CSS File Manipulation

[AdrianGray]

I am looking for guidance as to how best to remove a selector and its declaration from a CSS file. I need to remove the following section from the attached file. I can't see an easy way to edit a text file without recreating it, deleting the old one, then renaming the new one back.

As this declarations for the other selectors contain unique values per site, I am unable to just replace the file.

Thanks in advance, Adrian.

.login_form_footer_bg {
background-color: #asdfasdfs !important;
}

[SteveDude]

Have you tried Replace String?

What I've done with a couple of installs is create the complete data file whatever it may be that requires no changes, install it using the Native Engine and then appended the part I did want to change to that file.