overlay on mobile version

i have a problem with the plugin on mobile , there’s an overlay cover the whole screen , Please fix that problem

here’s screenshot
https://s17.postimg.org/di5bmb3yn/Screenshot_2015_12_26_07_55_12.png

and here’s my website
https://www.beassistance.com

https://www.ads-software.com/plugins/tidio-live-chat/