动画 */
.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--secondary-color);
    transition: width var(--transition-duration) var(--transition-smooth);
}

.nav-link:hover::after {
    width: 100%;
}

.header-cta .btn {
    padding: 8px 20px;
    font-size: 0.95rem;
}

/* 移动端汉堡菜单触发器 */
.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: space-between;
    width: 30px;
    height: 21px;
    background: transparent;
    border: none;
    cursor: pointer;
    z-index: 1100;
}

.nav-toggle span {
    width: 100%;
    height: 3px;
    background-color: var(--primary-color);
    border-radius: 2px;
    transition: all var(--transition-duration) var(--transition-smooth);
}

/* ==========================================================================
   5. HERO SECTION (英雄区)
   ========================================================================== */
.hero-section {
    padding-top: 180px; /* 留出吸顶导航的空间 */
    padding-bottom: 120px;
    background: linear-gradient(135deg, rgba(244,249,244,0.9) 0%, rgba(255,255,255,0.7) 100%), 
                url('/images/hero-bg.jpg') no-repeat center center / cover;
    display: flex;
    align-items: center;
    min-height: calc(100vh - 80px);
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.hero-content h1 {
    font-size: 3.5rem; /* 56px 大气磅礴 */
    line-height: 1.2;
    margin-bottom: 24px;
    letter-spacing: -0.5px;
}

.hero-description {
    font-size: 1.35rem; /* 21.6px */
    color: var(--text-muted);
    margin-bottom: 40px;
    line-height: 1.6;
}

.hero-actions {
    display: flex;
    justify-content: center;
    gap: 20px;
}

/* ==========================================================================
   6. RESPONSIVE MEDIA QUERIES (响应式媒体查询 - 移动端优先)
   ========================================================================== */
@media (max-width: 992px) {
    :root {
        --section-padding: 70px 0;
    }
    
    .hero-content h1 {
        font-size: 2.75rem;
    }
    
    /* 汉堡菜单激活状态的样式预留 */
    .nav-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 280px;
        height: 100vh;
        background-color: var(--bg-light);
        box-shadow: var(--shadow-lg);
        flex-direction: column;
        align-items: flex-start;
        justify-content: flex-start;
        padding: 100px 40px 40px;
        gap: 24px;
        transition: right var(--transition-duration) var(--transition-smooth);
    }
    
    /* 当 JS 为 body 或 nav 加上 .nav-open 类时的表现 */
    .nav-open .nav-menu {
        right: 0;
    }
    
    .nav-open .nav-toggle span:nth-child(1) {
        transform: translateY(9px) rotate(45deg);
    }
    
    .nav-open .nav-toggle span:nth-child(2) {
        opacity: 0;
    }
    
    .nav-open .nav-toggle span:nth-child(3) {
        transform: translateY(-9px) rotate(-45deg);
    }
    
    .header-cta {
        display: none; /* 移动端收纳或隐藏次要CTA */
    }
}

@media (max-width: 576px) {
    .hero-content h1 {
        font-size: 2.1rem;
    }
    
    .hero-description {
        font-size: 1.1rem;
    }
    
    .hero-actions {
        flex-direction: column;
        gap: 12px;
        padding: 0 20px;
    }
    
    h2 {
        font-size: 1.75rem;
    }
    
    .btn {
        width: 100%;
    }
}