I’ve had this issue before with 2.1.4 or Cornerstone and it seemed to be sorted, however i’ve just noticed it’s either still happening or has returned in a recent update.
The default CSS for sections and elements is overriding the CSS that should be generated by cornerstone using the editor.
So for a section #cs-content .x-section {padding:45px 0;} is overriding the generated CSS .el1.x-section {padding:0px;}
I was told before to use a V1 section instead of a V2 and that should fix it, but that was back in November last year and surely should have been fixed by now?
Cheers