President Evil

mmm I will fix it in next update 
for now just add this to custom.css 
.ipsWidget .ipsTable th { background: inherit; }  
Thanks.

Hello,
This color setting is in Front-End colors tabs, named Area background but im unsure if the white background comes from that it might be from whatever that app/plugin widget you're using, i cant check without a link tho 
This is just an svg line separator theres no settings to remove, but you can simple remove it in globalTemplate 
search by this css class and remove the line 
sec-sepTop  
maybe in next version  if you still want to do something like this maybe try to add the below css to custom.css,  i posted for someone else he wanted something similar to what you ask
 
Is this setting enabled on your side?