/* ============================================
   Beijing Xinqi Technology Co., Ltd.
   Responsive Styles
   ============================================ */

/* ============================================
   LARGE DESKTOP (1400px and above)
   ============================================ */
@media screen and (min-width: 1400px) {
    .container {
        max-width: 1320px;
    }
    
    .hero h1 {
        font-size: 5rem;
    }
    
    .services-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* ============================================
   DESKTOP (1024px - 1399px)
   ============================================ */
@media screen and (max-width: 1399px) {
    :root {
        --spacing-unit: 18px;
    }
    
    .footer-content {
        grid-template-columns: 2fr 1fr 1fr;
    }
    
    .about-grid {
        gap: calc(var(--spacing-unit) * 3);
    }
}

/* ============================================
   TABLET LANDSCAPE (992px - 1023px)
   ============================================ */
@media screen and (max-width: 1023px) {
    :root {
        --spacing-unit: 16px;
    }
    
    /* Navigation */
    .nav-list {
        display: none;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    /* Hero */
    .hero {
        min-height: 600px;
    }
    
    .hero h1 {
        font-size: 3rem;
    }
    
    .hero-subtitle {
        font-size: 1.1rem;
    }
    
    /* About */
    .about-grid {
        grid-template-columns: 1fr;
        gap: calc(var(--spacing-unit) * 3);
    }
    
    .about-stats {
        grid-template-columns: repeat(3, 1fr);
    }
    
    /* App Showcase */
    .app-showcase {
        grid-template-columns: 1fr;
        gap: calc(var(--spacing-unit) * 3);
    }
    
    .app-preview {
        order: -1;
    }
    
    .phone-mockup {
        width: 260px;
        height: 520px;
    }
    
    /* Contact */
    .contact-wrapper {
        grid-template-columns: 1fr;
    }
    
    /* Footer */
    .footer-content {
        grid-template-columns: 1fr 1fr;
        gap: calc(var(--spacing-unit) * 2);
    }
    
    .footer-about {
        grid-column: span 2;
    }
    
    /* Timeline */
    .timeline::before {
        left: 20px;
    }
    
    .timeline-item {
        width: 100%;
        padding-left: 50px;
        padding-right: 0;
        text-align: left;
    }
    
    .timeline-item:nth-child(even) {
        margin-left: 0;
    }
    
    .timeline-dot {
        left: 12px !important;
        right: auto !important;
    }
    
    .timeline-item:nth-child(odd) {
        padding-right: 0;
        text-align: left;
    }
}

/* ============================================
   TABLET PORTRAIT (768px - 991px)
   ============================================ */
@media screen and (max-width: 991px) {
    :root {
        --spacing-unit: 15px;
    }
    
    /* Sections */
    .section {
        padding: calc(var(--spacing-unit) * 5) 0;
    }
    
    /* Services Grid */
    .services-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: calc(var(--spacing-unit) * 1.5);
    }
    
    /* Features Grid */
    .features-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: calc(var(--spacing-unit) * 2);
    }
    
    /* News Grid */
    .news-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    /* Culture Grid */
    .culture-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    /* Ads Platforms */
    .ads-platforms {
        grid-template-columns: repeat(3, 1fr);
    }
    
    /* About Stats */
    .about-stats {
        grid-template-columns: repeat(3, 1fr);
        gap: calc(var(--spacing-unit) * 1.5);
    }
    
    .stat-number {
        font-size: 2.5rem;
    }
    
    /* Footer */
    .footer-content {
        grid-template-columns: 1fr 1fr;
    }
    
    .footer-about {
        grid-column: span 2;
    }
    
    /* Page Header */
    .page-header {
        min-height: 350px;
    }
}

/* ============================================
   MOBILE LANDSCAPE (600px - 767px)
   ============================================ */
@media screen and (max-width: 767px) {
    :root {
        --spacing-unit: 14px;
    }
    
    /* Typography */
    h1 {
        font-size: clamp(2rem, 6vw, 3rem);
    }
    
    h2 {
        font-size: clamp(1.5rem, 4vw, 2rem);
    }
    
    h3 {
        font-size: 1.3rem;
    }
    
    p {
        font-size: 1rem;
    }
    
    /* Header */
    .header {
        padding: calc(var(--spacing-unit) * 1) 0;
    }
    
    .logo svg {
        width: 40px;
        height: 40px;
    }
    
    .logo-text {
        font-size: 1rem;
    }
    
    /* Hero */
    .hero {
        min-height: 500px;
    }
    
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .hero-badge {
        padding: 8px 20px;
        font-size: 0.7rem;
    }
    
    .hero-cta {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        padding: 15px 35px;
        font-size: 0.85rem;
        width: 100%;
        max-width: 280px;
    }
    
    .scroll-indicator {
        bottom: 30px;
    }
    
    /* Services */
    .services-grid {
        grid-template-columns: 1fr;
    }
    
    .service-card {
        padding: calc(var(--spacing-unit) * 2);
    }
    
    .service-icon {
        width: 60px;
        height: 60px;
    }
    
    /* Features */
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .feature-icon {
        width: 70px;
        height: 70px;
    }
    
    /* News */
    .news-grid {
        grid-template-columns: 1fr;
    }
    
    .news-image {
        height: 180px;
    }
    
    /* Culture */
    .culture-grid {
        grid-template-columns: 1fr;
    }
    
    .culture-icon {
        width: 80px;
        height: 80px;
    }
    
    /* App Showcase */
    .phone-mockup {
        width: 220px;
        height: 440px;
        border-radius: 30px;
    }
    
    .phone-mockup::before {
        width: 60px;
        height: 20px;
        top: 18px;
    }
    
    .phone-screen {
        border-radius: 22px;
    }
    
    /* Ads Platforms */
    .ads-platforms {
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-unit);
    }
    
    .ad-platform {
        padding: calc(var(--spacing-unit) * 1.5);
    }
    
    .ad-platform-icon {
        width: 50px;
        height: 50px;
    }
    
    /* About */
    .about-stats {
        grid-template-columns: 1fr;
        gap: var(--spacing-unit);
    }
    
    .stat-item {
        padding: calc(var(--spacing-unit) * 1);
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    /* Contact */
    .contact-wrapper {
        gap: calc(var(--spacing-unit) * 2);
    }
    
    .contact-info,
    .contact-form {
        padding: calc(var(--spacing-unit) * 2);
    }
    
    /* Footer */
    .footer-content {
        grid-template-columns: 1fr;
        gap: calc(var(--spacing-unit) * 2);
    }
    
    .footer-about {
        grid-column: auto;
    }
    
    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
    
    .footer-legal {
        flex-direction: column;
        gap: 10px;
    }
    
    /* Page Header */
    .page-header {
        min-height: 300px;
        padding-top: 80px;
    }
    
    .page-header h1 {
        font-size: 2rem;
    }
    
    .breadcrumb {
        flex-wrap: wrap;
        font-size: 0.8rem;
    }
    
    /* Legal Content */
    .legal-content {
        padding: calc(var(--spacing-unit) * 3) 0;
    }
    
    .legal-content h2 {
        font-size: 1.4rem;
    }
    
    .legal-content h3 {
        font-size: 1.1rem;
    }
    
    .legal-content p {
        font-size: 0.95rem;
    }
    
    /* Timeline */
    .timeline {
        padding-left: 20px;
    }
    
    .timeline::before {
        left: 10px;
    }
    
    .timeline-dot {
        width: 12px;
        height: 12px;
        left: 2px !important;
    }
    
    .timeline-year {
        font-size: 1.5rem;
    }
    
    /* Particles */
    .particle {
        width: 3px;
        height: 3px;
    }
}

/* ============================================
   MOBILE PORTRAIT (320px - 599px)
   ============================================ */
@media screen and (max-width: 599px) {
    :root {
        --spacing-unit: 12px;
    }
    
    /* Container */
    .container {
        padding: 0 calc(var(--spacing-unit) * 1.5);
    }
    
    /* Typography */
    h1 {
        font-size: clamp(1.8rem, 7vw, 2.5rem);
    }
    
    h2 {
        font-size: clamp(1.3rem, 5vw, 1.8rem);
    }
    
    p {
        font-size: 0.95rem;
        line-height: 1.7;
    }
    
    /* Header */
    .header {
        padding: calc(var(--spacing-unit) * 0.8) 0;
    }
    
    .logo svg {
        width: 35px;
        height: 35px;
    }
    
    .logo-text {
        font-size: 0.9rem;
    }
    
    .logo-text span {
        font-size: 0.6rem;
    }
    
    .mobile-menu-btn {
        padding: 8px;
    }
    
    .mobile-menu-btn span {
        width: 25px;
        height: 2px;
    }
    
    /* Hero */
    .hero {
        min-height: 100vh;
    }
    
    .hero-content {
        padding: 0 15px;
    }
    
    .hero-badge {
        padding: 6px 15px;
        font-size: 0.65rem;
        letter-spacing: 0.2em;
    }
    
    .hero h1 {
        font-size: 2rem;
        margin-bottom: calc(var(--spacing-unit) * 1.5);
    }
    
    .hero-subtitle {
        font-size: 0.9rem;
        margin-bottom: calc(var(--spacing-unit) * 2);
    }
    
    .btn {
        padding: 12px 25px;
        font-size: 0.8rem;
    }
    
    .scroll-indicator {
        bottom: 20px;
        font-size: 0.7rem;
    }
    
    .scroll-indicator svg {
        width: 24px;
        height: 24px;
    }
    
    /* Section Title */
    .section-title {
        margin-bottom: calc(var(--spacing-unit) * 3);
    }
    
    .section-title .subtitle {
        font-size: 0.75rem;
        letter-spacing: 0.2em;
    }
    
    /* Services */
    .section {
        padding: calc(var(--spacing-unit) * 4) 0;
    }
    
    .service-card {
        padding: calc(var(--spacing-unit) * 1.5);
    }
    
    .service-icon {
        width: 50px;
        height: 50px;
        margin-bottom: calc(var(--spacing-unit) * 1.5);
    }
    
    .service-card h3 {
        font-size: 1.2rem;
        margin-bottom: calc(var(--spacing-unit) * 0.8);
    }
    
    /* Features */
    .feature-icon {
        width: 60px;
        height: 60px;
    }
    
    .feature-icon svg {
        width: 30px;
        height: 30px;
    }
    
    /* News */
    .news-image {
        height: 150px;
    }
    
    .news-image svg {
        width: 60px;
        height: 60px;
    }
    
    .news-content {
        padding: calc(var(--spacing-unit) * 1.5);
    }
    
    .news-card h3 {
        font-size: 1.1rem;
    }
    
    .news-date {
        font-size: 0.75rem;
    }
    
    /* Culture */
    .culture-card {
        padding: calc(var(--spacing-unit) * 2);
    }
    
    .culture-icon {
        width: 70px;
        height: 70px;
    }
    
    /* App Showcase */
    .app-content h2 {
        font-size: 1.5rem;
    }
    
    .phone-mockup {
        width: 180px;
        height: 360px;
        border-radius: 25px;
        padding: 10px;
    }
    
    .phone-mockup::before {
        width: 50px;
        height: 16px;
        top: 14px;
    }
    
    .phone-screen {
        border-radius: 18px;
    }
    
    .store-buttons {
        flex-direction: column;
    }
    
    .store-btn {
        width: 100%;
        justify-content: center;
    }
    
    /* Ads Platforms */
    .ads-platforms {
        grid-template-columns: 1fr 1fr;
    }
    
    .ad-platform {
        padding: var(--spacing-unit);
    }
    
    .ad-platform-icon {
        width: 45px;
        height: 45px;
    }
    
    .ad-platform-icon svg {
        width: 24px;
        height: 24px;
    }
    
    .ad-platform h4 {
        font-size: 0.9rem;
    }
    
    .ad-platform p {
        font-size: 0.75rem;
    }
    
    /* About */
    .about-stats {
        grid-template-columns: 1fr;
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    .stat-label {
        font-size: 0.75rem;
    }
    
    /* Contact */
    .contact-info h3,
    .contact-form h3 {
        font-size: 1.2rem;
    }
    
    .form-group input,
    .form-group textarea {
        padding: 12px;
        font-size: 0.95rem;
    }
    
    .form-group textarea {
        min-height: 120px;
    }
    
    /* Footer */
    .footer {
        padding: calc(var(--spacing-unit) * 3) 0 calc(var(--spacing-unit) * 1.5);
    }
    
    .footer-links h4 {
        font-size: 1rem;
    }
    
    .footer-links a {
        font-size: 0.85rem;
    }
    
    .footer-bottom p {
        font-size: 0.8rem;
    }
    
    /* Page Header */
    .page-header {
        min-height: 250px;
        padding-top: 70px;
    }
    
    .page-header h1 {
        font-size: 1.8rem;
    }
    
    .breadcrumb {
        font-size: 0.7rem;
        gap: 10px;
    }
    
    /* Legal Content */
    .legal-content {
        padding: calc(var(--spacing-unit) * 2) 0;
    }
    
    .legal-content h2 {
        font-size: 1.3rem;
        margin-top: calc(var(--spacing-unit) * 2);
    }
    
    .legal-content h3 {
        font-size: 1rem;
    }
    
    .legal-content p {
        font-size: 0.9rem;
    }
    
    .legal-content ul {
        padding-left: calc(var(--spacing-unit) * 1.5);
    }
    
    .legal-content ul li {
        font-size: 0.9rem;
    }
    
    /* Timeline */
    .timeline-year {
        font-size: 1.3rem;
    }
    
    .timeline-item h4 {
        font-size: 1rem;
    }
    
    .timeline-item p {
        font-size: 0.85rem;
    }
    
    /* Modal */
    .modal-content {
        max-width: 95%;
        padding: 15px;
    }
}

/* ============================================
   VERY SMALL SCREENS (below 320px)
   ============================================ */
@media screen and (max-width: 349px) {
    :root {
        --spacing-unit: 10px;
    }
    
    h1 {
        font-size: 1.5rem;
    }
    
    h2 {
        font-size: 1.2rem;
    }
    
    .hero h1 {
        font-size: 1.8rem;
    }
    
    .hero-subtitle {
        font-size: 0.85rem;
    }
    
    .btn {
        padding: 10px 20px;
        font-size: 0.75rem;
    }
    
    .phone-mockup {
        width: 160px;
        height: 320px;
    }
}

/* ============================================
   HIGH DPI DISPLAYS
   ============================================ */
@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
    /* Sharper text rendering */
    body {
        -webkit-font-smoothing: antialiased;
        -moz-osx-font-smoothing: grayscale;
    }
    
    /* Crisp borders */
    .service-card,
    .news-card,
    .culture-card {
        border-width: 1px;
    }
}

/* ============================================
   REDUCED MOTION
   ============================================ */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    html {
        scroll-behavior: auto;
    }
    
    .particle {
        animation: none;
    }
    
    .scroll-indicator svg {
        animation: none;
    }
}

/* ============================================
   DARK MODE (system preference)
   ============================================ */
@media (prefers-color-scheme: dark) {
    /* Already dark by default, but ensuring consistency */
    :root {
        --color-black: #0a0a0a;
        --color-black-light: #1a1a1a;
        --color-black-lighter: #2a2a2a;
    }
}

/* ============================================
   PRINT STYLES
   ============================================ */
@media print {
    .header,
    .footer,
    .scroll-indicator,
    .mobile-menu-btn,
    .hero-cta,
    .btn,
    .form-group,
    .contact-form,
    .store-buttons {
        display: none !important;
    }
    
    body {
        background: white;
        color: black;
    }
    
    .hero {
        height: auto;
        min-height: auto;
        padding: 50px 0;
    }
    
    .section {
        padding: 30px 0;
    }
    
    h1, h2, h3, h4, h5, h6 {
        color: black;
    }
    
    p {
        color: #333;
    }
    
    .service-card,
    .news-card,
    .culture-card {
        border: 1px solid #ccc;
        background: white;
    }
}

/* ============================================
   ACCESSIBILITY
   ============================================ */

/* Focus styles for keyboard navigation */
a:focus,
button:focus,
input:focus,
textarea:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* Skip to content link */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-primary);
    color: var(--color-black);
    padding: 10px 20px;
    z-index: 10000;
    transition: top 0.3s ease;
}

.skip-link:focus {
    top: 0;
}

/* 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;
}

/* Larger touch targets for mobile */
@media (hover: none) and (pointer: coarse) {
    .nav-item a,
    .btn,
    .service-card,
    .news-card,
    .culture-card {
        min-height: 44px;
    }
    
    .contact-item {
        min-height: 44px;
    }
}