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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    min-height: 100vh;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    color: #2d3748;
    line-height: 1.6;
}

/* Header Navigation */
header {
    max-width: 800px;
    margin: 0 auto;
    padding: 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-nav {
    display: flex;
    gap: 24px;
    align-items: center;
}

.header-nav a {
    color: #2d3748;
    text-decoration: none;
    font-weight: 500;
    font-size: 0.95rem;
    transition: opacity 0.2s;
}

.header-nav a:hover {
    opacity: 0.7;
}

.header-nav a.current {
    opacity: 1;
    font-weight: 600;
    color: #667eea;
}

/* Container */
.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 60px 24px;
}

/* App Icon */
.app-icon {
    filter: drop-shadow(0 12px 40px rgba(0,0,0,0.15)) drop-shadow(0 4px 12px rgba(0,0,0,0.1));
}

/* Footer */
footer {
    margin-top: 64px;
    text-align: center;
    opacity: 0.7;
    font-size: 0.9rem;
}

footer a { 
    color: #667eea; 
    text-decoration: none;
    margin: 0 8px;
}

footer a:hover {
    text-decoration: underline;
}

.footer-links {
    margin-top: 8px;
}

/* App Store Badge */
.app-store-badge {
    display: inline-block;
    width: 180px;
    height: 60px;
    text-decoration: none;
    transition: transform 0.2s, opacity 0.2s;
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.app-store-badge:hover {
    transform: translateY(-2px);
    opacity: 0.9;
    box-shadow: 0 6px 16px rgba(0,0,0,0.3);
}

.app-store-badge img {
    width: 100%;
    height: 100%;
    display: block;
}

.app-store-badge .badge-dark {
    display: none;
}

.app-store-badge .badge-light {
    display: block;
}

/* Dark Mode */
@media (prefers-color-scheme: dark) {
    body {
        background: linear-gradient(135deg, #1a202c 0%, #2d3748 100%);
        color: #f7fafc;
    }
    
    .app-store-badge {
        box-shadow: 0 4px 12px rgba(0,0,0,0.4);
    }
    
    .app-store-badge:hover {
        box-shadow: 0 6px 16px rgba(0,0,0,0.5);
    }
    
    .app-store-badge .badge-dark {
        display: block;
    }
    
    .app-store-badge .badge-light {
        display: none;
    }
    
    footer a { 
        color: #90cdf4; 
    }
    
    .header-nav a {
        color: #f7fafc;
    }
    
    .header-nav a.current {
        color: #90cdf4;
    }
    
    .app-icon {
        filter: drop-shadow(0 12px 40px rgba(0,0,0,0.4)) drop-shadow(0 4px 12px rgba(0,0,0,0.3));
    }
}

/* Responsive */
@media (max-width: 600px) {
    header {
        padding: 16px;
    }
    
    .header-nav {
        gap: 16px;
        font-size: 0.9rem;
    }
}