/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--text-primary);
    background-color: var(--secondary-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* CSS Variables - Enhanced Design System */
:root {
    /* Colors - 品牌规范 */
    --primary-color: #E53935;
    --primary-hover: #C62828;
    --primary-light: #FFCDD2;
    --secondary-color: #f8fafc;
    --text-primary: #333333;
    --text-secondary: #666666;
    --text-light: #999999;
    --text-white: #ffffff;
    --accent-color: #f59e0b;
    --accent-hover: #d97706;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    --border-color: #e2e8f0;
    --border-light: #f1f5f9;

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #E53935 0%, #C62828 100%);
    --gradient-secondary: linear-gradient(135deg, #FF5252 0%, #E53935 100%);
    --gradient-hero: linear-gradient(180deg, rgba(0,0,0,0.1) 0%, rgba(0,0,0,0.4) 100%);

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.2);
    --shadow-glow: 0 0 20px rgba(229, 57, 53, 0.3);
    --shadow-nav: 0 1px 8px rgba(0, 0, 0, 0.05);

    /* Spacing System */
    --spacing-xs: 0.25rem;    /* 4px */
    --spacing-sm: 0.5rem;     /* 8px */
    --spacing-md: 1rem;       /* 16px */
    --spacing-lg: 1.5rem;     /* 24px */
    --spacing-xl: 2rem;       /* 32px */
    --spacing-2xl: 3rem;      /* 48px */
    --spacing-3xl: 4rem;      /* 64px */

    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Microsoft YaHei", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    --font-size-xs: 0.75rem;   /* 12px - 辅助文字 */
    --font-size-sm: 0.875rem;  /* 14px - 正文 */
    --font-size-base: 1rem;    /* 16px - 副标题 */
    --font-size-lg: 1.125rem;  /* 18px - 副标题 */
    --font-size-xl: 1.25rem;   /* 20px */
    --font-size-2xl: 1.75rem;  /* 28px - 大标题 */
    --font-size-3xl: 2.25rem;  /* 36px */
    --font-size-4xl: 2.5rem;   /* 40px */
    --font-size-5xl: 3rem;     /* 48px */
    --line-height-tight: 1.25;
    --line-height-normal: 1.5;
    --line-height-relaxed: 1.75;

    /* Border Radius */
    --radius-sm: 0.25rem;      /* 4px */
    --radius: 0.5rem;          /* 8px */
    --radius-md: 0.75rem;      /* 12px */
    --radius-lg: 1rem;         /* 16px */
    --radius-xl: 1.5rem;       /* 24px */
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition: 0.3s ease;
    --transition-slow: 0.5s ease;
    --transition-all: all 0.3s ease;
    --transition-transform: transform 0.3s ease;
    --transition-opacity: opacity 0.3s ease;

    /* Z-index */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal-backdrop: 1040;
    --z-modal: 1050;
    --z-popover: 1060;
    --z-tooltip: 1070;
}

/* Navigation */
.navbar {
    background-color: #fff;
    box-shadow: var(--shadow-nav);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: var(--transition);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
    padding: 0 20px;
}

.navbar .logo img {
    height: 50px;
    transition: var(--transition);
}

.navbar .logo:hover img {
    transform: scale(1.05);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 30px;
    padding: 0 20px;
}

.nav-menu li {
    position: relative;
}

.nav-menu a {
    display: flex;
    align-items: center;
    justify-content: center;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    font-size: var(--font-size-base);
    position: relative;
    transition: var(--transition);
    padding: 8px 20px;
    border-radius: 25px;
    min-width: 80px;
}

/* 椭圆背景 - 仅在hover和active时显示 */
.nav-menu a:hover {
    background-color: rgba(229, 57, 53, 0.1);
}

.nav-menu a.active {
    color: var(--primary-color);
    font-weight: 700;
    background-color: rgba(229, 57, 53, 0.1);
}

/* 下划线效果 */
.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: var(--transition);
}

.nav-menu a:hover::after,
.nav-menu a.active::after {
    width: 60%;
}

.mobile-menu-toggle {
    display: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-primary);
}

/* Main Content */
main {
    margin-top: 70px;
    min-height: calc(100vh - 70px - 300px);
}

/* Sections */
section {
    padding: 80px 0;
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.section-subtitle {
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
}

/* Buttons - Enhanced System */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md) var(--spacing-xl);
    text-decoration: none;
    border-radius: var(--radius-md);
    font-weight: 500;
    font-size: var(--font-size-base);
    line-height: var(--line-height-tight);
    transition: var(--transition-all);
    cursor: pointer;
    border: none;
    white-space: nowrap;
    position: relative;
    overflow: hidden;
}

.btn:focus {
    outline: 2px solid var(--primary-light);
    outline-offset: 2px;
}

.btn-primary {
    background-color: var(--primary-color);
    color: #fff;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: rgba(0, 0, 0, 0.15) 0 4px 20px;
}

.btn-primary:active {
    transform: translateY(0);
    box-shadow: var(--shadow-sm);
}

.btn-outline {
    background-color: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-outline:hover {
    background-color: var(--primary-color);
    color: #fff;
    transform: translateY(-2px);
    box-shadow: rgba(0, 0, 0, 0.15) 0 4px 20px;
}

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

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

.btn-accent {
    background-color: var(--accent-color);
    color: #fff;
}

.btn-accent:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: rgba(0, 0, 0, 0.15) 0 4px 20px;
}

/* 统一按钮样式 - 查看更多、立即咨询等 */
.btn-more,
.btn-consult,
.btn-contact {
    display: inline-block;
    padding: var(--spacing-md) var(--spacing-2xl);
    background-color: var(--primary-color);
    color: #fff;
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: var(--transition-all);
    font-weight: 500;
    font-size: var(--font-size-base);
    box-shadow: var(--shadow-sm);
    border: none;
    cursor: pointer;
}

.btn-more:hover,
.btn-consult:hover,
.btn-contact:hover {
    background-color: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: rgba(0, 0, 0, 0.15) 0 4px 20px;
}

/* Button Sizes */
.btn-sm {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
}

.btn-lg {
    padding: var(--spacing-lg) var(--spacing-2xl);
    font-size: var(--font-size-lg);
}

/* Footer */
.footer {
    background-color: #2c3e50;
    color: #ecf0f1;
    padding: 60px 0 20px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    margin-bottom: 1rem;
    color: #fff;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: #bdc3c7;
    text-decoration: none;
    transition: var(--transition);
}

.footer-section a:hover {
    color: #fff;
}

.footer-section p {
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #34495e;
}

/* Back to Top */
.back-to-top {
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 48px;
    height: 48px;
    background-color: var(--primary-color);
    color: #fff;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
    box-shadow: rgba(0, 0, 0, 0.1) 0 4px 12px;
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background-color: var(--primary-hover);
    transform: translateY(-3px);
    box-shadow: rgba(0, 0, 0, 0.15) 0 6px 20px;
}

/* Text Utilities */
.text-center {
    text-align: center;
}

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

.text-right {
    text-align: right;
}

/* Loading */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }

    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background-color: #fff;
        flex-direction: column;
        justify-content: flex-start;
        align-items: center;
        padding-top: 2rem;
        transition: var(--transition);
        box-shadow: var(--shadow);
    }

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

    .mobile-menu-toggle {
        display: block;
    }

    section {
        padding: 60px 0;
    }

    .section-title {
        font-size: 2rem;
    }

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

    .back-to-top {
        width: 40px;
        height: 40px;
        bottom: 20px;
        right: 20px;
    }
}

@media (max-width: 480px) {
    .navbar .logo img {
        height: 40px;
    }

    .navbar .container {
        height: 60px;
    }

    main {
        margin-top: 60px;
    }

    .nav-menu {
        top: 60px;
        height: calc(100vh - 60px);
    }

    .btn {
        padding: 10px 20px;
        font-size: 0.9rem;
    }

    .section-title {
        font-size: 1.8rem;
    }
}

/* Animation Classes */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.5s ease, transform 0.5s ease;
}

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

/* Enhanced Animation Classes */
.slide-up {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.slide-up.visible {
    opacity: 1;
    transform: translateY(0);
}

.slide-in-left {
    opacity: 0;
    transform: translateX(-30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.slide-in-left.visible {
    opacity: 1;
    transform: translateX(0);
}

.slide-in-right {
    opacity: 0;
    transform: translateX(30px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.slide-in-right.visible {
    opacity: 1;
    transform: translateX(0);
}

.scale-in {
    opacity: 0;
    transform: scale(0.9);
    transition: opacity 0.5s ease-out, transform 0.5s ease-out;
}

.scale-in.visible {
    opacity: 1;
    transform: scale(1);
}

/* Grid System */
.grid {
    display: grid;
    gap: 2rem;
}

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

.grid-3 {
    grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
    grid-template-columns: repeat(4, 1fr);
}

@media (max-width: 1024px) {
    .grid-4 {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 768px) {
    .grid-3,
    .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 480px) {
    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }
}

/* Utility Classes */
.text-gradient {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.glass-effect {
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.card-hover {
    transition: var(--transition-transform);
}

.card-hover:hover {
    transform: translateY(-5px);
}

/* Focus States */
.focus-ring {
    transition: var(--transition-fast);
}

.focus-ring:focus {
    outline: none;
    box-shadow: 0 0 0 3px var(--primary-light);
}

/* Spacing Utilities */
.p-sm { padding: var(--spacing-sm); }
.p-md { padding: var(--spacing-md); }
.p-lg { padding: var(--spacing-lg); }
.p-xl { padding: var(--spacing-xl); }

.m-sm { margin: var(--spacing-sm); }
.m-md { margin: var(--spacing-md); }
.m-lg { margin: var(--spacing-lg); }
.m-xl { margin: var(--spacing-xl); }

/* Text Utilities */
.text-xs { font-size: var(--font-size-xs); }
.text-sm { font-size: var(--font-size-sm); }
.text-lg { font-size: var(--font-size-lg); }
.text-xl { font-size: var(--font-size-xl); }
.text-2xl { font-size: var(--font-size-2xl); }
.text-3xl { font-size: var(--font-size-3xl); }

.font-light { font-weight: 300; }
.font-normal { font-weight: 400; }
.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }
.font-bold { font-weight: 700; }