refer this video.
https://vimeo.com/144384425
I think this issue occur by this code
wp-core-ui.css line 12.
It disappeared when i deleted this selector's height,width,padding,margin.
We checked this issue .thanks for sharing the fix as well . Thanking you also for reporting this .
We will get it fixed in the next update of wplms .
For other users please remove the line 12 form the wp-core-ui.css file in wp-content/plugins/wplms-front-end/css folder .