Improve suggester color and width styles

* Removes the blue color from the items in the suggester. The same is done in core/resources/src/mediawiki/mediawiki.searchSuggest.css.
* Adds a basic min-width to make sure click-regions always have a decent size. The `8em` is copied from core/resources/lib/oojs-ui/oojs-ui.css.
* Reverts ~~#84~~ #83. It became obsolete the moment ~~#83~~ #84 finally got merged after two weeks.

[Bug: 66435](https://bugzilla.wikimedia.org/show_bug.cgi?id=66435)