Remove "!important" from code class CSS rule

[avivace]

to allow style overriding

Fixes #1552

[ehuss]

Hm, checking the git history, it looks like this was intentionally added in #1062 to resolve #1061. If both can be resolved, that would be great, but otherwise I don't think it would be good to break the ACE editor.

[YJDoc2]

Hey, I think setting

.ace_editor {
    line-height: 2;
}

would resolve this issues, while removing the !important tag : see node-red/node-red#2104 and ajaxorg/ace#4000 (comment) .