/* ==================== 基础重置与变量 ==================== */
:root {
    --primary: #1a73e8;
    --primary-dark: #0d47a1;
    --primary-light: #42a5f5;
    --secondary: #00a896;
    --secondary-light: #4db6ac;
    --accent: #26c6da;
    --success: #4caf50;
    --danger: #f44336;
    --text-primary: #1a1a2e;
    --text-secondary: #4a4a68;
    --text-light: #8a8aa0;
    --bg-white: #ffffff;
    --bg-light: #f5f7fa;
    --bg-dark: #1a2332;
    --border: #e4e7ed;
    --border-light: #f0f2f5;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.12);
    --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.16);
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --max-width: 1200px;
    --header-height: 72px;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--header-height);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
    font-size: 16px;
    line-height: 1.7;
    color: var(--text-primary);
    background: var(--bg-white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

a:hover {
    color: var(--primary-dark);
}

ul, ol {
    list-style: none;
}

button {
    border: none;
    background: none;
    cursor: pointer;
    font-family: inherit;
}

input, select, textarea {
    font-family: inherit;
    font-size: inherit;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ==================== 头部导航 ==================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid transparent;
    z-index: 1000;
    transition: all var(--transition);
}

.header.scrolled {
    border-bottom-color: var(--border);
    box-shadow: var(--shadow-sm);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--primary);
}

.logo-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: #fff;
    border-radius: var(--radius-md);
}

.logo-text {
    display: flex;
    flex-direction: column;
    line-height: 1.2;
}

.logo-name {
    font-size: 18px;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: 0.5px;
}

.logo-sub {
    font-size: 10px;
    color: var(--text-light);
    letter-spacing: 1.5px;
    font-weight: 500;
}

.nav-list {
    display: flex;
    gap: 8px;
}

.nav-link {
    position: relative;
    display: block;
    padding: 8px 18px;
    font-size: 15px;
    font-weight: 500;
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    transition: color var(--transition), background var(--transition);
}

.nav-link::after {
    content: "";
    position: absolute;
    bottom: 4px;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: 2px;
    transition: width var(--transition);
}

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

.nav-link.active::after {
    width: 24px;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    width: 36px;
    height: 36px;
    padding: 8px;
    border-radius: var(--radius-sm);
    transition: background var(--transition);
}

.nav-toggle:hover {
    background: var(--bg-light);
}

.nav-toggle span {
    display: block;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all var(--transition);
}

/* ==================== 按钮 ==================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 32px;
    font-size: 15px;
    font-weight: 600;
    border-radius: var(--radius-md);
    transition: all var(--transition);
    cursor: pointer;
    text-align: center;
    white-space: nowrap;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #fff;
    box-shadow: 0 4px 14px rgba(26, 115, 232, 0.35);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(26, 115, 232, 0.45);
    color: #fff;
}

.btn-outline {
    background: transparent;
    color: #fff;
    border: 2px solid rgba(255, 255, 255, 0.6);
}

.btn-outline:hover {
    background: rgba(255, 255, 255, 0.15);
    border-color: #fff;
    color: #fff;
    transform: translateY(-2px);
}

.btn-full {
    width: 100%;
}

/* ==================== 首屏 Hero ==================== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding-top: var(--header-height);
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, #0d47a1 0%, #1565c0 30%, #00a896 100%);
    z-index: -2;
}

.hero-bg::before {
    content: "";
    position: absolute;
    inset: 0;
    background-image:
        radial-gradient(circle at 20% 30%, rgba(255, 255, 255, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 80% 70%, rgba(0, 168, 150, 0.2) 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, rgba(255, 255, 255, 0.05) 0%, transparent 70%);
}

.hero-bg::after {
    content: "";
    position: absolute;
    inset: 0;
    background:
        linear-gradient(180deg, transparent 0%, rgba(0, 0, 0, 0.1) 100%);
}

.hero-overlay {
    position: absolute;
    inset: 0;
    background:
        url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.03'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
    pointer-events: none;
    z-index: -1;
}

.hero-content {
    text-align: center;
    color: #fff;
    padding: 60px 24px;
}

.hero-title {
    font-size: clamp(32px, 5vw, 56px);
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 24px;
    letter-spacing: 1px;
}

.title-line {
    display: block;
}

.title-line.accent {
    background: linear-gradient(90deg, #fff, var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(15px, 2vw, 18px);
    margin-bottom: 40px;
    opacity: 0.9;
    max-width: 640px;
    margin-left: auto;
    margin-right: auto;
}

.hero-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-bottom: 80px;
    flex-wrap: wrap;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: clamp(24px, 4vw, 56px);
    flex-wrap: wrap;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
}

.stat-num {
    font-size: clamp(28px, 3.5vw, 42px);
    font-weight: 800;
    line-height: 1;
}

.stat-suffix {
    font-size: clamp(18px, 2vw, 24px);
    font-weight: 600;
}

.stat-label {
    font-size: 14px;
    opacity: 0.8;
    letter-spacing: 1px;
}

.scroll-down {
    position: absolute;
    bottom: 32px;
    left: 50%;
    transform: translateX(-50%);
    width: 28px;
    height: 46px;
    border: 2px solid rgba(255, 255, 255, 0.5);
    border-radius: 14px;
    display: flex;
    justify-content: center;
    padding-top: 8px;
}

.scroll-down span {
    width: 4px;
    height: 8px;
    background: rgba(255, 255, 255, 0.8);
    border-radius: 2px;
    animation: scrollDown 2s ease-in-out infinite;
}

@keyframes scrollDown {
    0% { transform: translateY(0); opacity: 1; }
    100% { transform: translateY(16px); opacity: 0; }
}

/* ==================== Section 通用 ==================== */
.section {
    padding: 96px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 64px;
}

.section-tag {
    display: inline-block;
    font-size: 13px;
    font-weight: 600;
    color: var(--primary);
    letter-spacing: 3px;
    margin-bottom: 12px;
    padding: 4px 16px;
    background: rgba(26, 115, 232, 0.08);
    border-radius: 100px;
}

.section-title {
    font-size: clamp(28px, 3.5vw, 38px);
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--text-primary);
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: "";
    display: block;
    width: 48px;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: 3px;
    margin: 12px auto 0;
}

.section-desc {
    font-size: 16px;
    color: var(--text-light);
    max-width: 560px;
    margin: 0 auto;
}

/* ==================== 关于我们 ==================== */
.about {
    background: var(--bg-white);
}

.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 64px;
    align-items: center;
}

.about-image {
    position: relative;
}

.image-wrapper {
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-xl);
    aspect-ratio: 4/5;
    background: linear-gradient(135deg, var(--primary-light), var(--secondary-light));
    display: flex;
    align-items: center;
    justify-content: center;
}

.image-wrapper img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.about-badge {
    position: absolute;
    bottom: -24px;
    right: -16px;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #fff;
    padding: 20px 28px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    text-align: center;
}

.badge-num {
    display: block;
    font-size: 32px;
    font-weight: 800;
    line-height: 1;
}

.badge-text {
    font-size: 13px;
    opacity: 0.9;
    margin-top: 4px;
    display: block;
}

.about-heading {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--text-primary);
}

.about-text {
    font-size: 15px;
    color: var(--text-secondary);
    margin-bottom: 16px;
    line-height: 1.8;
}

.about-features {
    display: grid;
    gap: 16px;
    margin-top: 28px;
}

.feature-item {
    display: flex;
    align-items: flex-start;
    gap: 14px;
    padding: 16px;
    background: var(--bg-light);
    border-radius: var(--radius-md);
    transition: transform var(--transition), box-shadow var(--transition);
}

.feature-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.feature-icon {
    flex-shrink: 0;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, rgba(26, 115, 232, 0.1), rgba(0, 168, 150, 0.1));
    color: var(--primary);
    border-radius: var(--radius-md);
}

.feature-item h4 {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 2px;
}

.feature-item p {
    font-size: 13px;
    color: var(--text-light);
}

/* ==================== 经营范围 ==================== */
.business {
    background: var(--bg-light);
}

.business-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 32px;
}

.business-card {
    background: var(--bg-white);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: transform var(--transition), box-shadow var(--transition);
}

.business-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.card-header {
    padding: 28px;
    display: flex;
    align-items: center;
    gap: 16px;
    color: #fff;
}

.card-header.general {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
}

.card-header.license {
    background: linear-gradient(135deg, #e65100, #bf360c);
}

.card-icon {
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-md);
}

.card-header h3 {
    font-size: 20px;
    font-weight: 700;
}

.business-list {
    padding: 24px 28px;
    display: grid;
    gap: 12px;
}

.business-list li {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.6;
}

.dot {
    flex-shrink: 0;
    width: 8px;
    height: 8px;
    margin-top: 7px;
    background: var(--primary);
    border-radius: 50%;
}

.license-notice {
    display: flex;
    align-items: center;
    gap: 8px;
    margin: 0 28px 24px;
    padding: 12px 16px;
    background: #fff3e0;
    color: #e65100;
    border-radius: var(--radius-sm);
    font-size: 13px;
}

/* ==================== 服务项目 ==================== */
.services {
    background: var(--bg-white);
}

.services-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}

.service-card {
    padding: 36px 28px;
    background: var(--bg-white);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-lg);
    text-align: center;
    transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

.service-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-light);
}

.service-icon {
    width: 72px;
    height: 72px;
    margin: 0 auto 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, rgba(26, 115, 232, 0.08), rgba(0, 168, 150, 0.08));
    color: var(--primary);
    border-radius: 50%;
    transition: transform var(--transition), background var(--transition);
}

.service-card:hover .service-icon {
    transform: scale(1.05);
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: #fff;
}

.service-card h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 12px;
}

.service-card > p {
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 20px;
    line-height: 1.7;
}

.service-features {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    justify-content: center;
}

.service-features li {
    font-size: 12px;
    padding: 4px 12px;
    background: var(--bg-light);
    color: var(--text-secondary);
    border-radius: 100px;
}

/* ==================== 产品展示 ==================== */
.products {
    background: var(--bg-light);
}

.products-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.product-card {
    background: var(--bg-white);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition), box-shadow var(--transition);
}

.product-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.product-image {
    position: relative;
    aspect-ratio: 4/3;
    background: linear-gradient(135deg, var(--primary-light), var(--secondary-light));
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.product-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s ease;
}

.product-card:hover .product-image img {
    transform: scale(1.05);
}

.product-tag {
    position: absolute;
    top: 12px;
    right: 12px;
    padding: 4px 12px;
    font-size: 12px;
    font-weight: 600;
    color: #fff;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    border-radius: 100px;
}

.product-info {
    padding: 20px;
}

.product-info h3 {
    font-size: 17px;
    font-weight: 700;
    margin-bottom: 8px;
}

.product-info p {
    font-size: 13px;
    color: var(--text-light);
    margin-bottom: 14px;
    line-height: 1.6;
}

.product-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.category {
    font-size: 12px;
    color: var(--primary);
    font-weight: 500;
    padding: 2px 10px;
    background: rgba(26, 115, 232, 0.08);
    border-radius: 100px;
}

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

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

/* ==================== 企业资质 ==================== */
.qualifications {
    background: var(--bg-white);
}

.quals-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    margin-bottom: 32px;
}

.qual-card {
    text-align: center;
    padding: 32px 20px;
    background: var(--bg-white);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-lg);
    transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

.qual-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary-light);
}

.qual-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, rgba(26, 115, 232, 0.1), rgba(0, 168, 150, 0.1));
    color: var(--primary);
    border-radius: 50%;
}

.qual-card h3 {
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 6px;
}

.qual-card p {
    font-size: 13px;
    color: var(--text-light);
}

.compliance-notice {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    max-width: 720px;
    margin: 0 auto;
    padding: 16px 24px;
    background: linear-gradient(135deg, rgba(26, 115, 232, 0.05), rgba(0, 168, 150, 0.05));
    border: 1px solid rgba(26, 115, 232, 0.15);
    border-radius: var(--radius-md);
    font-size: 14px;
    color: var(--primary-dark);
}

/* ==================== 联系方式 ==================== */
.contact {
    background: linear-gradient(135deg, var(--bg-light) 0%, #eef2f7 100%);
}

.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1.2fr;
    gap: 48px;
    align-items: start;
}

.contact-info {
    display: grid;
    gap: 20px;
}

.info-item {
    display: flex;
    gap: 16px;
    padding: 20px 24px;
    background: var(--bg-white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    transition: transform var(--transition), box-shadow var(--transition);
}

.info-item:hover {
    transform: translateX(4px);
    box-shadow: var(--shadow-md);
}

.info-icon {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, rgba(26, 115, 232, 0.1), rgba(0, 168, 150, 0.1));
    color: var(--primary);
    border-radius: var(--radius-md);
}

.info-item h4 {
    font-size: 15px;
    font-weight: 600;
    margin-bottom: 4px;
}

.info-item p {
    font-size: 14px;
    color: var(--text-light);
}

.contact-form {
    background: var(--bg-white);
    padding: 36px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.contact-form h3 {
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 8px;
}

.form-desc {
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 28px;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.form-group {
    margin-bottom: 18px;
}

.form-group label {
    display: block;
    font-size: 14px;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-secondary);
}

.required {
    color: var(--danger);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 12px 16px;
    font-size: 14px;
    color: var(--text-primary);
    background: var(--bg-light);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    transition: border-color var(--transition), box-shadow var(--transition);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(26, 115, 232, 0.12);
    background: var(--bg-white);
}

.form-group input::placeholder,
.form-group textarea::placeholder {
    color: var(--text-light);
}

.form-tip {
    display: flex;
    align-items: center;
    gap: 6px;
    margin-top: 16px;
    font-size: 12px;
    color: var(--text-light);
}

/* ==================== 页脚 ==================== */
.footer {
    background: var(--bg-dark);
    color: rgba(255, 255, 255, 0.7);
    padding-top: 64px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr 1fr;
    gap: 40px;
    padding-bottom: 48px;
}

.footer-col h4 {
    color: #fff;
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 20px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.footer-logo svg {
    color: var(--primary-light);
}

.footer-logo-name {
    font-size: 17px;
    font-weight: 700;
    color: #fff;
}

.footer-desc {
    font-size: 14px;
    line-height: 1.8;
    margin-bottom: 20px;
}

.footer-links {
    display: grid;
    gap: 10px;
}

.footer-links a {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.6);
    transition: color var(--transition), padding-left var(--transition);
}

.footer-links a:hover {
    color: #fff;
    padding-left: 4px;
}

.footer-contact {
    display: grid;
    gap: 14px;
}

.footer-contact li {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    font-size: 14px;
}

.footer-contact svg {
    flex-shrink: 0;
    margin-top: 2px;
    color: var(--secondary-light);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.08);
    padding: 24px 0;
    text-align: center;
}

.footer-bottom p {
    font-size: 13px;
    color: rgba(255, 255, 255, 0.5);
    line-height: 1.8;
}

/* ==================== 返回顶部 ==================== */
.back-top {
    position: fixed;
    right: 24px;
    bottom: 24px;
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #fff;
    border-radius: 50%;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(16px);
    transition: all var(--transition);
    z-index: 999;
}

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

.back-top:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

/* ==================== 动画 ==================== */
.fade-in-up {
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 0.8s ease forwards;
}

.fade-in-up.delay-1 {
    animation-delay: 0.15s;
}

.fade-in-up.delay-2 {
    animation-delay: 0.3s;
}

.fade-in-up.delay-3 {
    animation-delay: 0.45s;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.8s ease, transform 0.8s ease;
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ==================== 响应式 ==================== */
@media (max-width: 1024px) {
    .products-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .quals-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .services-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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

@media (max-width: 900px) {
    .about-grid,
    .business-grid,
    .contact-grid {
        grid-template-columns: 1fr;
    }

    .about-badge {
        right: 24px;
    }

    .section {
        padding: 72px 0;
    }
}

@media (max-width: 768px) {
    :root {
        --header-height: 60px;
    }

    .nav-toggle {
        display: flex;
    }

    .nav {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        background: #fff;
        border-bottom: 1px solid var(--border);
        padding: 16px;
        transform: translateY(-120%);
        transition: transform var(--transition);
        box-shadow: var(--shadow-md);
    }

    .nav.open {
        transform: translateY(0);
    }

    .nav-list {
        flex-direction: column;
        gap: 4px;
    }

    .nav-link {
        padding: 12px 16px;
        font-size: 15px;
    }

    .nav-link::after {
        display: none;
    }

    .hero-actions {
        margin-bottom: 60px;
    }

    .stat-item {
        gap: 2px;
    }

    .section {
        padding: 64px 0;
    }

    .section-header {
        margin-bottom: 48px;
    }

    .services-grid,
    .products-grid,
    .quals-grid {
        grid-template-columns: 1fr;
    }

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

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .footer-bottom {
        text-align: left;
    }

    .contact-form {
        padding: 28px 20px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

    .hero-content {
        padding: 40px 16px;
    }

    .btn {
        padding: 12px 24px;
        font-size: 14px;
    }

    .hero-stats {
        gap: 20px;
    }

    .about-badge {
        right: 0;
        bottom: -16px;
        padding: 16px 20px;
    }

    .compliance-notice {
        flex-direction: column;
        text-align: center;
    }
}

/* ==================== 打印 ==================== */
@media print {
    .header,
    .hero,
    .nav-toggle,
    .back-top,
    .scroll-down {
        display: none;
    }

    .section {
        padding: 32px 0;
        page-break-inside: avoid;
    }
}