/* ============================================
   喜雀集团官网 - 主样式表
   设计风格：专业官方 · 深蓝金色 · 简洁严谨
   ============================================ */

/* ---------- CSS变量与设计系统 ---------- */
:root {
    --color-primary: #0a1628;
    --color-secondary: #0d1b30;
    --color-tertiary: #152238;
    --color-accent: #d4af37;
    --color-accent-light: #e8c85a;
    --color-accent-dark: #b8941f;
    --color-text-primary: #ffffff;
    --color-text-secondary: #94a3b8;
    --color-text-muted: #64748b;
    --color-border: rgba(255, 255, 255, 0.08);
    --color-border-light: rgba(255, 255, 255, 0.12);
    --color-card-bg: rgba(255, 255, 255, 0.03);
    --color-card-hover: rgba(255, 255, 255, 0.06);
    
    --gradient-gold: linear-gradient(135deg, #d4af37 0%, #e8c85a 50%, #d4af37 100%);
    --gradient-hero: linear-gradient(135deg, #0a1628 0%, #0f2340 50%, #0a1628 100%);
    --gradient-dark: linear-gradient(180deg, #0a1628 0%, #0d1b30 100%);
    
    --font-main: 'PingFang SC', 'Microsoft YaHei', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    
    --nav-height: 68px;
    --container-max: 1280px;
    
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.15);
    
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* ---------- Reset & Base ---------- */
* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
    font-family: var(--font-main);
    background-color: var(--color-primary);
    color: var(--color-text-primary);
    line-height: 1.6;
    font-size: 15px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

a { color: inherit; text-decoration: none; transition: var(--transition-fast); }
a:hover { color: var(--color-accent); }

ul { list-style: none; }
img { max-width: 100%; display: block; }
button { font-family: inherit; cursor: pointer; border: none; background: none; color: inherit; }

/* ---------- Container ---------- */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 32px;
}

/* ---------- Section 通用 ---------- */
.section {
    padding: 80px 0;
}
.section-alt {
    background-color: var(--color-secondary);
}

.section-header {
    margin-bottom: 48px;
    max-width: 680px;
}
.section-header-center {
    text-align: center;
    margin-left: auto;
    margin-right: auto;
}

.section-label {
    display: inline-block;
    font-size: 13px;
    font-weight: 500;
    color: var(--color-accent);
    letter-spacing: 2px;
    margin-bottom: 12px;
    text-transform: uppercase;
}

.section-title {
    font-size: 32px;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 16px;
    color: var(--color-text-primary);
}

.section-subtitle {
    font-size: 15px;
    color: var(--color-text-secondary);
    line-height: 1.7;
}

.section-more {
    text-align: center;
    margin-top: 40px;
}

/* ---------- 按钮 ---------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 28px;
    font-size: 14px;
    font-weight: 500;
    border-radius: 6px;
    transition: var(--transition-fast);
    cursor: pointer;
    border: 1px solid transparent;
    white-space: nowrap;
}

.btn-sm { padding: 8px 20px; font-size: 13px; }
.btn-lg { padding: 14px 36px; font-size: 15px; }

.btn-primary {
    background: var(--gradient-gold);
    color: var(--color-primary);
    border-color: var(--color-accent);
}
.btn-primary:hover {
    opacity: 0.92;
    transform: translateY(-1px);
    color: var(--color-primary);
    box-shadow: 0 4px 12px rgba(212, 175, 55, 0.3);
}

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

/* ---------- 导航栏 ---------- */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    z-index: 1000;
    background: rgba(10, 22, 40, 0.95);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
    transition: var(--transition-normal);
}

.navbar-inner {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 32px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 32px;
}

.logo {
    display: flex;
    align-items: center;
    flex-shrink: 0;
}
.logo-img {
    height: 40px;
    width: auto;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 4px;
    flex: 1;
    justify-content: center;
}

.nav-item {
    position: relative;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: 8px 16px;
    font-size: 14px;
    font-weight: 500;
    color: var(--color-text-secondary);
    border-radius: 4px;
    transition: var(--transition-fast);
}

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

.nav-link.active {
    color: var(--color-accent);
}

/* 下拉菜单 */
.nav-dropdown {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(8px);
    min-width: 260px;
    background: var(--color-tertiary);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: 8px;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-fast);
    box-shadow: var(--shadow-lg);
}

.nav-item:hover .nav-dropdown {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.dropdown-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    border-radius: 6px;
    transition: var(--transition-fast);
}
.dropdown-item:hover {
    background: var(--color-card-hover);
}
.di-icon { font-size: 24px; }
.di-title { font-size: 14px; font-weight: 500; color: var(--color-text-primary); }
.di-desc { font-size: 12px; color: var(--color-text-muted); margin-top: 2px; }

/* 右侧CTA */
.nav-cta {
    display: flex;
    align-items: center;
    gap: 16px;
    flex-shrink: 0;
}

.nav-phone-num {
    font-size: 14px;
    font-weight: 600;
    color: var(--color-accent);
    white-space: nowrap;
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 8px;
    cursor: pointer;
}
.mobile-menu-btn span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--color-text-primary);
    border-radius: 2px;
    transition: var(--transition-fast);
}

/* 移动端菜单 */
.mobile-menu-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1001;
    opacity: 0;
    transition: var(--transition-fast);
}
.mobile-menu-overlay.active {
    display: block;
    opacity: 1;
}

.mobile-menu {
    position: fixed;
    top: 0;
    right: -320px;
    width: 300px;
    height: 100vh;
    background: var(--color-secondary);
    z-index: 1002;
    padding: 24px;
    display: flex;
    flex-direction: column;
    transition: var(--transition-normal);
    overflow-y: auto;
}
.mobile-menu.active { right: 0; }

.mobile-nav-links {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 4px;
    margin-top: 16px;
}
.mobile-nav-link {
    padding: 14px 16px;
    font-size: 15px;
    color: var(--color-text-secondary);
    border-radius: 6px;
    transition: var(--transition-fast);
}
.mobile-nav-link:hover {
    background: var(--color-card-hover);
    color: var(--color-text-primary);
}

.mobile-menu-cta {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 24px;
    padding-top: 24px;
    border-top: 1px solid var(--color-border);
}

/* ---------- Hero 区域 ---------- */
.hero {
    position: relative;
    padding-top: calc(var(--nav-height) + 60px);
    padding-bottom: 80px;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background: var(--gradient-hero);
    z-index: 0;
}

.hero .container {
    position: relative;
    z-index: 1;
}

.hero-inner {
    display: grid;
    grid-template-columns: 1.1fr 1fr;
    gap: 60px;
    align-items: center;
}

.hero-left { max-width: 560px; }

.hero-tag {
    display: inline-block;
    font-size: 13px;
    color: var(--color-accent);
    letter-spacing: 1px;
    margin-bottom: 20px;
    padding-left: 12px;
    border-left: 3px solid var(--color-accent);
}

.hero-title {
    font-size: 44px;
    font-weight: 700;
    line-height: 1.25;
    margin-bottom: 20px;
    color: var(--color-text-primary);
}

.hero-title .accent {
    color: var(--color-accent);
}

.hero-desc {
    font-size: 16px;
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: 32px;
}

.hero-actions {
    display: flex;
    gap: 16px;
    margin-bottom: 48px;
}

.hero-stats {
    display: flex;
    align-items: center;
    gap: 32px;
}

.stat-item { text-align: left; }

.stat-num {
    font-size: 28px;
    font-weight: 700;
    color: var(--color-accent);
    line-height: 1;
    margin-bottom: 6px;
}

.stat-label {
    font-size: 13px;
    color: var(--color-text-muted);
}

.stat-divider {
    width: 1px;
    height: 36px;
    background: var(--color-border);
}

/* Hero右侧产品卡片 */
.hero-right {
    display: flex;
    justify-content: center;
}

.hero-product-card {
    width: 100%;
    max-width: 420px;
    background: var(--color-tertiary);
    border: 1px solid var(--color-border);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

.hpc-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    border-bottom: 1px solid var(--color-border);
}

.hpc-badge {
    font-size: 12px;
    color: var(--color-accent);
    font-weight: 500;
    padding: 4px 10px;
    border: 1px solid var(--color-accent);
    border-radius: 4px;
}

.hpc-name {
    font-size: 18px;
    font-weight: 600;
    color: var(--color-text-primary);
}

.hpc-body {
    padding: 28px 24px;
}

.hpc-features {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.hpc-feat {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 14px;
    background: var(--color-card-bg);
    border-radius: 6px;
    font-size: 13px;
    color: var(--color-text-secondary);
}

.hpc-feat-icon { font-size: 20px; }

.hpc-footer {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    border-top: 1px solid var(--color-border);
    background: var(--color-card-bg);
}

.hpc-metric {
    padding: 16px 12px;
    text-align: center;
}

.hpc-metric + .hpc-metric {
    border-left: 1px solid var(--color-border);
}

.hpc-metric-val {
    display: block;
    font-size: 18px;
    font-weight: 700;
    color: var(--color-accent);
    margin-bottom: 4px;
}

.hpc-metric-label {
    font-size: 12px;
    color: var(--color-text-muted);
}

/* ---------- 合作伙伴栏 ---------- */
.partners-bar {
    padding: 32px 0;
    background: var(--color-secondary);
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
}

.partners-bar-inner {
    display: flex;
    align-items: center;
    gap: 40px;
}

.partners-bar-label {
    flex-shrink: 0;
    font-size: 13px;
    color: var(--color-text-muted);
    letter-spacing: 1px;
}

.partners-bar-list {
    display: flex;
    align-items: center;
    gap: 36px;
    flex: 1;
    flex-wrap: wrap;
}

.partners-bar-list span {
    font-size: 14px;
    color: var(--color-text-secondary);
    font-weight: 500;
    white-space: nowrap;
}

/* ---------- 产品卡片 ---------- */
.product-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
}

.product-card {
    display: block;
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 10px;
    padding: 28px 24px;
    transition: var(--transition-normal);
}

.product-card:hover {
    border-color: var(--color-accent);
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
    color: inherit;
}

.pc-icon {
    font-size: 40px;
    margin-bottom: 16px;
}

.pc-title {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--color-text-primary);
}

.pc-desc {
    font-size: 13px;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 16px;
}

.pc-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 16px;
}

.pc-tags span {
    font-size: 11px;
    color: var(--color-text-muted);
    padding: 3px 8px;
    background: var(--color-card-hover);
    border-radius: 4px;
}

.pc-link {
    font-size: 13px;
    color: var(--color-accent);
    font-weight: 500;
}

/* ---------- 解决方案 ---------- */
.solution-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
}

.solution-card {
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 10px;
    padding: 28px 24px;
    transition: var(--transition-normal);
}

.solution-card:hover {
    border-color: var(--color-accent);
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.sc-icon { font-size: 36px; margin-bottom: 14px; }

.sc-title {
    font-size: 17px;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--color-text-primary);
}

.sc-desc {
    font-size: 13px;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 16px;
}

.sc-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.sc-list li {
    font-size: 13px;
    color: var(--color-text-secondary);
    padding-left: 16px;
    position: relative;
}

.sc-list li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 8px;
    width: 6px;
    height: 6px;
    background: var(--color-accent);
    border-radius: 50%;
}

/* ---------- 新闻资讯 ---------- */
.news-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.news-card {
    display: block;
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 10px;
    overflow: hidden;
    transition: var(--transition-normal);
}

.news-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
    color: inherit;
    border-color: var(--color-border-light);
}

.news-thumb {
    height: 180px;
    position: relative;
    display: flex;
    align-items: flex-start;
    padding: 16px;
}

.news-thumb-1 { background: linear-gradient(135deg, #1a3a5c 0%, #0d2137 100%); }
.news-thumb-2 { background: linear-gradient(135deg, #2a3a4c 0%, #15202d 100%); }
.news-thumb-3 { background: linear-gradient(135deg, #3a2f4c 0%, #1f1830 100%); }

.news-tag {
    display: inline-block;
    font-size: 11px;
    color: var(--color-accent);
    padding: 4px 10px;
    background: rgba(212, 175, 55, 0.1);
    border: 1px solid rgba(212, 175, 55, 0.2);
    border-radius: 4px;
    font-weight: 500;
}

.news-body { padding: 20px 24px 24px; }

.news-title {
    font-size: 16px;
    font-weight: 600;
    line-height: 1.5;
    margin-bottom: 10px;
    color: var(--color-text-primary);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.news-excerpt {
    font-size: 13px;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 14px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.news-meta {
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    color: var(--color-text-muted);
}

/* ---------- 合作案例 ---------- */
.case-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.case-card {
    background: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 10px;
    overflow: hidden;
    transition: var(--transition-normal);
}

.case-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-border-light);
}

.case-thumb {
    height: 160px;
    position: relative;
    display: flex;
    align-items: flex-start;
    padding: 16px;
}

.case-thumb-1 { background: linear-gradient(135deg, #1e3a5f 0%, #0f1d30 100%); }
.case-thumb-2 { background: linear-gradient(135deg, #2a2f4a 0%, #161a2e 100%); }
.case-thumb-3 { background: linear-gradient(135deg, #1f3d3a 0%, #0e2321 100%); }
.case-thumb-4 { background: linear-gradient(135deg, #3a2a3a 0%, #1f1520 100%); }
.case-thumb-5 { background: linear-gradient(135deg, #3a3520 0%, #201d10 100%); }
.case-thumb-6 { background: linear-gradient(135deg, #253a2a 0%, #121f15 100%); }

.case-tag {
    display: inline-block;
    font-size: 11px;
    color: var(--color-accent);
    padding: 4px 10px;
    background: rgba(212, 175, 55, 0.1);
    border: 1px solid rgba(212, 175, 55, 0.2);
    border-radius: 4px;
    font-weight: 500;
}

.case-body { padding: 20px 24px 24px; }

.case-title {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--color-text-primary);
}

.case-desc {
    font-size: 13px;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 16px;
}

.case-metrics {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
    padding-top: 14px;
    border-top: 1px solid var(--color-border);
}

.case-metric {
    text-align: center;
}

.cm-val {
    display: block;
    font-size: 15px;
    font-weight: 700;
    color: var(--color-accent);
    margin-bottom: 2px;
}

.cm-label {
    font-size: 11px;
    color: var(--color-text-muted);
}

/* ---------- 关于我们 ---------- */
.about-row {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 60px;
    align-items: center;
}

.about-left .section-header { margin-bottom: 24px; }

.about-desc {
    font-size: 15px;
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: 28px;
}

.about-highlights {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 32px;
}

.ah-item {
    display: flex;
    gap: 14px;
    padding: 16px;
    background: var(--color-card-bg);
    border-radius: 8px;
    border: 1px solid var(--color-border);
}

.ah-num {
    flex-shrink: 0;
    font-size: 24px;
    font-weight: 700;
    color: var(--color-accent);
    line-height: 1;
}

.ah-item h4 {
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 4px;
    color: var(--color-text-primary);
}

.ah-item p {
    font-size: 12px;
    color: var(--color-text-muted);
    line-height: 1.5;
}

.about-right { display: flex; justify-content: center; }

.about-image-placeholder {
    width: 100%;
    max-width: 380px;
    aspect-ratio: 4/3;
    background: var(--gradient-hero);
    border: 1px solid var(--color-border);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.aip-content {
    text-align: center;
}

.aip-logo {
    display: block;
    font-size: 36px;
    font-weight: 800;
    color: var(--color-accent);
    margin-bottom: 8px;
}

.aip-sub {
    font-size: 14px;
    color: var(--color-text-muted);
    letter-spacing: 4px;
}

/* ---------- CTA 区块 ---------- */
.cta-section {
    padding: 60px 0;
    background: linear-gradient(135deg, var(--color-secondary) 0%, var(--color-tertiary) 100%);
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
}

.cta-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 40px;
}

.cta-left { flex: 1; }

.cta-title {
    font-size: 26px;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--color-text-primary);
}

.cta-desc {
    font-size: 14px;
    color: var(--color-text-secondary);
}

.cta-right {
    display: flex;
    align-items: center;
    gap: 28px;
    flex-shrink: 0;
}

.cta-phone { text-align: right; }

.cta-phone-label {
    display: block;
    font-size: 12px;
    color: var(--color-text-muted);
    margin-bottom: 4px;
}

.cta-phone-num {
    font-size: 20px;
    font-weight: 700;
    color: var(--color-accent);
}

/* ---------- 页脚 ---------- */
.footer {
    background: var(--color-primary);
    padding: 56px 0 24px;
    border-top: 1px solid var(--color-border);
}

.footer-grid {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr 1fr 1.2fr;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-logo {
    height: 36px;
    width: auto;
    margin-bottom: 14px;
}

.footer-slogan {
    font-size: 14px;
    font-weight: 600;
    color: var(--color-text-primary);
    margin-bottom: 8px;
}

.footer-desc {
    font-size: 13px;
    color: var(--color-text-muted);
    line-height: 1.7;
}

.footer-col-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--color-text-primary);
    margin-bottom: 18px;
}

.footer-links {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.footer-links a {
    font-size: 13px;
    color: var(--color-text-secondary);
    transition: var(--transition-fast);
}

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

.footer-contact {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-contact li {
    font-size: 13px;
    color: var(--color-text-secondary);
    display: flex;
    gap: 8px;
    align-items: flex-start;
    line-height: 1.5;
}

.footer-contact li span:first-child {
    flex-shrink: 0;
}

.footer-bottom {
    padding-top: 24px;
    border-top: 1px solid var(--color-border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 12px;
    color: var(--color-text-muted);
}

.footer-bottom a {
    color: var(--color-text-muted);
    transition: var(--transition-fast);
}
.footer-bottom a:hover { color: var(--color-accent); }

/* ---------- 回到顶部 ---------- */
.back-to-top {
    position: fixed;
    right: 24px;
    bottom: 100px;
    width: 44px;
    height: 44px;
    border-radius: 8px;
    background: var(--color-tertiary);
    border: 1px solid var(--color-border);
    color: var(--color-text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: var(--transition-fast);
    z-index: 99;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
}

/* ---------- 响应式 ---------- */
@media (max-width: 1200px) {
    .product-grid { grid-template-columns: repeat(2, 1fr); }
    .solution-grid { grid-template-columns: repeat(2, 1fr); }
    .case-grid { grid-template-columns: repeat(2, 1fr); }
    .footer-grid { grid-template-columns: repeat(3, 1fr); }
    .footer-brand { grid-column: span 3; }
}

@media (max-width: 992px) {
    :root { --nav-height: 60px; }
    
    .nav-menu { display: none; }
    .mobile-menu-btn { display: flex; }
    .nav-phone-num { display: none; }
    
    .hero-inner {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    .hero-left { max-width: 100%; }
    .hero-title { font-size: 32px; }
    .hero-right { order: -1; }
    .hero-product-card { max-width: 100%; }
    
    .about-row {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .cta-inner {
        flex-direction: column;
        text-align: center;
    }
    .cta-right { flex-direction: column; }
    .cta-phone { text-align: center; }
}

@media (max-width: 768px) {
    .container { padding: 0 20px; }
    .section { padding: 56px 0; }
    .section-title { font-size: 24px; }
    
    .hero-title { font-size: 28px; }
    .hero-desc { font-size: 14px; }
    .hero-stats { gap: 20px; flex-wrap: wrap; }
    .stat-num { font-size: 22px; }
    
    .partners-bar-inner { flex-direction: column; gap: 16px; align-items: flex-start; }
    .partners-bar-list { gap: 16px; }
    .partners-bar-list span { font-size: 12px; }
    
    .product-grid,
    .solution-grid,
    .case-grid,
    .news-grid {
        grid-template-columns: 1fr;
    }
    
    .about-highlights { grid-template-columns: 1fr; }
    
    .footer-grid { grid-template-columns: 1fr 1fr; }
    .footer-brand { grid-column: span 2; }
    .footer-bottom { flex-direction: column; gap: 8px; text-align: center; }
}

@media (max-width: 480px) {
    .hero-actions { flex-direction: column; }
    .hero-actions .btn { width: 100%; }
    .footer-grid { grid-template-columns: 1fr; }
    .footer-brand { grid-column: span 1; }
    .hpc-features { grid-template-columns: 1fr; }
    .case-metrics { grid-template-columns: 1fr; gap: 12px; }
    .case-metric + .case-metric { border-left: none; border-top: 1px solid var(--color-border); padding-top: 12px; }
}