/* ======================
   DeepSeek R2 Landing Page
   Enhanced Modern Stylesheet
   ====================== */

/* CSS Variables - DeepSeek Modern Theme */
:root {
    /* Primary Colors - Gradient Blues & Purples */
    --primary-blue: #3B82F6;
    --primary-purple: #8B5CF6;
    --primary-pink: #EC4899;
    --primary-indigo: #6366F1;
    
    /* Neutral Colors */
    --white: #FFFFFF;
    --gray-50: #F9FAFB;
    --gray-100: #F3F4F6;
    --gray-200: #E5E7EB;
    --gray-300: #D1D5DB;
    --gray-400: #9CA3AF;
    --gray-500: #6B7280;
    --gray-600: #4B5563;
    --gray-700: #374151;
    --gray-800: #1F2937;
    --gray-900: #111827;
    --black: #000000;
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    
    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    --radius-2xl: 2rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--primary-blue), var(--primary-purple));
    --gradient-secondary: linear-gradient(135deg, var(--primary-purple), var(--primary-pink));
    --gradient-accent: linear-gradient(135deg, var(--primary-blue), var(--primary-indigo), var(--primary-purple));
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
    font-family: var(--font-primary);
    font-size: 1rem;
    line-height: 1.6;
    color: var(--gray-800);
    background-color: var(--white);
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    color: var(--gray-900);
}

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

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

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

/* ======================
   Header & Navigation
   ====================== */

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    transition: all var(--transition-base);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: center;
    cursor: pointer;
}

.logo-img {
    height: 36px;
    width: auto;
    flex-shrink: 0;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--gray-900);
    letter-spacing: -0.01em;
}

.logo-highlight {
    color: #4B6FFF;
    font-weight: 800;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.nav-link {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--gray-700);
    transition: color var(--transition-base);
    position: relative;
}

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

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

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

.lang-switch {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: var(--gray-100);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--gray-700);
    transition: all var(--transition-base);
}

.lang-switch:hover {
    background: var(--gray-200);
    transform: translateY(-2px);
}

.lang-icon {
    font-size: 1.125rem;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 0.5rem;
    cursor: pointer;
}

.mobile-menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--gray-700);
    border-radius: 2px;
    transition: all var(--transition-base);
}

/* ======================
   Buttons
   ====================== */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.75rem;
    font-size: 0.95rem;
    font-weight: 600;
    border-radius: var(--radius-lg);
    transition: all var(--transition-base);
    cursor: pointer;
    white-space: nowrap;
}

.btn-primary {
    background: var(--gradient-primary);
    color: var(--white);
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.4);
}

.btn-secondary {
    background: transparent;
    color: var(--gray-700);
    border: 2px solid var(--gray-300);
}

.btn-secondary:hover {
    background: var(--gray-50);
    border-color: var(--primary-blue);
    color: var(--primary-blue);
}

.btn-white {
    background: var(--white);
    color: var(--primary-blue);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.btn-white:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.05rem;
}

.nav-cta {
    margin-left: 1rem;
}

/* ======================
   Hero Section
   ====================== */

.hero {
    position: relative;
    padding: 10rem 2rem 6rem;
    min-height: 100vh;
    display: flex;
    align-items: center;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: -1;
}

.hero-grid {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        linear-gradient(rgba(59, 130, 246, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(59, 130, 246, 0.03) 1px, transparent 1px);
    background-size: 50px 50px;
    animation: gridMove 20s linear infinite;
}

@keyframes gridMove {
    0% {
        transform: translate(0, 0);
    }
    100% {
        transform: translate(50px, 50px);
    }
}

.hero-gradient {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 30% 50%, rgba(59, 130, 246, 0.08) 0%, transparent 50%),
                radial-gradient(circle at 70% 70%, rgba(139, 92, 246, 0.08) 0%, transparent 50%);
}

.hero-container {
    max-width: 1400px;
    margin: 0 auto;
    width: 100%;
    text-align: center;
}

.hero-content {
    max-width: 900px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1.5rem;
    background: rgba(59, 130, 246, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(59, 130, 246, 0.2);
    border-radius: var(--radius-full);
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--primary-blue);
    animation: badgePulse 2s ease-in-out infinite;
}

@keyframes badgePulse {
    0%, 100% {
        transform: scale(1);
        box-shadow: 0 0 0 0 rgba(59, 130, 246, 0.4);
    }
    50% {
        transform: scale(1.02);
        box-shadow: 0 0 0 10px rgba(59, 130, 246, 0);
    }
}

.badge-dot {
    width: 8px;
    height: 8px;
    background: var(--primary-blue);
    border-radius: 50%;
    animation: dotPulse 2s ease-in-out infinite;
}

@keyframes dotPulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.hero-title {
    font-size: 4.5rem;
    font-weight: 900;
    line-height: 1.1;
    letter-spacing: -0.03em;
    color: var(--gray-900);
}

.gradient-text {
    display: block;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-top: 0.5rem;
    animation: gradientShift 8s ease infinite;
    background-size: 200% 200%;
}

@keyframes gradientShift {
    0%, 100% {
        background-position: 0% 50%;
    }
    50% {
        background-position: 100% 50%;
    }
}

.hero-description {
    font-size: 1.35rem;
    line-height: 1.7;
    color: var(--gray-600);
    max-width: 700px;
}

.hero-cta {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    justify-content: center;
    margin-top: 1rem;
}

.hero-stats {
    display: flex;
    gap: 4rem;
    margin-top: 2rem;
    flex-wrap: wrap;
    justify-content: center;
}

.stat-item {
    text-align: center;
}

.stat-value {
    font-size: 2.5rem;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.95rem;
    color: var(--gray-600);
    margin-top: 0.5rem;
    font-weight: 500;
}

/* ======================
   Sections
   ====================== */

.section {
    padding: 6rem 2rem;
    position: relative;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-badge {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: rgba(59, 130, 246, 0.1);
    color: var(--primary-blue);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.section-title {
    font-size: 3rem;
    margin-bottom: 1rem;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.section-description {
    font-size: 1.25rem;
    color: var(--gray-600);
    max-width: 700px;
    margin: 0 auto;
    line-height: 1.7;
}

/* ======================
   Features Section
   ====================== */

.features-section {
    background: var(--gray-50);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
}

.feature-card {
    padding: 2.5rem;
    background: var(--white);
    border-radius: var(--radius-xl);
    border: 1px solid var(--gray-200);
    transition: all var(--transition-base);
    cursor: pointer;
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.08);
    border-color: rgba(59, 130, 246, 0.3);
}

.feature-icon-wrapper {
    width: 64px;
    height: 64px;
    background: var(--gradient-primary);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
    box-shadow: 0 10px 25px rgba(59, 130, 246, 0.2);
}

.feature-icon {
    font-size: 2rem;
    filter: grayscale(1) brightness(10);
}

.feature-title {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.feature-description {
    color: var(--gray-600);
    line-height: 1.7;
    font-size: 1.05rem;
}

/* ======================
   Comparison Section
   ====================== */

.comparison-section {
    background: var(--white);
}

.comparison-cards {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 3rem;
    align-items: center;
}

.comparison-card {
    padding: 3rem;
    background: var(--white);
    border-radius: var(--radius-2xl);
    border: 2px solid var(--gray-200);
    transition: all var(--transition-base);
    position: relative;
}

.comparison-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.r1-card {
    background: linear-gradient(135deg, rgba(107, 114, 128, 0.05), rgba(156, 163, 175, 0.05));
}

.r2-card {
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.05), rgba(139, 92, 246, 0.05));
    border-color: rgba(59, 130, 246, 0.3);
}

.r2-card:hover {
    border-color: rgba(59, 130, 246, 0.5);
}

.card-badge {
    position: absolute;
    top: -12px;
    left: 3rem;
    padding: 0.5rem 1rem;
    background: var(--gray-500);
    color: var(--white);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    font-weight: 700;
    letter-spacing: 0.05em;
}

.gradient-badge {
    background: var(--gradient-primary);
}

.card-title {
    font-size: 2rem;
    margin: 2rem 0 1rem;
    font-weight: 800;
}

.card-description {
    color: var(--gray-600);
    line-height: 1.7;
    margin-bottom: 2rem;
    font-size: 1.05rem;
}

.card-features {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.card-features li {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--gray-700);
    font-size: 1.05rem;
}

.card-features svg {
    flex-shrink: 0;
    stroke: var(--primary-blue);
}

.comparison-arrow {
    display: flex;
    align-items: center;
    justify-content: center;
}

/* ======================
   Capabilities Section
   ====================== */

.capabilities-section {
    background: var(--gray-50);
}

.capabilities-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.capability-item {
    padding: 2.5rem;
    background: var(--white);
    border-radius: var(--radius-xl);
    border: 1px solid var(--gray-200);
    transition: all var(--transition-base);
}

.capability-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(59, 130, 246, 0.3);
}

.capability-icon {
    font-size: 3rem;
    margin-bottom: 1.5rem;
    display: inline-block;
}

.capability-title {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
}

.capability-description {
    color: var(--gray-600);
    line-height: 1.7;
    font-size: 1.05rem;
}

/* ======================
   FAQ Section
   ====================== */

.faq-section {
    background: var(--white);
}

.faq-list {
    max-width: 900px;
    margin: 0 auto;
}

.faq-item {
    background: var(--white);
    border-radius: var(--radius-lg);
    margin-bottom: 1rem;
    border: 2px solid var(--gray-200);
    overflow: hidden;
    transition: all var(--transition-base);
}

.faq-item:hover {
    border-color: rgba(59, 130, 246, 0.3);
}

.faq-item.active {
    border-color: var(--primary-blue);
}

.faq-question {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1.75rem 2rem;
    cursor: pointer;
    transition: background var(--transition-base);
}

.faq-question:hover {
    background: var(--gray-50);
}

.faq-question h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-900);
    flex: 1;
}

.faq-toggle {
    flex-shrink: 0;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-blue);
    transition: transform var(--transition-base);
}

.faq-item.active .faq-toggle {
    transform: rotate(180deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-slow);
}

.faq-item.active .faq-answer {
    max-height: 500px;
}

.faq-answer p {
    padding: 0 2rem 2rem;
    color: var(--gray-600);
    line-height: 1.8;
    font-size: 1.05rem;
}

/* ======================
   CTA Section
   ====================== */

.cta-section {
    background: var(--gradient-accent);
    color: var(--white);
    padding: 6rem 2rem;
    position: relative;
    overflow: hidden;
}

.cta-bg {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 0;
}

.cta-grid {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        linear-gradient(rgba(255, 255, 255, 0.05) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.05) 1px, transparent 1px);
    background-size: 40px 40px;
}

.cta-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

.cta-title {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--white);
    font-weight: 800;
    letter-spacing: -0.02em;
}

.cta-description {
    font-size: 1.35rem;
    margin-bottom: 2.5rem;
    opacity: 0.95;
    line-height: 1.7;
}

.cta-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
}

/* ======================
   Footer
   ====================== */

.footer {
    background: var(--gray-900);
    color: var(--gray-400);
    padding: 4rem 2rem 2rem;
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 2fr repeat(3, 1fr);
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-logo {
    display: flex;
    align-items: center;
    margin-bottom: 1rem;
}

.footer-logo .logo-img {
    height: 32px;
    width: auto;
}

.footer-logo .logo-text {
    font-size: 1.5rem;
    color: var(--white);
}

.footer-description {
    margin-top: 1rem;
    color: var(--gray-500);
    line-height: 1.7;
    font-size: 1.05rem;
}

.footer-title {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--white);
    margin-bottom: 1.25rem;
}

.footer-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.footer-links a {
    color: var(--gray-400);
    transition: color var(--transition-base);
    font-size: 1rem;
}

.footer-links a:hover {
    color: var(--white);
}

.footer-bottom {
    max-width: 1400px;
    margin: 0 auto;
    padding-top: 2rem;
    border-top: 1px solid var(--gray-800);
    text-align: center;
    color: var(--gray-500);
    font-size: 0.95rem;
    line-height: 1.7;
}

.footer-disclaimer {
    margin-top: 0.5rem;
    font-size: 0.875rem;
    color: var(--gray-600);
}

/* ======================
   Responsive Design
   ====================== */

@media (max-width: 1200px) {
    .comparison-cards {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .comparison-arrow {
        transform: rotate(90deg);
    }
}

@media (max-width: 1024px) {
    .hero-title {
        font-size: 3.5rem;
    }
    
    .section-title {
        font-size: 2.5rem;
    }
    
    .cta-title {
        font-size: 2.5rem;
    }
    
    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .nav-links {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        padding: 2rem;
        box-shadow: var(--shadow-2xl);
        border-top: 1px solid var(--gray-200);
        transform: translateX(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
        z-index: 999;
        gap: 1rem;
    }
    
    .nav-links.active {
        transform: translateX(0);
        opacity: 1;
        visibility: visible;
    }
    
    .nav-link {
        padding: 1rem 0;
        border-bottom: 1px solid var(--gray-200);
        width: 100%;
    }
    
    .nav-link::after {
        display: none;
    }
    
    .nav-cta {
        margin-left: 0;
        width: 100%;
    }
    
    .lang-switch {
        width: 100%;
        justify-content: center;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .mobile-menu-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(7px, 7px);
    }
    
    .mobile-menu-toggle.active span:nth-child(2) {
        opacity: 0;
    }
    
    .mobile-menu-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -7px);
    }
    
    .hero {
        padding: 8rem 1.5rem 4rem;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-description {
        font-size: 1.125rem;
    }
    
    .hero-stats {
        gap: 2rem;
    }
    
    .section {
        padding: 4rem 1.5rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .features-grid,
    .capabilities-grid {
        grid-template-columns: 1fr;
    }
    
    .cta-title {
        font-size: 2rem;
    }
    
    .cta-description {
        font-size: 1.125rem;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-cta {
        flex-direction: column;
        width: 100%;
    }
    
    .hero-cta .btn {
        width: 100%;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: 1.5rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
    
    .cta-title {
        font-size: 1.75rem;
    }
}

/* ======================
   Animations
   ====================== */

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

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}