manifest.json

{
    "name": "Final Countdown",
    "short_name": "Final countdown",
    "id": "/",
    "start_url": "/",
    "display": "standalone",
    "background_color": "#182635",
    "theme_color": "#031c36",
    "orientation": "portrait-primary",
    "icons" : [
        {
            "src": "/img/icons/favicon.png",
            "type": "image/png",
            "sizes": "32x32"
        },
        {
            "src": "/img/icons/chrome192.png",
            "type": "image/png",
            "sizes": "192x192"
        },
        {
            "src": "/img/icons/chrome512.png",
            "type": "image/png",
            "sizes": "512x512"
        },
        {
            "src": "/img/icons/maskable_icon.png",
            "sizes": "192x192",
            "type": "image/png",
            "purpose": "maskable" 
          }
    ]
}