tool bar audio not working properly in mobile

Hi,

We are creating a course presentation including some audios and we think that there is an issue on the presentation of the audio player.

The thing is that the audio player is not appering ok in mobiles, the half of the player is hidden. (we take care that is on the front)

The first workaround is just increase the size of the bar, but when we try to do this, a black background appear in the player tool. 

Please see the photo attch to figure out the problem.

Best regards,

Sebastian