cal.pub0.org/apps/web/public/browserconfig.xml

<?xml version="1.0" encoding="utf-8"?>
<browserconfig>
    <msapplication>
        <tile>
            <square150x150logo src="/api/logo?type=mstile"/>
            <TileColor>#ff0000</TileColor>
        </tile>
    </msapplication>
</browserconfig>