/* ==========================================================================
   mansion88·明升叉车集团股份有限公司 - 核心样式表
   Role: Senior Frontend Architect & UI/UX Director
   Design System: Industrial Heavy-Duty Modern (AAA Contrast Ratio)
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. 基础重设与核心变量 (Variables & Reset)
   -------------------------------------------------------------------------- */
:root {
    /* 品牌色彩体系 */
    --color-primary: #F39C12;       /* 明升重工橙 */
    --color-primary-hover: #E67E22; /* 深橙（悬停色） */
    --color-dark-bg: #1A1A1A;      /* 工业深黑主背景 */
    --color-dark-surface: #262626; /* 次要卡片背景 */
    --color-dark-card: #333333;    /* 三级元素背景 */
    --color-text-light: #FFFFFF;   /* 纯白文字 */
    --color-text-muted: #B3B3B3;   /* 灰度文本（确保高对比度） */
    --color-success: #2ECC71;      /* 成功状态色 */
    
    /* 留白与间距规范 */
    --section-padding: 100px 0;
    --container-max-width: 1200px;
    
    /* 字体系统 */
    --font-sans: 'Helvetica Neue', Arial, 'Noto Sans CJK SC', 'Microsoft YaHei', sans-serif;
    
    /* 微交互动画过渡 */
    --transition-smooth: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-sans);
    background-color: var(--color-dark-bg);
    color: var(--color-text-light);
    line-height: 1.6;
    overflow-x: hidden;
}

/* --------------------------------------------------------------------------
   2. 通用原子组件与网格系统 (Layout & Components)
   -------------------------------------------------------------------------- */
.container {
    width: 100%;
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 24px;
}

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

.section:nth-child(even) {
    background-color: var(--color-dark-surface);
}

/* 视觉层级标题 */
.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    letter-spacing: 1px;
    color: var(--color-text-light);
    margin-bottom: 15px;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background-color: var(--color-primary);
    margin: 12px auto 0 auto;
    border-radius: 2px;
}

.section-subtitle {
    font-size: 1.1rem;
    color: var(--color-text-muted);
    max-width: 600px;
    margin: 0 auto;
}

/* 高性能工业风按钮 (CTA) */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 32px;
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    border-radius: 4px;
    transition: var(--transition-smooth);
    cursor: pointer;
    border: none;
    outline: none;
}

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

.btn-primary:hover, .btn-primary:focus {
    background-color: var(--color-primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(243, 156, 18, 0.3);
}

.btn-outline {
    background-color: transparent;
    color: var(--color-text-light);
    border: 2px solid var(--color-text-light);
}

.btn-outline:hover, .btn-outline:focus {
    background-color: var(--color-text-light);
    color: var(--color-dark-bg);
    transform: translateY(-2px);
}

/* --------------------------------------------------------------------------
   3. 吸顶式导览列 (Header & Navigation)
   -------------------------------------------------------------------------- */
.header-nav {
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: rgba(26, 26, 26, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    height: 80px;
    display: flex;
    align-items: center;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

/* 纯 HTML/CSS 打造的品牌文字 Logo */
.logo-brand {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--color-text-light);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
}

.logo-brand span {
    color: var(--color-primary);
    background: rgba(243, 156, 18, 0.1);
    padding: 2px 8px;
    border-radius: 4px;
    border: 1px solid rgba(243, 156, 18, 0.3);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 32px;
    align-items: center;
}

.nav-link {
    color: var(--color-text-muted);
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    transition: var(--transition-smooth);
    padding: 8px 0;
    position: relative;
}

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-primary);
    transition: var(--transition-smooth);
}

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

/* 汉堡菜单按钮（移动端专属） */
.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 6px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
    z-index: 1001;
}

.menu-toggle span {
    display: block;
    width: 28px;
    height: 3px;
    background-color: var(--color-text-light);
    transition: var(--transition-smooth);
    border-radius: 2px;
}

/* --------------------------------------------------------------------------
   4. 各核心区块具体样式 (Section Layouts)
   -------------------------------------------------------------------------- */

/* 区块 2：英雄视觉区 (Hero Section) */
.hero-section {
    min-height: calc(100vh - 80px);
    display: flex;
    align-items: center;
    background: linear-gradient(rgba(26, 26, 26, 0.6), rgba(26, 26, 26, 0.9)), 
                url('/images/hero-bg.jpg') no-repeat center center / cover;
    position: relative;
}

.hero-content {
    max-width: 700px;
}

.hero-tagline {
    font-size: 1.1rem;
    color: var(--color-primary);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 2px;
    margin-bottom: 20px;
}

.hero-title {
    font-size: 3.5rem;
    line-height: 1.2;
    font-weight: 800;
    margin-bottom: 24px;
    text-shadow: 0 4px 10px rgba(0,0,0,0.5);
}

.hero-description {
    font-size: 1.2rem;
    color: var(--color-text-muted);
    margin-bottom: 40px;
}

.hero-cta-group {
    display: flex;
    gap: 16px;
}

/* 区块 3：行业痛点区 (Pain Points Section) */
.pain-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.pain-card {
    background-color: var(--color-dark-surface);
    padding: 40px 30px;
    border-radius: 8px;
    border-top: 4px solid #E74C3C; /* 警示红暗指痛点 */
    transition: var(--transition-smooth);
}

.pain-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 30px rgba(0,0,0,0.3);
}

.pain-icon-wrapper {
    margin-bottom: 20px;
    color: #E74C3C;
}

.pain-card h3 {
    font-size: 1.3rem;
    margin-bottom: 15px;
    color: var(--color-text-light);
}

.pain-card p {
    color: var(--color-text-muted);
    font-size: 0.95rem;
}

/* 区块 4：解决方案区 (Solutions Section) */
.solutions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
    gap: 40px;
}

.solution-card {
    background-color: var(--color-dark-card);
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.05);
    transition: var(--transition-smooth);
}

.solution-card:hover {
    transform: translateY(-5px);
    border-color: var(--color-primary);
    box-shadow: 0 15px 35px rgba(0,0,0,0.4);
}

.solution-img-box {
    position: relative;
    width: 100%;
    height: 240px;
    overflow: hidden;
    background-color: #000;
}

.solution-img-box img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition-smooth);
}

.solution-card:hover .solution-img-box img {
    transform: scale(1.08);
}

.solution-info {
    padding: 30px;
}

.solution-info h3 {
    font-size: 1.4rem;
    margin-bottom: 12px;
}

.solution-desc {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    margin-bottom: 20px;
}

.solution-specs {
    list-style: none;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 15px;
}

.solution-specs li {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    margin-bottom: 8px;
    display: flex;
    justify-content: space-between;
}

.solution-specs li span {
    color: var(--color-text-light);
    font-weight: 500;
}

/* 区块 5：E-E-A-T 信任背书区 (Social Proof Section) */
.trust-metrics {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
    text-align: center;
    margin-bottom: 60px;
}

.metric-item .number {
    font-size: 3rem;
    font-weight: 800;
    color: var(--color-primary);
    line-height: 1;
    margin-bottom: 10px;
}

.metric-item .label {
    font-size: 1rem;
    color: var(--color-text-muted);
}

.partner-logos {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 30px;
    opacity: 0.6;
    filter: grayscale(100%);
    transition: var(--transition-smooth);
    margin-top: 40px;
}

.partner-logos:hover {
    opacity: 0.9;
    filter: grayscale(0%);
}

.partner-logos img {
    height: 45px;
    object-fit: contain;
    mix-blend-mode: screen; /* 核心追加：自动过滤掉 JPG 里的黑色背景，只留下纯白 Logo 图章 */
}

/* 区块 6：关于明升 (About Us Section) */
.about-wrapper {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.about-text h3 {
    font-size: 1.8rem;
    margin-bottom: 20px;
    color: var(--color-primary);
}

.about-text p {
    color: var(--color-text-muted);
    margin-bottom: 20px;
    font-size: 1rem;
}

.about-features {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-top: 30px;
}

.about-feature-item {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 0.95rem;
    font-weight: 500;
}

.about-img-box {
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 20px 40px rgba(0,0,0,0.4);
}

.about-img-box img {
    width: 100%;
    height: auto;
    display: block;
}

/* 区块 7：常见问题 FAQ 区块 (FAQ Section) */
.faq-container {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    background-color: var(--color-dark-surface);
    border-radius: 6px;
    margin-bottom: 16px;
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.faq-item details {
    width: 100%;
}

.faq-item summary {
    padding: 24px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    list-style: none;
    position: relative;
    outline: none;
    user-select: none;
}

.faq-item summary::-webkit-details-marker {
    display: none;
}

.faq-item summary::after {
    content: '+';
    position: absolute;
    right: 24px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 1.5rem;
    color: var(--color-primary);
    transition: var(--transition-smooth);
}

.faq-item details[open] summary::after {
    content: '−';
    transform: translateY(-50%) rotate(180deg);
}

.faq-content {
    padding: 0 24px 24px 24px;
    color: var(--color-text-muted);
    font-size: 0.975rem;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    line-height: 1.7;
}

/* 区块 8：终极行动呼吁 (Final CTA Form) */
.cta-form-container {
    max-width: 650px;
    margin: 0 auto;
    background-color: var(--color-dark-surface);
    padding: 50px 40px;
    border-radius: 12px;
    border: 1px solid rgba(243, 156, 18, 0.2);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.form-group-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 20px;
}

.form-group {
    margin-bottom: 20px;
    display: flex;
    flex-direction: column;
}

.form-group label {
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--color-text-light);
}

.form-control {
    background-color: var(--color-dark-bg);
    border: 1px solid rgba(255, 255, 255, 0.15);
    padding: 14px 16px;
    color: var(--color-text-light);
    font-family: var(--font-sans);
    font-size: 0.95rem;
    border-radius: 4px;
    transition: var(--transition-smooth);
}

.form-control:focus {
    border-color: var(--color-primary);
    outline: none;
    box-shadow: 0 0 0 3px rgba(243, 156, 18, 0.15);
}

textarea.form-control {
    resize: vertical;
    min-height: 120px;
}

.form-submit-btn {
    width: 100%;
    padding: 16px;
    font-size: 1.1rem;
    margin-top: 10px;
}

/* 区块 9：专业级页尾 (Footer Section) */
.footer-section {
    background-color: #0F0F0F;
    padding: 80px 0 30px 0;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1.5fr;
    gap: 50px;
    margin-bottom: 60px;
}

.footer-brand-box .footer-logo {
    font-size: 1.4rem;
    font-weight: 800;
    color: var(--color-text-light);
    margin-bottom: 20px;
}

.footer-brand-box .footer-logo span {
    color: var(--color-primary);
}

.footer-brand-box p {
    color: var(--color-text-muted);
    font-size: 0.9rem;
    max-width: 320px;
}

.footer-links h4, .footer-contact h4 {
    font-size: 1.1rem;
    margin-bottom: 20px;
    position: relative;
}

.footer-links ul {
    list-style: none;
}

.footer-links ul li {
    margin-bottom: 12px;
}

.footer-links ul a {
    color: var(--color-text-muted);
    text-decoration: none;
    font-size: 0.9rem;
    transition: var(--transition-smooth);
}

.footer-links ul a:hover {
    color: var(--color-primary);
    padding-left: 4px;
}

.footer-contact p {
    color: var(--color-text-muted);
    font-size: 0.9rem;
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.footer-contact .hotline {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-top: 5px;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    padding-top: 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
    font-size: 0.85rem;
    color: var(--color-text-muted);
}

.footer-bottom a {
    color: var(--color-text-muted);
    text-decoration: none;
    transition: var(--transition-smooth);
}

.footer-bottom a:hover {
    color: var(--color-primary);
}

/* --------------------------------------------------------------------------
   5. 行动装置优先断点适配 (Mobile Responsive - RWD)
   -------------------------------------------------------------------------- */

/* 平板与大屏手机断点 (Max-width: 992px) */
@media (max-width: 992px) {
    .section {
        padding: 70px 0;
    }
    
    .hero-title {
        font-size: 2.8rem;
    }
    
    .about-wrapper {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .about-img-box {
        order: -1; /* 图像上移提高移动体验 */
    }
    
    .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: 40px;
    }
    
    .footer-brand-box {
        grid-column: span 2;
    }
}

/* ==========================================================================
   移动设备核心断点 - 绝对防穿透、防错位架构重构 (Max-width: 768px)
   ========================================================================== */
@media (max-width: 768px) {
    /* 1. 强制提升顶栏为全页绝对最高层级，切断任何下方元素的穿透可能 */
    .header-nav {
        position: sticky;
        top: 0;
        background-color: #1A1A1A; /* 移动端用纯色压实背景，防止毛玻璃半透明导致下方文字隐现 */
        height: 70px; /* 稍微收紧移动端高度 */
    }

    .nav-container {
        height: 100%;
    }

    .menu-toggle {
        display: flex; /* 确保汉堡按钮可见 */
    }
    
    /* 2. 重构菜单面板：改用全屏硬隔离容器，防止底层内容在缝隙中露头 */
    .nav-menu {
        position: fixed;
        top: 70px; /* 必须严丝合缝地等于 .header-nav 的 height */
        left: 0;
        width: 100vw;
        height: calc(100vh - 70px); /* 动态计算，完美占满除顶栏外的剩余全屏 */
        background-color: #1A1A1A;  /* 使用纯黑不透明背景，100%遮挡下方卡片 */
        
        /* 排版布局重设 */
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: flex-start; /* 从上往下排列，防长屏手机越界 */
        padding: 60px 24px;
        gap: 32px;
        
        /* 局部滚动保障：如果菜单项或按钮超长，允许内部滚动，但绝不穿透到底层 */
        overflow-y: auto;
        -webkit-overflow-scrolling: touch;
        
        /* 状态控制 */
        z-index: 99998 !important; /* 仅次于顶栏的最高层级 */
        transform: translateX(100%); /* 移动端最佳实践：改用左右滑入，彻底避免上下拉动时的卡顿错位 */
        opacity: 0;
        pointer-events: none;
        transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.2s linear;
    }
    
    /* 3. 激活状态：丝滑滑入并锁死指针交互 */
    .nav-menu.active {
        transform: translateX(0);
        opacity: 1;
        pointer-events: auto;
    }

    /* 4. 优化移动端菜单链接的点击热区与视觉阻力 */
    .nav-link {
        font-size: 1.3rem; /* 增大字号利于手指触摸 */
        font-weight: 600;
        color: #FFFFFF;
        padding: 12px 0;
        width: 100%;
        text-align: center;
        border-bottom: 1px solid rgba(255, 255, 255, 0.05); /* 增加极细分割线，建立秩序感 */
    }

    .nav-link::after {
        display: none; /* 移动端移除下划线动画，改用整行变色 */
    }

    .nav-link:hover, .nav-link.active {
        color: var(--color-primary);
        background-color: rgba(243, 156, 18, 0.05);
    }
    
    /* 5. 将 PC 端的常驻 CTA 按钮在移动端重塑，塞入菜单底部作为终极视觉收尾 */
    .header-nav .btn-nav-cta {
        display: flex;
        width: 100%;
        margin-top: 20px;
        padding: 16px;
        font-size: 1.1rem;
    }
    
    /* 6. 顺带修复其余区块在移动端的常规流间距错乱问题 */
    .hero-title {
        font-size: 2.2rem;
        line-height: 1.3;
    }
    
    .hero-cta-group {
        flex-direction: column;
        width: 100%;
    }
    
    .hero-cta-group .btn {
        width: 100%;
    }
    
    .form-group-row {
        grid-template-columns: 1fr;
        gap: 0;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-brand-box {
        grid-column: span 1;
    }
    
    .footer-bottom {
        flex-direction: column;
        text-align: center;
        gap: 10px;
    }
}

/* 汉堡按钮过渡动画逻辑 */
.menu-toggle.open span:nth-child(1) {
    transform: rotate(45deg) translate(6px, 6px);
}
.menu-toggle.open span:nth-child(2) {
    opacity: 0;
}
.menu-toggle.open span:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
}