/* ===================================
   CSS Variables & Reset
   =================================== */
:root {
    --color-primary: #2563eb;
    --color-primary-dark: #1d4ed8;
    --color-secondary: #0f172a;
    --color-text: #334155;
    --color-text-light: #64748b;
    --color-bg: #ffffff;
    --color-bg-alt: #f8fafc;
    --color-border: #e2e8f0;
    --color-white: #ffffff;

    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;

    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;

    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);

    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-family);
    color: var(--color-text);
    line-height: 1.6;
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

ul {
    list-style: none;
}

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

/* ===================================
   Container
   =================================== */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ===================================
   Navigation
   =================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    transition: var(--transition);
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-sm) var(--spacing-md);
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-secondary);
    letter-spacing: -0.02em;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.nav-links a {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--color-text);
    position: relative;
    padding: var(--spacing-xs) 0;
}

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

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

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

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

.menu-toggle span {
    width: 25px;
    height: 2px;
    background: var(--color-secondary);
    transition: var(--transition);
}

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

.hero-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('../images/bg-home.jpg') center/cover no-repeat;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(15, 23, 42, 0.9) 0%, rgba(37, 99, 235, 0.8) 100%);
}

.hero-content {
    position: relative;
    z-index: 1;
    padding-top: 80px;
}

.hero-title {
    font-size: clamp(2.5rem, 6vw, 4.5rem);
    font-weight: 700;
    color: var(--color-white);
    line-height: 1.1;
    letter-spacing: -0.03em;
    margin-bottom: var(--spacing-md);
    overflow: hidden;
}

.hero-title .line {
    display: block;
    opacity: 0;
    transform: translateY(100%);
    animation: slideUp 0.8s ease forwards;
}

.hero-title .line:nth-child(2) {
    animation-delay: 0.2s;
}

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

.hero-subtitle {
    font-size: clamp(1rem, 2vw, 1.25rem);
    color: rgba(255, 255, 255, 0.9);
    max-width: 600px;
    margin-bottom: var(--spacing-md);
    opacity: 0;
    animation: fadeIn 0.8s ease 0.4s forwards;
}

@keyframes fadeIn {
    to {
        opacity: 1;
    }
}

/* ===================================
   Buttons
   =================================== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: 14px 32px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    opacity: 0;
    animation: fadeIn 0.8s ease 0.6s forwards;
}

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

.btn-primary:hover {
    background: var(--color-bg-alt);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-submit {
    background: var(--color-primary);
    color: var(--color-white);
    width: 100%;
    justify-content: center;
}

.btn-submit:hover {
    background: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn svg {
    transition: var(--transition);
}

.btn:hover svg {
    transform: translateX(4px);
}

/* ===================================
   Section
   =================================== */
section {
    padding: var(--spacing-xl) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.section-label {
    display: inline-block;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-primary);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: var(--spacing-sm);
}

.section-title {
    font-size: clamp(2rem, 4vw, 2.5rem);
    font-weight: 700;
    color: var(--color-secondary);
    letter-spacing: -0.02em;
    margin-bottom: var(--spacing-sm);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--color-text-light);
}

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

.about-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
    align-items: center;
}

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

.about-text p {
    font-size: 1.25rem;
    color: var(--color-text);
    line-height: 1.8;
}

.about-features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.feature-card {
    background: var(--color-bg-alt);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    text-align: center;
    transition: var(--transition);
}

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

.feature-icon {
    width: 64px;
    height: 64px;
    background: linear-gradient(135deg, var(--color-primary) 0%, #60a5fa 100%);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto var(--spacing-sm);
    color: var(--color-white);
}

.feature-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-secondary);
    margin-bottom: var(--spacing-xs);
}

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

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

.products-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-md);
}

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

.product-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.product-image {
    position: relative;
    aspect-ratio: 16/10;
    overflow: hidden;
}

.product-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

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

.product-overlay {
    position: absolute;
    top: var(--spacing-sm);
    left: var(--spacing-sm);
    background: rgba(15, 23, 42, 0.9);
    padding: 6px 12px;
    border-radius: var(--radius-sm);
}

.product-tag {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--color-white);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.product-content {
    padding: var(--spacing-md);
}

.product-content h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-secondary);
    margin-bottom: var(--spacing-xs);
}

.product-content p {
    color: var(--color-text-light);
    font-size: 0.95rem;
    line-height: 1.6;
}

/* ===================================
   Contact Section
   =================================== */
.contact {
    position: relative;
    background: var(--color-bg);
}

.contact-bg {
    position: absolute;
    top: 0;
    right: 0;
    width: 40%;
    height: 100%;
    background: url('../images/contact-bg.jpg') center/cover no-repeat;
    opacity: 0.1;
    display: none;
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
}

.contact-form-wrapper {
    background: var(--color-bg-alt);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 14px 16px;
    font-size: 1rem;
    background: var(--color-white);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    color: var(--color-text);
    transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

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

.contact-info-wrapper {
    display: flex;
    align-items: center;
}

.contact-info {
    width: 100%;
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
    border-radius: var(--radius-md);
    transition: var(--transition);
}

.contact-item:hover {
    background: var(--color-bg-alt);
}

.contact-icon {
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, var(--color-primary) 0%, #60a5fa 100%);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-white);
    flex-shrink: 0;
}

.contact-text h4 {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-text-light);
    margin-bottom: 4px;
}

.contact-text p {
    font-size: 1rem;
    color: var(--color-text);
}

/* ===================================
   Footer
   =================================== */
.footer {
    background: var(--color-secondary);
    color: var(--color-white);
    padding: var(--spacing-lg) 0 var(--spacing-md);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.footer-brand h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.footer-brand p {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.95rem;
}

.footer-links h4,
.footer-contact h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--color-white);
}

.footer-links ul {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.footer-links a {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.95rem;
}

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

.footer-contact p {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.95rem;
    margin-bottom: var(--spacing-xs);
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-bottom p {
    color: rgba(255, 255, 255, 0.5);
    font-size: 0.875rem;
}

/* ===================================
   Responsive Design
   =================================== */
@media (min-width: 768px) {
    .about-content {
        grid-template-columns: 1fr 1.5fr;
    }

    .about-text {
        text-align: left;
    }

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

    .contact-bg {
        display: block;
    }
}

@media (max-width: 768px) {
    .nav-links {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        flex-direction: column;
        background: var(--color-white);
        padding: var(--spacing-md);
        gap: var(--spacing-sm);
        border-bottom: 1px solid var(--color-border);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition);
    }

    .nav-links.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .menu-toggle {
        display: flex;
    }

    .menu-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 6px);
    }

    .menu-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .menu-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -6px);
    }

    section {
        padding: var(--spacing-lg) 0;
    }

    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

/* ===================================
   Scroll Animations
   =================================== */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

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