/* ========== 全局样式 ========== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --color-black: #000000;
    --color-white: #ffffff;
    --color-gray-50: #f5f5f7;
    --color-gray-100: #e8e8ed;
    --color-gray-200: #d2d2d7;
    --color-gray-300: #86868b;
    --color-gray-400: #6e6e73;
    --color-gray-500: #1d1d1f;
    --color-blue: #0071e3;
    --color-blue-hover: #0077ed;
    --font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-fast: all 0.2s ease;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: 17px;
    line-height: 1.47059;
    font-weight: 400;
    letter-spacing: -0.022em;
    color: var(--color-gray-500);
    background-color: var(--color-white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

ul {
    list-style: none;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 22px;
}

/* ========== 导航栏 ========== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    transition: var(--transition-smooth);
}

.nav-container {
    max-width: 1000px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 22px;
    height: 44px;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--color-white);
    font-size: 18px;
    font-weight: 600;
}

.nav-logo svg {
    fill: var(--color-white);
}

.nav-menu {
    display: flex;
    gap: 36px;
}

.nav-menu a {
    color: var(--color-gray-300);
    font-size: 12px;
    font-weight: 400;
    opacity: 0.8;
    transition: var(--transition-fast);
}

.nav-menu a:hover {
    opacity: 1;
    color: var(--color-white);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    width: 18px;
    height: 1px;
    background-color: var(--color-white);
    transition: var(--transition-fast);
}

/* ========== Hero区域 ========== */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 120px 22px 80px;
    background: var(--color-black);
    color: var(--color-white);
    position: relative;
    overflow: hidden;
}

.hero-content {
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 1s ease forwards;
}

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

.hero-title {
    font-size: clamp(40px, 8vw, 80px);
    font-weight: 700;
    line-height: 1.05;
    letter-spacing: -0.015em;
    margin-bottom: 16px;
}

.hero-subtitle {
    font-size: clamp(20px, 4vw, 28px);
    font-weight: 400;
    line-height: 1.2;
    color: var(--color-gray-300);
    margin-bottom: 32px;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    display: inline-block;
    padding: 12px 26px;
    font-size: 17px;
    font-weight: 400;
    border-radius: 980px;
    transition: var(--transition-fast);
    cursor: pointer;
    border: none;
}

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

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

.btn-secondary {
    background-color: transparent;
    color: var(--color-blue);
    border: 1px solid var(--color-blue);
}

.btn-secondary:hover {
    background-color: var(--color-blue);
    color: var(--color-white);
}

.hero-visual {
    margin-top: 60px;
    width: 100%;
    max-width: 900px;
}

.hero-image {
    width: 100%;
    height: 400px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 20px;
    box-shadow: 0 40px 80px rgba(0, 0, 0, 0.4);
}

/* ========== 产品展示 ========== */
.products {
    padding: 80px 0;
    background-color: var(--color-white);
}

.section-title {
    font-size: clamp(32px, 5vw, 56px);
    font-weight: 700;
    line-height: 1.08;
    letter-spacing: -0.005em;
    text-align: center;
    margin-bottom: 60px;
    color: var(--color-gray-500);
}

.products-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
    max-width: 1000px;
    margin: 0 auto;
}

.product-card {
    background: var(--color-gray-50);
    border-radius: 18px;
    padding: 40px 30px;
    text-align: center;
    transition: var(--transition-smooth);
    opacity: 0;
    transform: translateY(20px);
}

.product-card.visible {
    opacity: 1;
    transform: translateY(0);
}

.product-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
}

.product-image {
    margin-bottom: 24px;
}

.product-placeholder {
    width: 100%;
    height: 200px;
    border-radius: 12px;
    margin: 0 auto;
}

.product-1 {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
}

.product-2 {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
}

.product-3 {
    background: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);
}

.product-name {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--color-gray-500);
}

.product-desc {
    font-size: 17px;
    color: var(--color-gray-400);
    margin-bottom: 16px;
}

.product-link {
    font-size: 17px;
    color: var(--color-blue);
    font-weight: 500;
}

.product-link:hover {
    text-decoration: underline;
}

/* ========== 特性展示 ========== */
.features {
    padding: 100px 0;
    background-color: var(--color-gray-50);
}

.features-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 40px;
    max-width: 1000px;
    margin: 0 auto;
}

.feature-item {
    text-align: center;
    opacity: 0;
    transform: translateY(20px);
    transition: var(--transition-smooth);
}

.feature-item.visible {
    opacity: 1;
    transform: translateY(0);
}

.feature-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 80px;
    height: 80px;
    margin-bottom: 20px;
    color: var(--color-blue);
}

.feature-icon svg {
    width: 100%;
    height: 100%;
}

.feature-title {
    font-size: 21px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--color-gray-500);
}

.feature-desc {
    font-size: 17px;
    color: var(--color-gray-400);
    line-height: 1.5;
}

/* ========== 大型宣传区域 ========== */
.promo {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 100px 22px;
    background: var(--color-black);
    color: var(--color-white);
    text-align: center;
    min-height: 600px;
}

.promo-title {
    font-size: clamp(40px, 7vw, 64px);
    font-weight: 700;
    line-height: 1.05;
    margin-bottom: 16px;
}

.promo-subtitle {
    font-size: clamp(20px, 4vw, 28px);
    font-weight: 400;
    color: var(--color-gray-300);
    margin-bottom: 32px;
}

.promo-visual {
    margin-top: 60px;
    width: 100%;
    max-width: 800px;
}

.promo-placeholder {
    width: 100%;
    height: 350px;
    background: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
    border-radius: 20px;
    box-shadow: 0 40px 80px rgba(0, 0, 0, 0.3);
}

/* ========== 关于我们 ========== */
.about {
    padding: 100px 0;
    background-color: var(--color-white);
}

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

.about-text {
    font-size: 21px;
    line-height: 1.5;
    color: var(--color-gray-500);
    margin-bottom: 60px;
}

.about-stats {
    display: flex;
    justify-content: center;
    gap: 80px;
    flex-wrap: wrap;
}

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

.stat-number {
    font-size: 48px;
    font-weight: 700;
    color: var(--color-gray-500);
    margin-bottom: 8px;
}

.stat-label {
    font-size: 17px;
    color: var(--color-gray-400);
}

/* ========== 页脚 ========== */
.footer {
    background-color: var(--color-gray-50);
    padding: 60px 0 30px;
    border-top: 1px solid var(--color-gray-100);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-title {
    font-size: 12px;
    font-weight: 600;
    color: var(--color-gray-500);
    margin-bottom: 16px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.footer-links li {
    margin-bottom: 10px;
}

.footer-links a {
    font-size: 12px;
    color: var(--color-gray-400);
}

.footer-links a:hover {
    color: var(--color-gray-500);
    text-decoration: underline;
}

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 30px;
    border-top: 1px solid var(--color-gray-100);
    flex-wrap: wrap;
    gap: 16px;
}

.footer-bottom p {
    font-size: 12px;
    color: var(--color-gray-400);
}

.footer-legal {
    display: flex;
    gap: 20px;
}

.footer-legal a {
    font-size: 12px;
    color: var(--color-gray-400);
}

.footer-legal a:hover {
    color: var(--color-gray-500);
    text-decoration: underline;
}

.footer-beian {
    display: flex;
    gap: 20px;
}

.footer-beian a {
    font-size: 12px;
    color: var(--color-gray-400);
}

.footer-beian a:hover {
    color: var(--color-gray-500);
    text-decoration: underline;
}

/* ========== 响应式设计 ========== */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 44px;
        left: 0;
        right: 0;
        background: rgba(0, 0, 0, 0.95);
        backdrop-filter: saturate(180%) blur(20px);
        -webkit-backdrop-filter: saturate(180%) blur(20px);
        flex-direction: column;
        gap: 0;
        padding: 20px 0;
        transform: translateY(-100%);
        opacity: 0;
        transition: var(--transition-smooth);
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
    }

    .nav-menu li {
        width: 100%;
    }

    .nav-menu a {
        display: block;
        padding: 16px 22px;
        font-size: 17px;
        text-align: center;
    }

    .nav-toggle {
        display: flex;
    }

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

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

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

    .hero {
        padding: 100px 22px 60px;
    }

    .hero-image {
        height: 250px;
    }

    .products,
    .features {
        padding: 60px 0;
    }

    .products-grid {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .features-list {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .about-stats {
        gap: 40px;
    }

    .stat-number {
        font-size: 36px;
    }

    .promo {
        padding: 60px 22px;
    }

    .promo-placeholder {
        height: 250px;
    }

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

    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .footer-content {
        grid-template-columns: 1fr;
    }

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

    .btn {
        width: 100%;
    }
}

/* ========== 滚动动画延迟 ========== */
.product-card:nth-child(1) { transition-delay: 0.1s; }
.product-card:nth-child(2) { transition-delay: 0.2s; }
.product-card:nth-child(3) { transition-delay: 0.3s; }

.feature-item:nth-child(1) { transition-delay: 0.1s; }
.feature-item:nth-child(2) { transition-delay: 0.2s; }
.feature-item:nth-child(3) { transition-delay: 0.3s; }
.feature-item:nth-child(4) { transition-delay: 0.4s; }