/* ============================================
   丹阳市天辰汽车配件有限公司 Landing Page
   Premium Dark Theme with Modern Aesthetics
   ============================================ */

/* === CSS Variables === */
:root {
    --color-bg: #0a0a0f;
    --color-bg-alt: #10111a;
    --color-bg-card: #161824;
    --color-bg-card-hover: #1e2030;
    --color-surface: #14152080;
    --color-border: rgba(255, 255, 255, 0.06);
    --color-border-hover: rgba(255, 255, 255, 0.12);

    --color-primary: #0A8FE6;
    --color-primary-light: #3AABF7;
    --color-primary-dark: #0872B8;
    --color-accent: #0A8FE6;
    --color-accent-light: #3AABF7;

    --color-text: #f1f5f9;
    --color-text-secondary: #94a3b8;
    --color-text-muted: #64748b;

    --gradient-primary: linear-gradient(135deg, #0A8FE6, #0668B0);
    --gradient-accent: linear-gradient(135deg, #0A8FE6, #065A9E);
    --gradient-dark: linear-gradient(180deg, rgba(10,10,15,0) 0%, rgba(10,10,15,1) 100%);
    --gradient-card: linear-gradient(145deg, rgba(10,143,230,0.05), rgba(6,104,176,0.05));

    --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
    --shadow-md: 0 8px 32px rgba(0,0,0,0.4);
    --shadow-lg: 0 16px 64px rgba(0,0,0,0.5);
    --shadow-glow: 0 0 40px rgba(10,143,230,0.15);

    --font-sans: 'Inter', 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 28px;

    --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: var(--font-sans);
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.7;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

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

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

ul {
    list-style: none;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.section {
    padding: 100px 0;
    position: relative;
}

/* === Navigation === */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 16px 0;
    transition: all var(--transition-base);
    background: transparent;
}

.navbar.scrolled {
    background: rgba(10, 10, 15, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-border);
    padding: 10px 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    font-size: 1.1rem;
}

.logo-img {
    height: 32px;
    width: auto;
}

.footer-brand .logo-img {
    height: 28px;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-link {
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-text);
    background: rgba(255, 255, 255, 0.05);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: 2px;
    left: 50%;
    transform: translateX(-50%);
    width: 20px;
    height: 2px;
    background: var(--gradient-primary);
    border-radius: 2px;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--color-text);
    border-radius: 2px;
    transition: all var(--transition-fast);
}

/* === Hero Section === */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    z-index: 0;
}

.hero-bg-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    filter: brightness(0.35) saturate(0.8);
    transform: scale(1.05);
    animation: heroZoom 20s ease-in-out infinite alternate;
}

@keyframes heroZoom {
    0% { transform: scale(1.05); }
    100% { transform: scale(1.12); }
}

.hero-overlay {
    position: absolute;
    inset: 0;
    background: 
        linear-gradient(180deg, rgba(10,10,15,0.6) 0%, rgba(10,10,15,0.3) 40%, rgba(10,10,15,0.8) 100%),
        radial-gradient(ellipse at 30% 50%, rgba(10,143,230,0.1), transparent 60%);
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 850px;
    padding: 0 24px;
}

.hero-badge {
    display: inline-block;
    padding: 8px 20px;
    background: rgba(10, 143, 230, 0.1);
    border: 1px solid rgba(10, 143, 230, 0.2);
    border-radius: 100px;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--color-primary-light);
    margin-bottom: 28px;
    animation: fadeInUp 0.8s ease-out;
}

.hero-title {
    margin-bottom: 24px;
    animation: fadeInUp 0.8s ease-out 0.1s both;
}

.hero-title-cn {
    display: block;
    font-size: clamp(2rem, 5vw, 3.2rem);
    font-weight: 800;
    letter-spacing: 2px;
    line-height: 1.3;
    background: linear-gradient(135deg, #ffffff 0%, #e2e8f0 50%, #cbd5e1 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-title-en {
    display: block;
    font-size: clamp(0.85rem, 2vw, 1.1rem);
    font-weight: 400;
    color: var(--color-text-muted);
    margin-top: 8px;
    letter-spacing: 3px;
    text-transform: uppercase;
}

.hero-desc {
    font-size: 1.05rem;
    color: var(--color-text-secondary);
    line-height: 1.9;
    margin-bottom: 36px;
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

.hero-actions {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin-bottom: 60px;
    animation: fadeInUp 0.8s ease-out 0.3s both;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 28px;
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: all var(--transition-base);
    font-family: var(--font-sans);
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: 0 4px 16px rgba(10, 143, 230, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 32px rgba(10, 143, 230, 0.4);
}

.btn-outline {
    background: transparent;
    color: var(--color-text);
    border: 1px solid var(--color-border-hover);
}

.btn-outline:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

.btn-full {
    width: 100%;
    justify-content: center;
}

/* Hero Stats */
.hero-stats {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 40px;
    animation: fadeInUp 0.8s ease-out 0.4s both;
}

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

.stat-number {
    font-size: 2.2rem;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.stat-suffix {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-primary-light);
}

.stat-label {
    display: block;
    font-size: 0.8rem;
    color: var(--color-text-muted);
    margin-top: 4px;
    font-weight: 500;
}

.stat-divider {
    width: 1px;
    height: 40px;
    background: var(--color-border);
}

/* Hero Scroll */
.hero-scroll {
    position: absolute;
    bottom: 32px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: var(--color-text-muted);
    font-size: 0.75rem;
    letter-spacing: 2px;
    animation: fadeInUp 0.8s ease-out 0.6s both;
}

.scroll-indicator {
    width: 24px;
    height: 40px;
    border: 2px solid var(--color-text-muted);
    border-radius: 12px;
    position: relative;
}

.scroll-indicator::after {
    content: '';
    position: absolute;
    top: 6px;
    left: 50%;
    transform: translateX(-50%);
    width: 4px;
    height: 8px;
    background: var(--color-primary-light);
    border-radius: 4px;
    animation: scrollBounce 2s ease-in-out infinite;
}

@keyframes scrollBounce {
    0%, 100% { top: 6px; opacity: 1; }
    50% { top: 22px; opacity: 0.3; }
}

/* === Section Header === */
.section-header {
    text-align: center;
    margin-bottom: 64px;
}

.section-tag {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 4px;
    text-transform: uppercase;
    color: var(--color-primary-light);
    margin-bottom: 12px;
    position: relative;
}

.section-tag::before,
.section-tag::after {
    content: '';
    display: inline-block;
    width: 24px;
    height: 1px;
    background: var(--color-primary);
    vertical-align: middle;
    margin: 0 12px;
    opacity: 0.5;
}

.section-title {
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 800;
    margin-bottom: 12px;
    background: linear-gradient(135deg, #ffffff, #cbd5e1);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.section-subtitle {
    font-size: 1rem;
    color: var(--color-text-secondary);
    max-width: 500px;
    margin: 0 auto;
}

/* === About Section === */
.about-section {
    background: var(--color-bg-alt);
    overflow: hidden;
}

.about-section::before {
    content: '';
    position: absolute;
    top: -200px;
    right: -200px;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(10,143,230,0.06), transparent 70%);
    pointer-events: none;
}

.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: start;
}

.about-text {
    font-size: 0.95rem;
    color: var(--color-text-secondary);
    margin-bottom: 20px;
    line-height: 1.9;
}

.about-text strong {
    color: var(--color-text);
}

.about-text em {
    color: var(--color-accent-light);
    font-style: normal;
}

.about-highlights {
    display: flex;
    flex-direction: column;
    gap: 16px;
    margin-top: 32px;
}

.highlight-item {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 16px 20px;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
}

.highlight-item:hover {
    border-color: var(--color-border-hover);
    background: var(--color-bg-card-hover);
    transform: translateX(4px);
}

.highlight-icon {
    font-size: 1.5rem;
    flex-shrink: 0;
}

.highlight-item h4 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: 2px;
    color: var(--color-text);
}

.highlight-item p {
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

/* About Visual Cards */
.about-visual {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.about-card {
    padding: 28px 32px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.about-card::before {
    content: '';
    position: absolute;
    inset: 0;
    opacity: 0;
    transition: opacity var(--transition-base);
}

.about-card:hover::before {
    opacity: 1;
}

.about-card:hover {
    transform: translateY(-4px);
    border-color: var(--color-border-hover);
    box-shadow: var(--shadow-glow);
}

.about-card-1 {
    background: linear-gradient(145deg, rgba(10,143,230,0.08), rgba(10,143,230,0.02));
}
.about-card-1::before {
    background: linear-gradient(145deg, rgba(10,143,230,0.12), rgba(10,143,230,0.03));
}

.about-card-2 {
    background: linear-gradient(145deg, rgba(6,104,176,0.08), rgba(6,104,176,0.02));
}
.about-card-2::before {
    background: linear-gradient(145deg, rgba(6,104,176,0.12), rgba(6,104,176,0.03));
}

.about-card-3 {
    background: linear-gradient(145deg, rgba(58,171,247,0.08), rgba(58,171,247,0.02));
}
.about-card-3::before {
    background: linear-gradient(145deg, rgba(58,171,247,0.12), rgba(58,171,247,0.03));
}

.card-inner {
    position: relative;
    z-index: 1;
}

.card-number {
    font-size: 2.5rem;
    font-weight: 800;
    opacity: 0.08;
    position: absolute;
    top: -8px;
    right: 0;
    font-style: italic;
}

.about-card h3 {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.about-card p {
    font-size: 0.9rem;
    color: var(--color-text-secondary);
}

/* === Products Section === */
.products-section {
    background: var(--color-bg);
}

.products-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
    margin-bottom: 48px;
}

.product-card {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: all var(--transition-base);
    cursor: pointer;
}

.product-card:hover {
    transform: translateY(-6px);
    border-color: rgba(10, 143, 230, 0.2);
    box-shadow: var(--shadow-glow);
}

.product-image {
    position: relative;
    height: 240px;
    overflow: hidden;
    background: #0d0d14;
}

.product-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-slow);
}

.product-card:hover .product-image img {
    transform: scale(1.08);
}

.product-badge {
    position: absolute;
    top: 16px;
    right: 16px;
    padding: 4px 14px;
    font-size: 0.75rem;
    font-weight: 700;
    border-radius: 100px;
    background: var(--gradient-accent);
    color: white;
}

.product-info {
    padding: 24px;
}

.product-info h3 {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.product-info p {
    font-size: 0.88rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: 16px;
}

.product-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.product-tags span {
    padding: 4px 12px;
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: 100px;
    background: rgba(10, 143, 230, 0.08);
    color: var(--color-primary-light);
    border: 1px solid rgba(10, 143, 230, 0.15);
}

/* Products Brands */
.products-brands {
    text-align: center;
    padding: 40px;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
}

.products-brands h3 {
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 3px;
    text-transform: uppercase;
    color: var(--color-text-muted);
    margin-bottom: 24px;
}

.brands-list {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 12px;
}

.brand-item {
    padding: 10px 24px;
    font-size: 0.9rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--color-border);
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
}

.brand-item:hover {
    border-color: var(--color-primary);
    color: var(--color-text);
    background: rgba(10, 143, 230, 0.05);
    transform: translateY(-2px);
}

/* === Advantages Section === */
.advantages-section {
    background: var(--color-bg-alt);
    overflow: hidden;
}

.advantages-section::after {
    content: '';
    position: absolute;
    bottom: -200px;
    left: -200px;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(10,143,230,0.06), transparent 70%);
    pointer-events: none;
}

.advantages-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.advantage-card {
    padding: 36px 28px;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    text-align: center;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.advantage-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 2px;
    background: var(--gradient-primary);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.advantage-card:hover {
    transform: translateY(-6px);
    border-color: var(--color-border-hover);
    box-shadow: var(--shadow-glow);
}

.advantage-card:hover::before {
    opacity: 1;
}

.adv-icon {
    width: 56px;
    height: 56px;
    margin: 0 auto 20px;
    padding: 12px;
    background: rgba(10, 143, 230, 0.08);
    border-radius: var(--radius-md);
    color: var(--color-primary-light);
    transition: all var(--transition-base);
}

.advantage-card:hover .adv-icon {
    background: rgba(10, 143, 230, 0.15);
    transform: scale(1.1);
}

.advantage-card h3 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.advantage-card p {
    font-size: 0.88rem;
    color: var(--color-text-secondary);
    line-height: 1.7;
}

/* === Exhibition Section === */
.exhibition-section {
    background: var(--color-bg);
}

.exhibition-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.exhibition-item {
    padding: 28px 24px;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.exhibition-item::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--gradient-primary);
    transform: scaleX(0);
    transition: transform var(--transition-base);
}

.exhibition-item:hover {
    transform: translateY(-4px);
    border-color: var(--color-border-hover);
}

.exhibition-item:hover::after {
    transform: scaleX(1);
}

.exh-year {
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--color-primary-light);
    letter-spacing: 2px;
    margin-bottom: 8px;
}

.exhibition-item h3 {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 4px;
}

.exhibition-item p {
    font-size: 0.82rem;
    color: var(--color-text-muted);
}

/* === Contact Section === */
.contact-section {
    background: var(--color-bg-alt);
    overflow: hidden;
}

.contact-section::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(10,143,230,0.04), transparent 70%);
    pointer-events: none;
}

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

.contact-info-cards {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.contact-card {
    padding: 24px;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
}

.contact-card:hover {
    border-color: var(--color-border-hover);
    transform: translateY(-2px);
}

.contact-icon {
    width: 40px;
    height: 40px;
    padding: 8px;
    background: rgba(10, 143, 230, 0.08);
    border-radius: var(--radius-sm);
    color: var(--color-primary-light);
    margin-bottom: 14px;
}

.contact-card h4 {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--color-text-muted);
    margin-bottom: 6px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.contact-card p {
    font-size: 0.92rem;
    color: var(--color-text);
    word-break: break-all;
}

.contact-card a {
    color: var(--color-primary-light);
}

.contact-card a:hover {
    text-decoration: underline;
}

.contact-sub {
    font-size: 0.78rem !important;
    color: var(--color-text-muted) !important;
    margin-top: 4px;
}

/* Contact Form */
.contact-form-wrap {
    position: relative;
}

.contact-form {
    padding: 36px;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
}

.contact-form h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 24px;
}

.form-group {
    margin-bottom: 16px;
}

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

.contact-form input,
.contact-form textarea {
    width: 100%;
    padding: 14px 18px;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    color: var(--color-text);
    font-family: var(--font-sans);
    font-size: 0.9rem;
    transition: all var(--transition-fast);
    outline: none;
}

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

.contact-form input:focus,
.contact-form textarea:focus {
    border-color: var(--color-primary);
    background: rgba(10, 143, 230, 0.03);
    box-shadow: 0 0 0 3px rgba(10, 143, 230, 0.08);
}

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

/* === Footer === */
.footer {
    background: var(--color-bg);
    border-top: 1px solid var(--color-border);
    padding: 60px 0 30px;
}

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

.footer-brand p {
    margin-top: 16px;
    font-size: 0.88rem;
    color: var(--color-text-muted);
    line-height: 1.7;
}

.footer-links h4,
.footer-contact h4 {
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--color-text);
}

.footer-links ul {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.footer-links a {
    font-size: 0.88rem;
    color: var(--color-text-muted);
    transition: all var(--transition-fast);
}

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

.footer-contact p {
    font-size: 0.88rem;
    color: var(--color-text-muted);
    margin-bottom: 8px;
}

.footer-bottom {
    padding-top: 24px;
    border-top: 1px solid var(--color-border);
    text-align: center;
}

.footer-bottom p {
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

/* === Back to Top === */
.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    background: var(--gradient-primary);
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    box-shadow: var(--shadow-md);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--transition-base);
    z-index: 999;
}

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

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 32px rgba(10, 143, 230, 0.4);
}

.back-to-top svg {
    width: 20px;
    height: 20px;
}

/* === Animations === */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.7s cubic-bezier(0.4, 0, 0.2, 1);
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* === Responsive === */
@media (max-width: 1024px) {
    .about-grid {
        grid-template-columns: 1fr;
        gap: 40px;
    }

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

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

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

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

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

@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: rgba(10, 10, 15, 0.95);
        backdrop-filter: blur(20px);
        padding: 16px 24px;
        flex-direction: column;
        border-bottom: 1px solid var(--color-border);
    }

    .nav-links.active {
        display: flex;
    }

    .nav-toggle {
        display: flex;
    }

    .section {
        padding: 70px 0;
    }

    .hero-stats {
        flex-direction: column;
        gap: 20px;
    }

    .stat-divider {
        width: 40px;
        height: 1px;
    }

    .hero-actions {
        flex-direction: column;
        width: 100%;
    }

    .hero-actions .btn {
        width: 100%;
        justify-content: center;
    }

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

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

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

    .contact-info-cards {
        grid-template-columns: 1fr;
    }

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

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    .section-tag::before,
    .section-tag::after {
        width: 16px;
        margin: 0 8px;
    }

    .product-image {
        height: 200px;
    }
}

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

    .hero-title-cn {
        font-size: 1.6rem;
    }

    .contact-form {
        padding: 24px;
    }
}