External API issue

I am new to jitsi.I am trying to integrate it with my basic HTML page with below code

    <script src="https://meet.jit.si/external_api.js"></script>
        var domain = "meet.jit.si";
        var options = {
            roomName: "CitDemo2020",
            width: '100%',
            height: '100%',
            parentNode: undefined,
            configOverwrite: {},
            interfaceConfigOverwrite: {
                filmStripOnly: true
        var api = new JitsiMeetExternalAPI(domain, options);

It is working fine but the only problem with mobile browser it doesn’t look good even the speaker (who is speaking at any time) is not getting highlighted and not displayed in main video frame.
Videos of both the participants are visible in small frames (boxes) only.