/* =====================================================
   Beijing Yuda Teng Sports Development Co., Ltd
   Responsive Stylesheet
   ===================================================== */

/* Large Desktop */
@media (max-width: 1399px) {
    .container {
        max-width: 1200px;
    }
    
    .hero-content {
        max-width: 800px;
    }
    
    .stats {
        grid-template-columns: repeat(4, 1fr);
        gap: var(--space-lg);
    }
    
    .stat-number {
        font-size: 3rem;
    }
    
    .footer-grid {
        grid-template-columns: 2fr 1fr 1fr 1fr;
        gap: var(--space-2xl);
    }
}

/* Desktop */
@media (max-width: 1199px) {
    .container {
        max-width: 960px;
    }
    
    .grid-4 {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .services-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .app-showcase {
        grid-template-columns: 1fr;
        gap: var(--space-2xl);
    }
    
    .app-preview {
        order: -1;
    }
    
    .app-preview-frame {
        max-width: 350px;
    }
    
    .culture-values {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .timeline::before {
        left: 30px;
    }
    
    .timeline-item {
        width: 100%;
        justify-content: flex-start !important;
        margin-left: 60px !important;
        padding-left: var(--space-xl);
    }
    
    .timeline-item::before {
        left: 22px !important;
        right: auto !important;
    }
    
    .contact-grid {
        grid-template-columns: 1fr;
        gap: var(--space-2xl);
    }
    
    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-2xl);
    }
    
    .news-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .ad-platforms-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Tablet Landscape */
@media (max-width: 991px) {
    :root {
        --space-4xl: 4rem;
        --space-3xl: 3rem;
    }
    
    h1 {
        font-size: clamp(2rem, 4vw, 3.5rem);
    }
    
    h2 {
        font-size: clamp(1.75rem, 3vw, 2.5rem);
    }
    
    .navbar-menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 400px;
        height: 100vh;
        background: var(--color-primary);
        flex-direction: column;
        justify-content: center;
        padding: var(--space-2xl);
        transition: var(--transition-normal);
        box-shadow: var(--shadow-xl);
    }
    
    .navbar-menu.active {
        right: 0;
    }
    
    .navbar-menu a {
        font-size: 1.25rem;
        padding: var(--space-md) 0;
    }
    
    .navbar-toggle {
        display: flex;
        z-index: 1001;
    }
    
    .mobile-menu-overlay {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background: rgba(0, 0, 0, 0.5);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition-normal);
        z-index: 999;
    }
    
    .mobile-menu-overlay.active {
        opacity: 1;
        visibility: visible;
    }
    
    .hero {
        min-height: 100vh;
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .stats {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .stat-item:nth-child(2)::after {
        display: none;
    }
    
    .section-header .subtitle::before,
    .section-header .subtitle::after {
        width: 20px;
    }
    
    .page-header {
        padding: 150px 0 80px;
    }
}

/* Tablet Portrait */
@media (max-width: 767px) {
    :root {
        --space-4xl: 3rem;
        --space-3xl: 2.5rem;
        --space-2xl: 2rem;
    }
    
    .container {
        padding: 0 var(--space-md);
    }
    
    .grid-2,
    .grid-3 {
        grid-template-columns: 1fr;
    }
    
    .services-grid {
        grid-template-columns: 1fr;
    }
    
    .service-card {
        max-width: 500px;
        margin: 0 auto;
    }
    
    .culture-values {
        grid-template-columns: 1fr;
        gap: var(--space-lg);
    }
    
    .value-item {
        max-width: 400px;
        margin: 0 auto;
    }
    
    .news-grid {
        grid-template-columns: 1fr;
        max-width: 500px;
        margin: 0 auto;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .footer-brand {
        justify-content: center;
    }
    
    .footer-social {
        justify-content: center;
    }
    
    .footer-links {
        display: flex;
        flex-direction: column;
        align-items: center;
    }
    
    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
    
    .footer-legal {
        flex-direction: column;
        gap: var(--space-sm);
    }
    
    .contact-info {
        padding: var(--space-xl);
    }
    
    .contact-form {
        padding: var(--space-xl);
    }
    
    .app-buttons {
        flex-direction: column;
    }
    
    .app-button {
        justify-content: center;
    }
    
    .app-preview-frame {
        max-width: 300px;
    }
    
    .ad-platforms-grid {
        grid-template-columns: 1fr;
    }
    
    .ad-formats-grid {
        grid-template-columns: 1fr;
    }
    
    .compliance-badges {
        justify-content: center;
    }
    
    .table-container {
        font-size: 0.875rem;
    }
    
    th, td {
        padding: var(--space-sm);
    }
    
    .legal-content {
        padding: var(--space-2xl) var(--space-md);
    }
    
    .legal-content h2 {
        font-size: 1.5rem;
    }
    
    .legal-content h3 {
        font-size: 1.25rem;
    }
}

/* Mobile Landscape */
@media (max-width: 575px) {
    :root {
        --space-4xl: 2.5rem;
        --space-3xl: 2rem;
        --space-2xl: 1.5rem;
        --space-xl: 1rem;
    }
    
    .navbar-brand svg {
        height: 40px;
    }
    
    .navbar-brand-text {
        font-size: 1rem;
    }
    
    .hero-badge {
        font-size: 0.75rem;
        padding: var(--space-xs) var(--space-md);
    }
    
    .hero h1 {
        font-size: clamp(1.75rem, 6vw, 2.5rem);
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .btn {
        padding: var(--space-sm) var(--space-lg);
        font-size: 0.875rem;
    }
    
    .stats {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--space-md);
    }
    
    .stat-item {
        padding: var(--space-md);
    }
    
    .stat-number {
        font-size: 2.5rem;
    }
    
    .stat-label {
        font-size: 0.75rem;
    }
    
    .card {
        padding: var(--space-lg);
    }
    
    .service-card {
        padding: var(--space-xl);
    }
    
    .service-icon {
        width: 60px;
        height: 60px;
    }
    
    .service-icon svg {
        width: 30px;
        height: 30px;
    }
    
    .news-image {
        height: 160px;
    }
    
    .news-content {
        padding: var(--space-md);
    }
    
    .news-title {
        font-size: 1rem;
    }
    
    .timeline-content {
        padding: var(--space-md);
        margin: 0 var(--space-md);
    }
    
    .timeline-year {
        font-size: 1.25rem;
    }
    
    .timeline-title {
        font-size: 1rem;
    }
    
    .page-header {
        padding: 130px 0 60px;
    }
    
    .page-header h1 {
        font-size: 1.75rem;
    }
    
    .form-group input,
    .form-group textarea {
        padding: var(--space-sm);
    }
    
    .back-to-top {
        width: 40px;
        height: 40px;
        bottom: 20px;
        right: 20px;
    }
}

/* Extra Small Mobile */
@media (max-width: 375px) {
    .navbar-brand-text {
        display: none;
    }
    
    .hero-content {
        padding: 0 var(--space-sm);
    }
    
    .stats {
        gap: var(--space-sm);
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    .section-header .subtitle::before,
    .section-header .subtitle::after {
        display: none;
    }
    
    .footer-brand svg {
        height: 50px;
    }
    
    .app-preview-frame {
        max-width: 260px;
        padding: 15px;
    }
    
    .app-preview-screen {
        border-radius: 20px;
    }
}

/* Print Styles */
@media print {
    .navbar,
    .back-to-top,
    .hero-scroll,
    .loading-screen {
        display: none !important;
    }
    
    .hero {
        min-height: auto;
        padding: var(--space-2xl) 0;
    }
    
    .section {
        padding: var(--space-xl) 0;
    }
    
    .card,
    .service-card,
    .news-card {
        break-inside: avoid;
        box-shadow: none;
        border: 1px solid var(--color-gray-300);
    }
    
    a {
        text-decoration: underline;
    }
    
    .footer {
        background: var(--color-gray-100);
        color: var(--color-gray-900);
    }
}

/* Accessibility - Reduced Motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    [data-animate] {
        opacity: 1;
        transform: none;
    }
    
    html {
        scroll-behavior: auto;
    }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
    :root {
        --color-accent: #ffd700;
        --color-gray-300: #cccccc;
        --color-gray-600: #666666;
    }
    
    .card,
    .service-card,
    .news-card {
        border: 2px solid var(--color-gray-800);
    }
    
    .btn {
        border: 2px solid currentColor;
    }
}

/* Dark Mode Support (if system prefers) */
@media (prefers-color-scheme: dark) {
    /* Can be customized based on requirements */
}

/* Orientation Changes */
@media (orientation: landscape) and (max-height: 500px) {
    .hero {
        min-height: auto;
        padding: var(--space-3xl) 0;
    }
    
    .hero-scroll {
        display: none;
    }
    
    .page-header {
        padding: 100px 0 40px;
    }
}

/* Touch Device Optimizations */
@media (hover: none) and (pointer: coarse) {
    .btn:hover {
        transform: none;
    }
    
    .card:hover {
        transform: none;
    }
    
    .service-card:hover {
        transform: none;
    }
    
    .navbar-menu a:hover::after {
        width: 0;
    }
    
    .navbar-menu a:hover {
        color: var(--color-accent);
    }
}

/* Large Touch Targets */
@media (pointer: coarse) {
    .navbar-toggle {
        padding: 15px;
    }
    
    .btn {
        min-height: 48px;
        min-width: 48px;
    }
    
    .form-group input,
    .form-group textarea {
        min-height: 48px;
    }
    
    .contact-icon {
        width: 60px;
        height: 60px;
    }
    
    .service-icon {
        width: 80px;
        height: 80px;
    }
}

/* Focus Visible for Keyboard Navigation */
:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* Skip Link */
.skip-link {
    position: absolute;
    top: -100%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--color-accent);
    color: var(--color-white);
    padding: var(--space-sm) var(--space-md);
    z-index: 10000;
    transition: top 0.3s ease;
}

.skip-link:focus {
    top: 10px;
}

/* Screen Reader Only */
.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;
}

/* Cursor Styles */
@media (hover: hover) {
    a[href],
    button,
    [role="button"] {
        cursor: pointer;
    }
}

/* Smooth Scroll Lock for Animations */
.scroll-locked {
    overflow: hidden;
}

/* Firefox Specific */
@-moz-document url-prefix() {
    .hero-background::before {
        background: rgba(0, 0, 0, 0.7);
    }
}

/* Safari Specific */
@supports (-webkit-touch-callout: none) {
    .hero-background {
        -webkit-transform: translateZ(0);
        transform: translateZ(0);
    }
}

/* IE11 Fallbacks */
@media all and (-ms-high-contrast: none), (-ms-high-contrast: active) {
    .grid {
        display: -ms-grid;
    }
    
    [data-animate] {
        opacity: 1;
        transform: none;
    }
}