/* ============================================
   UI设计系统 - 全屏滚动分节布局
   包含毛玻璃效果、渐变设计、微交互动效
   ============================================ */

/* ==================== CSS变量 ==================== */
:root {
    /* 颜色系统 */
    --color-primary: #1a1a2e;
    --color-secondary: #16213e;
    --color-accent-start: #667eea;
    --color-accent-end: #764ba2;
    --color-accent: linear-gradient(135deg, var(--color-accent-start), var(--color-accent-end));
    --color-bg-dark: #0f0f1a;
    --color-bg-light: #f8f9fc;
    --color-text-primary: #ffffff;
    --color-text-secondary: #a0a0b8;
    --color-text-muted: #6b6b80;
    --color-glass: rgba(255, 255, 255, 0.08);
    --color-glass-border: rgba(255, 255, 255, 0.15);
    --color-glass-hover: rgba(255, 255, 255, 0.12);
    
    /* 间距系统 */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 1.5rem;
    --space-lg: 2rem;
    --space-xl: 3rem;
    --space-2xl: 5rem;
    
    /* 圆角系统 */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 28px;
    --radius-full: 9999px;
    
    /* 阴影系统 */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.15);
    --shadow-md: 0 8px 32px rgba(0, 0, 0, 0.25);
    --shadow-lg: 0 20px 60px rgba(0, 0, 0, 0.35);
    --shadow-glow: 0 0 40px rgba(102, 126, 234, 0.3);
    
    /* 过渡 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* 字体 */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-display: 'Poppins', var(--font-primary);
}

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

html {
    scroll-behavior: smooth;
    scrollbar-width: thin;
    scrollbar-color: var(--color-accent-start) var(--color-bg-dark);
}

html::-webkit-scrollbar {
    width: 8px;
}

html::-webkit-scrollbar-track {
    background: var(--color-bg-dark);
}

html::-webkit-scrollbar-thumb {
    background: linear-gradient(180deg, var(--color-accent-start), var(--color-accent-end));
    border-radius: var(--radius-full);
}

body {
    font-family: var(--font-primary);
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text-primary);
    background: var(--color-bg-dark);
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

ul, ol {
    list-style: none;
}

/* ==================== 排版 ==================== */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-display);
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: -0.02em;
}

h1 {
    font-size: clamp(2.5rem, 8vw, 5rem);
    background: var(--color-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

h2 {
    font-size: clamp(2rem, 5vw, 3.5rem);
}

h3 {
    font-size: clamp(1.5rem, 3vw, 2rem);
}

h4 {
    font-size: clamp(1.25rem, 2vw, 1.5rem);
}

p {
    color: var(--color-text-secondary);
    max-width: 65ch;
}

/* ==================== 容器 ==================== */
.container {
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

.container--narrow {
    max-width: 900px;
}

.container--wide {
    max-width: 1600px;
}

/* ==================== 全屏分节布局 ==================== */
.section {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    padding: var(--space-2xl) 0;
    overflow: hidden;
}

.section--hero {
    background: var(--color-bg-dark);
}

.section--alt {
    background: var(--color-primary);
}

.section--gradient {
    background: linear-gradient(180deg, var(--color-bg-dark) 0%, var(--color-secondary) 100%);
}

.section__content {
    position: relative;
    z-index: 2;
    width: 100%;
}

/* 分节装饰背景 */
.section__bg-pattern {
    position: absolute;
    inset: 0;
    opacity: 0.05;
    background-image: 
        radial-gradient(circle at 20% 50%, var(--color-accent-start) 0%, transparent 50%),
        radial-gradient(circle at 80% 50%, var(--color-accent-end) 0%, transparent 50%);
    pointer-events: none;
}

/* 几何装饰元素 */
.geo-decoration {
    position: absolute;
    pointer-events: none;
    opacity: 0.1;
}

.geo-decoration--circle {
    width: 400px;
    height: 400px;
    border: 2px solid var(--color-accent-start);
    border-radius: 50%;
}

.geo-decoration--square {
    width: 200px;
    height: 200px;
    border: 2px solid var(--color-accent-end);
    transform: rotate(45deg);
}

.geo-decoration--1 {
    top: 10%;
    right: 5%;
}

.geo-decoration--2 {
    bottom: 15%;
    left: 8%;
}

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

.navbar--scrolled {
    background: rgba(15, 15, 26, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-glass-border);
}

.navbar__container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.navbar__logo {
    font-family: var(--font-display);
    font-size: 1.75rem;
    font-weight: 800;
    background: var(--color-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.navbar__menu {
    display: flex;
    gap: var(--space-lg);
}

.navbar__link {
    position: relative;
    padding: var(--space-xs) 0;
    font-weight: 500;
    color: var(--color-text-secondary);
    transition: color var(--transition-fast);
}

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

.navbar__link:hover {
    color: var(--color-text-primary);
}

.navbar__link:hover::after {
    width: 100%;
}

.navbar__toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: var(--space-xs);
}

.navbar__toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--color-text-primary);
    transition: all var(--transition-fast);
}

/* 响应式导航 */
@media (max-width: 768px) {
    .navbar__menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 300px;
        height: 100vh;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: var(--space-xl);
        background: var(--color-primary);
        backdrop-filter: blur(30px);
        -webkit-backdrop-filter: blur(30px);
        transition: right var(--transition-normal);
    }
    
    .navbar__menu.active {
        right: 0;
    }
    
    .navbar__toggle {
        display: flex;
        z-index: 1001;
    }
    
    .navbar__toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .navbar__toggle.active span:nth-child(2) {
        opacity: 0;
    }
    
    .navbar__toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }
}

/* ==================== 卡片组件 ==================== */
.card {
    background: var(--color-glass);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    inset: 0;
    background: var(--color-accent);
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.card:hover {
    transform: translateY(-8px);
    border-color: var(--color-accent-start);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

.card:hover::before {
    opacity: 0.05;
}

.card__icon {
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-accent);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-md);
    font-size: 1.5rem;
    transition: transform var(--transition-normal);
}

.card:hover .card__icon {
    transform: scale(1.1) rotate(5deg);
}

.card__title {
    font-size: 1.25rem;
    margin-bottom: var(--space-sm);
}

.card__text {
    font-size: 0.95rem;
    color: var(--color-text-muted);
    line-height: 1.7;
}

/* 卡片网格 */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-lg);
}

/* ==================== 按钮 ==================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-xs);
    padding: var(--space-sm) var(--space-lg);
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-full);
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.btn--primary {
    background: var(--color-accent);
    color: var(--color-text-primary);
    box-shadow: 0 4px 20px rgba(102, 126, 234, 0.4);
}

.btn--primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(102, 126, 234, 0.5);
}

.btn--primary:active {
    transform: translateY(0);
}

.btn--secondary {
    background: var(--color-glass);
    color: var(--color-text-primary);
    border: 1px solid var(--color-glass-border);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

.btn--secondary:hover {
    background: var(--color-glass-hover);
    border-color: var(--color-accent-start);
}

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

.btn--outline:hover {
    border-color: var(--color-accent-start);
    background: rgba(102, 126, 234, 0.1);
}

.btn--large {
    padding: var(--space-md) var(--space-xl);
    font-size: 1.125rem;
}

.btn--small {
    padding: var(--space-xs) var(--space-sm);
    font-size: 0.875rem;
}

/* 按钮涟漪效果 */
.btn__ripple {
    position: absolute;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.3);
    transform: scale(0);
    animation: ripple 0.6s linear;
    pointer-events: none;
}

@keyframes ripple {
    to {
        transform: scale(4);
        opacity: 0;
    }
}

/* ==================== 表单元素 ==================== */
.form-group {
    margin-bottom: var(--space-md);
}

.form-label {
    display: block;
    margin-bottom: var(--space-xs);
    font-weight: 500;
    color: var(--color-text-secondary);
}

.form-input,
.form-textarea,
.form-select {
    width: 100%;
    padding: var(--space-sm);
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-md);
    color: var(--color-text-primary);
    font-size: 1rem;
    transition: all var(--transition-fast);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

.form-input:focus,
.form-textarea:focus,
.form-select:focus {
    outline: none;
    border-color: var(--color-accent-start);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.2);
}

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

.form-textarea {
    min-height: 150px;
    resize: vertical;
}

.form-select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%23a0a0b8' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    background-size: 1rem;
}

/* ==================== 英雄区 ==================== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    padding-top: 80px;
}

.hero__content {
    text-align: center;
    max-width: 900px;
    margin: 0 auto;
}

.hero__badge {
    display: inline-block;
    padding: var(--space-xs) var(--space-md);
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    margin-bottom: var(--space-lg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

.hero__title {
    margin-bottom: var(--space-lg);
    animation: fadeInUp 0.8s ease-out;
}

.hero__subtitle {
    font-size: clamp(1.125rem, 2vw, 1.5rem);
    color: var(--color-text-secondary);
    margin-bottom: var(--space-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    animation: fadeInUp 0.8s ease-out 0.2s backwards;
}

.hero__buttons {
    display: flex;
    gap: var(--space-md);
    justify-content: center;
    flex-wrap: wrap;
    animation: fadeInUp 0.8s ease-out 0.4s backwards;
}

.hero__scroll {
    position: absolute;
    bottom: var(--space-xl);
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-xs);
    color: var(--color-text-muted);
    font-size: 0.875rem;
    animation: bounce 2s infinite;
}

.hero__scroll-icon {
    width: 24px;
    height: 40px;
    border: 2px solid var(--color-glass-border);
    border-radius: var(--radius-full);
    position: relative;
}

.hero__scroll-icon::after {
    content: '';
    position: absolute;
    top: 8px;
    left: 50%;
    transform: translateX(-50%);
    width: 4px;
    height: 8px;
    background: var(--color-accent-start);
    border-radius: var(--radius-full);
    animation: scrollDot 2s infinite;
}

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

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateX(-50%) translateY(0);
    }
    40% {
        transform: translateX(-50%) translateY(-10px);
    }
    60% {
        transform: translateX(-50%) translateY(-5px);
    }
}

@keyframes scrollDot {
    0% {
        opacity: 1;
        top: 8px;
    }
    100% {
        opacity: 0;
        top: 20px;
    }
}

/* ==================== 特性展示 ==================== */
.features {
    padding: var(--space-2xl) 0;
}

.features__header {
    text-align: center;
    margin-bottom: var(--space-2xl);
}

.features__tag {
    display: inline-block;
    padding: var(--space-xs) var(--space-md);
    background: rgba(102, 126, 234, 0.15);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    color: var(--color-accent-start);
    margin-bottom: var(--space-md);
    font-weight: 600;
}

.features__title {
    margin-bottom: var(--space-sm);
}

.features__subtitle {
    max-width: 600px;
    margin: 0 auto;
}

/* ==================== 关于我们 ==================== */
.about {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-2xl);
    align-items: center;
}

.about__image {
    position: relative;
    border-radius: var(--radius-xl);
    overflow: hidden;
}

.about__image-placeholder {
    aspect-ratio: 4/3;
    background: linear-gradient(135deg, var(--color-secondary), var(--color-primary));
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    border-radius: var(--radius-xl);
    border: 1px solid var(--color-glass-border);
}

.about__image-decoration {
    position: absolute;
    width: 150%;
    height: 150%;
    top: -25%;
    left: -25%;
    background: var(--color-accent);
    opacity: 0.1;
    filter: blur(80px);
    pointer-events: none;
}

.about__content {
    padding: var(--space-lg);
}

.about__tag {
    display: inline-block;
    padding: var(--space-xs) var(--space-md);
    background: var(--color-glass);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    color: var(--color-accent-start);
    margin-bottom: var(--space-md);
    border: 1px solid var(--color-glass-border);
}

.about__title {
    margin-bottom: var(--space-md);
}

.about__text {
    margin-bottom: var(--space-lg);
}

.about__stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-md);
    margin-top: var(--space-xl);
}

.stat__number {
    font-family: var(--font-display);
    font-size: 2.5rem;
    font-weight: 800;
    background: var(--color-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

/* ==================== 服务项目 ==================== */
.services {
    text-align: center;
}

.services__header {
    margin-bottom: var(--space-2xl);
}

.services__grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-lg);
    text-align: left;
}

/* ==================== CTA区域 ==================== */
.cta {
    text-align: center;
    position: relative;
}

.cta__box {
    background: var(--color-glass);
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-xl);
    padding: var(--space-2xl);
    position: relative;
    overflow: hidden;
}

.cta__box::before {
    content: '';
    position: absolute;
    inset: 0;
    background: var(--color-accent);
    opacity: 0.05;
}

.cta__title {
    margin-bottom: var(--space-md);
    position: relative;
}

.cta__text {
    max-width: 500px;
    margin: 0 auto var(--space-xl);
    position: relative;
}

.cta__buttons {
    display: flex;
    gap: var(--space-md);
    justify-content: center;
    flex-wrap: wrap;
    position: relative;
}

/* ==================== 页脚 ==================== */
.footer {
    background: var(--color-primary);
    padding: var(--space-2xl) 0 var(--space-lg);
    border-top: 1px solid var(--color-glass-border);
}

.footer__grid {
    display: grid;
    grid-template-columns: 2fr repeat(3, 1fr);
    gap: var(--space-xl);
    margin-bottom: var(--space-xl);
}

.footer__brand {
    max-width: 300px;
}

.footer__logo {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 800;
    background: var(--color-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--space-md);
}

.footer__desc {
    font-size: 0.95rem;
    color: var(--color-text-muted);
    line-height: 1.7;
}

.footer__title {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: var(--space-md);
    color: var(--color-text-primary);
}

.footer__links {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.footer__link {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    transition: color var(--transition-fast);
}

.footer__link:hover {
    color: var(--color-accent-start);
}

.footer__bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--space-lg);
    border-top: 1px solid var(--color-glass-border);
}

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

.footer__socials {
    display: flex;
    gap: var(--space-sm);
}

.footer__social {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-full);
    color: var(--color-text-secondary);
    transition: all var(--transition-fast);
}

.footer__social:hover {
    background: var(--color-accent);
    border-color: var(--color-accent);
    color: var(--color-text-primary);
    transform: translateY(-3px);
}

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

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

.stagger-1 { transition-delay: 0.1s; }
.stagger-2 { transition-delay: 0.2s; }
.stagger-3 { transition-delay: 0.3s; }
.stagger-4 { transition-delay: 0.4s; }
.stagger-5 { transition-delay: 0.5s; }

/* 悬停发光效果 */
.glow-hover {
    transition: all var(--transition-normal);
}

.glow-hover:hover {
    box-shadow: var(--shadow-glow);
}

/* ==================== 响应式设计 ==================== */
@media (max-width: 1200px) {
    :root {
        --space-2xl: 4rem;
    }
    
    .about {
        gap: var(--space-xl);
    }
    
    .footer__grid {
        grid-template-columns: 1fr 1fr;
        gap: var(--space-lg);
    }
}

@media (max-width: 992px) {
    .about {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .about__image {
        order: -1;
        max-width: 500px;
        margin: 0 auto;
    }
    
    .about__stats {
        justify-content: center;
    }
    
    .hero__scroll {
        display: none;
    }
}

@media (max-width: 768px) {
    :root {
        --space-lg: 1.5rem;
        --space-xl: 2rem;
        --space-2xl: 3rem;
    }
    
    .section {
        padding: var(--space-xl) 0;
        min-height: auto;
    }
    
    .hero {
        min-height: 90vh;
        padding-top: 100px;
    }
    
    .card-grid {
        grid-template-columns: 1fr;
    }
    
    .services__grid {
        grid-template-columns: 1fr;
    }
    
    .footer__grid {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .footer__brand {
        max-width: 100%;
    }
    
    .footer__bottom {
        flex-direction: column;
        gap: var(--space-md);
        text-align: center;
    }
    
    .about__stats {
        grid-template-columns: 1fr;
        gap: var(--space-md);
    }
    
    .stat {
        text-align: center;
    }
}

@media (max-width: 480px) {
    :root {
        --space-sm: 0.75rem;
        --space-md: 1rem;
        --space-lg: 1.25rem;
    }
    
    .container {
        padding: 0 var(--space-sm);
    }
    
    .hero__buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .btn {
        width: 100%;
    }
    
    .cta__box {
        padding: var(--space-xl);
    }
}

/* ==================== 辅助类 ==================== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-sm { margin-top: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }

.mb-sm { margin-bottom: var(--space-sm); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.mb-xl { margin-bottom: var(--space-xl); }

.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-sm { gap: var(--space-sm); }
.gap-md { gap: var(--space-md); }
.gap-lg { gap: var(--space-lg); }

.hidden { display: none; }

@media (min-width: 769px) {
    .hidden-desktop { display: none; }
}

@media (max-width: 768px) {
    .hidden-mobile { display: none; }
}
```