How do I get rid of these vertical dotted lines?

Sure, change this in your css.

.sticky {
border:0px dashed #555555;
padding:10px; }

The border is now 1px.

Or:

.sticky {
border:none;
padding:10px;
}

Also a posibility yes ??

wordpress.com also has its own support forum
https://en.forums.wordpress.com/forum/support

a good idea.