/* ========================================
   内蒙古利宸乳业 - 品牌官网样式
   ======================================== */

/* CSS 变量 */
:root {
    --color-primary: #2D5A3D;
    --color-primary-dark: #1E3D2A;
    --color-primary-light: #3D7A52;
    --color-accent: #C9A96E;
    --color-accent-dark: #B08D4F;
    --color-accent-light: #D9C99E;
    --color-white: #FAFAFA;
    --color-cream: #F5F0E8;
    --color-brown: #3E2723;
    --color-brown-light: #5D4037;
    --color-text: #333333;
    --color-text-light: #666666;
    --color-text-muted: #999999;
    --font-serif: 'Noto Serif SC', 'Source Han Serif SC', 'SimSun', serif;
    --font-sans: 'Noto Sans SC', 'Source Han Sans SC', 'Microsoft YaHei', sans-serif;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 20px rgba(0,0,0,0.12);
    --shadow-lg: 0 8px 40px rgba(0,0,0,0.16);
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 重置 */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

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

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

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

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

/* ========================================
   导航栏
   ======================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 16px 0;
    transition: var(--transition);
}

.navbar.scrolled {
    background: rgba(30, 61, 42, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-md);
    padding: 12px 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: 8px;
    font-family: var(--font-serif);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-white);
    transition: var(--transition);
}

.navbar.scrolled .nav-logo {
    color: var(--color-white);
}

.logo-icon {
    color: var(--color-accent);
    font-size: 1.5rem;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav-link {
    font-size: 0.9375rem;
    font-weight: 500;
    color: rgba(255,255,255,0.9);
    position: relative;
    transition: var(--transition);
}

.navbar.scrolled .nav-link {
    color: rgba(255,255,255,0.9);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--color-accent);
    transition: var(--transition);
}

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

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

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--color-white);
    transition: var(--transition);
}

.navbar.scrolled .nav-toggle span {
    background: var(--color-white);
}

/* ========================================
   Hero 首屏
   ======================================== */
.hero {
    position: relative;
    height: 100vh;
    min-height: 600px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, #1a3a2a 0%, #2d5a3d 40%, #3d7a52 100%);
}

.hero-bg::before {
    content: '';
    position: absolute;
    inset: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><circle cx="20" cy="30" r="1" fill="rgba(255,255,255,0.1)"/><circle cx="80" cy="20" r="1.5" fill="rgba(255,255,255,0.08)"/><circle cx="50" cy="60" r="1" fill="rgba(255,255,255,0.06)"/><circle cx="30" cy="80" r="1.2" fill="rgba(255,255,255,0.1)"/><circle cx="70" cy="70" r="0.8" fill="rgba(255,255,255,0.07)"/></svg>');
    background-size: 200px 200px;
    animation: float 20s linear infinite;
}

@keyframes float {
    0% { transform: translateY(0); }
    100% { transform: translateY(-200px); }
}

.hero-overlay {
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at center, transparent 0%, rgba(0,0,0,0.3) 100%);
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    color: var(--color-white);
    padding: 0 24px;
}

.hero-title {
    font-family: var(--font-serif);
    font-size: clamp(2.5rem, 6vw, 4.5rem);
    font-weight: 900;
    line-height: 1.2;
    margin-bottom: 16px;
}

.hero-line {
    display: block;
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 0.8s ease forwards;
}

.hero-line:nth-child(1) { animation-delay: 0.2s; }
.hero-line:nth-child(2) { animation-delay: 0.4s; }

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

.hero-subtitle {
    font-family: var(--font-serif);
    font-size: clamp(1.125rem, 2.5vw, 1.5rem);
    font-weight: 400;
    letter-spacing: 0.3em;
    color: var(--color-accent-light);
    margin-bottom: 12px;
    opacity: 0;
    animation: fadeInUp 0.8s ease 0.6s forwards;
}

.hero-desc {
    font-size: clamp(0.9375rem, 2vw, 1.125rem);
    color: rgba(255,255,255,0.8);
    margin-bottom: 32px;
    opacity: 0;
    animation: fadeInUp 0.8s ease 0.8s forwards;
}

.hero-cta {
    display: inline-block;
    padding: 14px 40px;
    background: var(--color-accent);
    color: var(--color-brown);
    font-weight: 600;
    font-size: 1rem;
    border-radius: var(--radius-sm);
    transition: var(--transition);
    opacity: 0;
    animation: fadeInUp 0.8s ease 1s forwards;
}

.hero-cta:hover {
    background: var(--color-accent-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.scroll-down {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 2;
    width: 32px;
    height: 50px;
    border: 2px solid rgba(255,255,255,0.5);
    border-radius: 16px;
    display: flex;
    justify-content: center;
    padding-top: 8px;
    transition: var(--transition);
}

.scroll-down:hover {
    border-color: var(--color-accent);
}

.scroll-down span {
    display: block;
    width: 6px;
    height: 10px;
    background: var(--color-accent);
    border-radius: 3px;
    animation: scrollBounce 2s ease infinite;
}

@keyframes scrollBounce {
    0%, 100% { transform: translateY(0); opacity: 1; }
    50% { transform: translateY(12px); opacity: 0.3; }
}

/* ========================================
   通用区块
   ======================================== */
.section {
    padding: 100px 0;
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-tag {
    display: inline-block;
    padding: 6px 20px;
    background: rgba(201, 169, 110, 0.15);
    color: var(--color-accent-dark);
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: 20px;
    margin-bottom: 16px;
    letter-spacing: 0.1em;
}

.section-title {
    font-family: var(--font-serif);
    font-size: clamp(1.75rem, 4vw, 2.5rem);
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1.3;
}

/* 滚动动画 */
.reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: all 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

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

/* ========================================
   企业概况
   ======================================== */
.about {
    background: var(--color-white);
}

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

.about-text {
    margin-bottom: 40px;
}

.about-text p {
    margin-bottom: 16px;
    color: var(--color-text-light);
    font-size: 1rem;
}

.about-text .lead {
    font-size: 1.125rem;
    color: var(--color-text);
    line-height: 1.8;
}

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

.highlight {
    color: var(--color-accent-dark);
    font-weight: 700;
}

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

.stat-item {
    text-align: center;
    padding: 24px;
    background: var(--color-cream);
    border-radius: var(--radius-md);
    transition: var(--transition);
}

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

.stat-number {
    display: block;
    font-family: var(--font-serif);
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--color-accent-dark);
    margin-bottom: 4px;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--color-text-muted);
}

.about-visual {
    position: relative;
}

.about-image-wrapper {
    position: relative;
    height: 480px;
}

.about-image {
    position: absolute;
    border-radius: var(--radius-lg);
    background-size: cover;
    background-position: center;
}

.about-image-main {
    width: 85%;
    height: 100%;
    top: 0;
    left: 0;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

.about-image-main img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 0;
}

.about-image-accent {
    width: 50%;
    height: 50%;
    bottom: -20px;
    right: 0;
    background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-dark) 100%);
    border: 4px solid var(--color-white);
    box-shadow: var(--shadow-md);
    overflow: hidden;
}

.about-image-accent img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 0;
}

/* ========================================
   全产业链
   ======================================== */
.chain {
    background: linear-gradient(180deg, var(--color-cream) 0%, var(--color-white) 100%);
}

.chain-timeline {
    display: flex;
    align-items: stretch;
    justify-content: center;
    gap: 0;
}

.chain-card {
    flex: 1;
    max-width: 360px;
    background: var(--color-white);
    border-radius: var(--radius-lg);
    padding: 40px 32px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    position: relative;
}

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

.chain-icon {
    width: 64px;
    height: 64px;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-white);
    margin-bottom: 20px;
}

.chain-icon svg {
    width: 32px;
    height: 32px;
}

.chain-number {
    font-family: var(--font-serif);
    font-size: 0.875rem;
    font-weight: 700;
    color: var(--color-accent);
    margin-bottom: 8px;
}

.chain-title {
    font-family: var(--font-serif);
    font-size: 1.375rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: 4px;
}

.chain-subtitle {
    font-size: 0.9375rem;
    color: var(--color-accent-dark);
    font-weight: 500;
    margin-bottom: 20px;
}

.chain-list {
    list-style: none;
}

.chain-list li {
    position: relative;
    padding-left: 20px;
    margin-bottom: 10px;
    font-size: 0.9375rem;
    color: var(--color-text-light);
    line-height: 1.6;
}

.chain-list li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 10px;
    width: 6px;
    height: 6px;
    background: var(--color-accent);
    border-radius: 50%;
}

.chain-connector {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 0 16px;
    min-width: 60px;
}

.connector-line {
    display: block;
    width: 40px;
    height: 2px;
    background: linear-gradient(90deg, var(--color-accent-light), var(--color-accent));
}

.connector-arrow {
    color: var(--color-accent);
    font-size: 1rem;
    margin-top: 4px;
}

/* ========================================
   核心优势
   ======================================== */
.advantages {
    background: var(--color-white);
}

.advantages-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.advantage-card {
    background: var(--color-white);
    border: 1px solid rgba(0,0,0,0.06);
    border-radius: var(--radius-lg);
    padding: 40px 32px;
    text-align: center;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.advantage-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
    transform: scaleX(0);
    transition: var(--transition);
}

.advantage-card:hover::before {
    transform: scaleX(1);
}

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

.advantage-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, rgba(45, 90, 61, 0.1) 0%, rgba(45, 90, 61, 0.05) 100%);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    color: var(--color-primary);
    transition: var(--transition);
}

.advantage-card:hover .advantage-icon {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    color: var(--color-white);
}

.advantage-icon svg {
    width: 28px;
    height: 28px;
}

.advantage-card h3 {
    font-family: var(--font-serif);
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: 12px;
}

.advantage-card p {
    font-size: 0.9375rem;
    color: var(--color-text-light);
    line-height: 1.7;
}

/* ========================================
   产品展示
   ======================================== */
.product {
    background: linear-gradient(180deg, var(--color-white) 0%, var(--color-cream) 100%);
}

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

.product-image-wrapper {
    position: relative;
}

.product-image {
    background: var(--color-white);
    border-radius: var(--radius-lg);
    padding: 40px;
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    justify-content: center;
}

.product-image img {
    max-height: 400px;
    object-fit: contain;
    border-radius: var(--radius-sm);
}

.product-badge {
    position: absolute;
    top: -12px;
    right: 20px;
    background: linear-gradient(135deg, var(--color-accent) 0%, var(--color-accent-dark) 100%);
    color: var(--color-white);
    font-size: 0.875rem;
    font-weight: 600;
    padding: 8px 20px;
    border-radius: 20px;
    box-shadow: var(--shadow-md);
}

.product-details {
    padding: 20px 0;
}

.product-name {
    font-family: var(--font-serif);
    font-size: clamp(1.5rem, 3vw, 2rem);
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: 8px;
}

.product-category {
    font-size: 1rem;
    color: var(--color-accent-dark);
    font-weight: 500;
    margin-bottom: 24px;
}

.product-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 32px;
}

.tag {
    display: inline-block;
    padding: 6px 16px;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
}

.tag-primary {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    color: var(--color-white);
}

.tag-secondary {
    background: rgba(201, 169, 110, 0.15);
    color: var(--color-accent-dark);
}

.product-features {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.feature-item {
    display: flex;
    align-items: flex-start;
    gap: 16px;
}

.feature-icon {
    width: 28px;
    height: 28px;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
    color: var(--color-white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.875rem;
    flex-shrink: 0;
    margin-top: 2px;
}

.feature-text {
    display: flex;
    flex-direction: column;
}

.feature-text strong {
    font-size: 1rem;
    color: var(--color-primary);
    margin-bottom: 4px;
}

.feature-text span {
    font-size: 0.9375rem;
    color: var(--color-text-light);
    line-height: 1.6;
}

/* ========================================
   页脚
   ======================================== */
.footer {
    background: linear-gradient(135deg, var(--color-primary-dark) 0%, var(--color-brown) 100%);
    color: var(--color-white);
    padding: 60px 0 24px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-brand h3 {
    font-family: var(--font-serif);
    font-size: 1.375rem;
    font-weight: 700;
    margin-bottom: 12px;
}

.footer-brand p {
    color: rgba(255,255,255,0.7);
    font-size: 0.9375rem;
    margin-bottom: 4px;
}

.footer-info h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--color-accent-light);
}

.footer-info p {
    color: rgba(255,255,255,0.7);
    font-size: 0.9375rem;
    margin-bottom: 6px;
}

.footer-bottom {
    border-top: 1px solid rgba(255,255,255,0.1);
    padding-top: 24px;
    text-align: center;
}

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

.footer-tech {
    margin-top: 8px;
    font-size: 0.8125rem;
}

.footer-tech a {
    color: var(--color-accent-light);
    transition: var(--transition);
}

.footer-tech a:hover {
    color: var(--color-accent);
    text-decoration: underline;
}

/* ========================================
   响应式设计
   ======================================== */
@media (max-width: 991px) {
    .about-grid {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .about-visual {
        order: -1;
    }

    .about-image-wrapper {
        height: 320px;
    }

    .chain-timeline {
        flex-direction: column;
        align-items: center;
        gap: 24px;
    }

    .chain-card {
        max-width: 100%;
        width: 100%;
    }

    .chain-connector {
        transform: rotate(90deg);
        padding: 8px 0;
    }

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

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

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

@media (max-width: 767px) {
    .nav-toggle {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 300px;
        height: 100vh;
        background: var(--color-white);
        flex-direction: column;
        padding: 80px 32px 32px;
        gap: 24px;
        transition: var(--transition);
        box-shadow: var(--shadow-lg);
    }

    .nav-menu.active {
        right: 0;
    }

    .nav-link {
        color: var(--color-text);
        font-size: 1.125rem;
    }

    .section {
        padding: 60px 0;
    }

    .about-stats {
        grid-template-columns: 1fr;
    }

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

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

    .product-image {
        padding: 24px;
    }
}

/* ========================================
   辅助类
   ======================================== */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}