* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-blue: #4285F4;
    --primary-red: #EA4335;
    --primary-yellow: #FBBC04;
    --primary-green: #34A853;
    --text-primary: #202124;
    --text-secondary: #5F6368;
    --border-color: #DADCE0;
    --bg-light: #F8F9FA;
    --bg-white: #FFFFFF;
    --shadow-sm: 0 1px 2px 0 rgba(60,64,67,0.3), 0 1px 3px 1px rgba(60,64,67,0.15);
    --shadow-md: 0 1px 3px 0 rgba(60,64,67,0.3), 0 4px 8px 3px rgba(60,64,67,0.15);
    --shadow-lg: 0 2px 6px 2px rgba(60,64,67,0.15), 0 8px 24px 4px rgba(60,64,67,0.15);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    color: var(--text-primary);
    line-height: 1.6;
    background: var(--bg-white);
}

.header {
    background: var(--bg-white);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.2s;
}

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

.nav-download {
    background: var(--primary-blue);
    color: white !important;
    padding: 0.5rem 1.25rem;
    border-radius: 4px;
    transition: background 0.2s;
}

.nav-download:hover {
    background: #1a73e8;
}

.hero {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 2rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-content h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--primary-blue), var(--primary-red));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
}

.btn-primary {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--primary-blue);
    color: white;
    padding: 1rem 2rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    font-size: 1.125rem;
    transition: all 0.2s;
    box-shadow: var(--shadow-sm);
    border: none;
    cursor: pointer;
}

.btn-primary:hover {
    background: #1a73e8;
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.btn-secondary {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--bg-white);
    color: var(--primary-blue);
    padding: 1rem 2rem;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    font-size: 1.125rem;
    border: 2px solid var(--primary-blue);
    transition: all 0.2s;
}

.btn-secondary:hover {
    background: var(--bg-light);
}

.platform-info {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.features {
    background: var(--bg-light);
    padding: 5rem 2rem;
}

.features h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.features-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s;
}

.feature-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
}

.feature-icon {
    margin-bottom: 1.5rem;
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.8;
}

.security {
    padding: 5rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.security h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
}

.security-features {
    display: grid;
    gap: 2rem;
}

.security-item {
    display: flex;
    gap: 1.5rem;
    padding: 1.5rem;
    background: var(--bg-light);
    border-radius: 8px;
    transition: all 0.2s;
}

.security-item:hover {
    background: #e8f0fe;
}

.security-item h4 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.security-item p {
    color: var(--text-secondary);
}

.faq {
    background: var(--bg-light);
    padding: 5rem 2rem;
}

.faq h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
}

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

.faq-item {
    background: var(--bg-white);
    margin-bottom: 1rem;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.faq-question {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
    text-align: left;
    transition: background 0.2s;
}

.faq-question:hover {
    background: var(--bg-light);
}

.faq-question svg {
    flex-shrink: 0;
    transition: transform 0.3s;
}

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

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out;
}

.faq-item.active .faq-answer {
    max-height: 1000px;
    transition: max-height 0.5s ease-in;
}

.faq-answer p, .faq-answer ul, .faq-answer ol {
    padding: 0 1.5rem 1.5rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

.faq-answer ul, .faq-answer ol {
    padding-left: 3rem;
}

.faq-answer li {
    margin-bottom: 0.5rem;
}

.faq-answer strong {
    color: var(--text-primary);
}

.cta {
    padding: 5rem 2rem;
    background: linear-gradient(135deg, var(--primary-blue), var(--primary-red));
}

.cta-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    color: white;
}

.cta-content h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.cta-content p {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.95;
}

.btn-large {
    padding: 1.25rem 2.5rem;
    font-size: 1.25rem;
}

.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 2rem 1.5rem;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h4 {
    margin-bottom: 1rem;
    font-size: 1.125rem;
}

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

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

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.2s;
}

.footer-section a:hover {
    color: white;
}

.footer-bottom {
    max-width: 1200px;
    margin: 0 auto;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    text-align: center;
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.875rem;
}

.download-hero {
    background: linear-gradient(135deg, #e8f0fe 0%, #fce8e6 100%);
    padding: 4rem 2rem;
    text-align: center;
}

.download-hero-content h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.download-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.download-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 800px;
    margin: 0 auto;
}

.download-platforms {
    max-width: 1200px;
    margin: 0 auto;
    padding: 4rem 2rem;
}

.platform-featured {
    background: linear-gradient(135deg, #e8f0fe 0%, #fff 100%);
    border: 2px solid var(--primary-blue);
    border-radius: 16px;
    padding: 3rem;
    margin-bottom: 4rem;
    position: relative;
    box-shadow: var(--shadow-lg);
}

.platform-badge {
    position: absolute;
    top: -12px;
    right: 2rem;
    background: var(--primary-red);
    color: white;
    padding: 0.5rem 1.5rem;
    border-radius: 20px;
    font-weight: 600;
    font-size: 0.875rem;
}

.platform-icon {
    text-align: center;
    margin-bottom: 2rem;
}

.platform-featured h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.platform-version {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.125rem;
    margin-bottom: 1.5rem;
}

.platform-desc {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.125rem;
    line-height: 1.8;
    max-width: 800px;
    margin: 0 auto 2rem;
}

.platform-features {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 2rem;
}

.feature-tag {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: white;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
    box-shadow: var(--shadow-sm);
}

.btn-download-primary {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    background: var(--primary-blue);
    color: white;
    padding: 1.25rem 3rem;
    border-radius: 8px;
    font-weight: 600;
    font-size: 1.25rem;
    border: none;
    cursor: pointer;
    margin: 0 auto;
    transition: all 0.2s;
    box-shadow: var(--shadow-md);
}

.btn-download-primary:hover:not(:disabled) {
    background: #1a73e8;
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.btn-download-primary:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

.download-info {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-top: 1rem;
}

.platforms-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.platform-card {
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    text-align: center;
    transition: all 0.3s;
    box-shadow: var(--shadow-sm);
}

.platform-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
    border-color: var(--primary-blue);
}

.platform-icon-small {
    margin-bottom: 1.5rem;
}

.platform-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.platform-card > p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-size: 0.875rem;
}

.platform-small-desc {
    color: var(--text-secondary);
    font-size: 0.875rem;
    line-height: 1.6;
    margin-bottom: 1.5rem;
    min-height: 60px;
}

.btn-download-secondary {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    background: var(--bg-white);
    color: var(--primary-blue);
    padding: 0.875rem 1.5rem;
    border-radius: 6px;
    font-weight: 600;
    border: 2px solid var(--primary-blue);
    cursor: pointer;
    transition: all 0.2s;
    width: 100%;
}

.btn-download-secondary:hover:not(:disabled) {
    background: var(--primary-blue);
    color: white;
}

.btn-download-secondary:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

.installation-guide {
    background: var(--bg-light);
    padding: 5rem 2rem;
}

.installation-guide h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
}

.guide-steps {
    max-width: 900px;
    margin: 0 auto;
    display: grid;
    gap: 2rem;
}

.guide-step {
    display: flex;
    gap: 2rem;
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
}

.step-number {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background: var(--primary-blue);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 700;
}

.step-content h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.step-content p {
    color: var(--text-secondary);
    line-height: 1.8;
}

.system-requirements {
    padding: 5rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.system-requirements h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
}

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

.requirement-card {
    background: var(--bg-light);
    padding: 2rem;
    border-radius: 12px;
    border-left: 4px solid var(--primary-blue);
}

.requirement-card h3 {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.requirement-card ul {
    list-style: none;
}

.requirement-card li {
    padding: 0.5rem 0;
    color: var(--text-secondary);
    padding-left: 1.5rem;
    position: relative;
}

.requirement-card li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--primary-blue);
    font-weight: bold;
}

.download-faq {
    background: var(--bg-light);
    padding: 5rem 2rem;
}

.download-faq h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
}

.download-cta {
    padding: 5rem 2rem;
    background: linear-gradient(135deg, #1a73e8 0%, var(--primary-blue) 100%);
}

.download-cta .cta-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    color: white;
}

.download-cta h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.download-cta p {
    font-size: 1.25rem;
    margin-bottom: 2rem;
}

.btn-download-large {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    background: white;
    color: var(--primary-blue);
    padding: 1.25rem 3rem;
    border-radius: 8px;
    font-weight: 600;
    font-size: 1.25rem;
    border: none;
    cursor: pointer;
    transition: all 0.2s;
    box-shadow: var(--shadow-lg);
}

.btn-download-large:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(0,0,0,0.2);
}

.btn-download-large:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

.download-terms {
    margin-top: 1rem;
    font-size: 0.875rem;
    opacity: 0.9;
}

.spinner {
    animation: spin 1s linear infinite;
    margin-right: 0.5rem;
}

@keyframes spin {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

@media (max-width: 768px) {
    .hero {
        grid-template-columns: 1fr;
        gap: 2rem;
        padding: 2rem 1rem;
    }

    .hero-content h1 {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1.25rem;
    }

    .hero-buttons {
        flex-direction: column;
    }

    .hero-image svg {
        width: 100%;
        height: auto;
    }

    .nav-menu {
        gap: 1rem;
        font-size: 0.875rem;
    }

    .features h2, .security h2, .faq h2, .cta h2, .download-hero h1, .installation-guide h2, .system-requirements h2, .download-faq h2 {
        font-size: 2rem;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .platform-featured {
        padding: 2rem 1.5rem;
    }

    .platform-featured h2 {
        font-size: 2rem;
    }

    .platforms-grid {
        grid-template-columns: 1fr;
    }

    .guide-step {
        flex-direction: column;
        gap: 1rem;
    }

    .requirements-grid {
        grid-template-columns: 1fr;
    }

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