Clean up taxonomy css

From https://gist.github.com/3006391

csslint: There are 3 problems in core/modules/taxonomy/taxonomy.css.

taxonomy.css
1: warning at line 2, col 1
Element (tr.taxonomy-term-preview) is overqualified, just use .taxonomy-term-preview without element name.
tr.taxonomy-term-preview {

taxonomy.css
2: warning at line 5, col 1
Element (tr.taxonomy-term-divider-top) is overqualified, just use .taxonomy-term-divider-top without element name.
tr.taxonomy-term-divider-top {

taxonomy.css
3: warning at line 8, col 1
Element (tr.taxonomy-term-divider-bottom) is overqualified, just use .taxonomy-term-divider-bottom without element name.
tr.taxonomy-term-divider-bottom {

Here's a patch blindly implementing csslint suggested changes.

rob@Computron /var/www/drupal/8 $ node ../../csslint/release/npm/cli.js core/modules/taxonomy

csslint: No errors in core/modules/taxonomy/taxonomy.css.

I really need someone who actually knows what's going on here to review the patch and confirm the changes here are good, and why. I don't mind committing a lot of these, but I want to understand what's happening, and everything here seems like it's just running it through a tool and saying "ok."

CSSLint is a tool to test and clean up your CSS. You can read about what it helps with over in the Rules. Parsing the CSS with this will help improve browser render performance, and help clean up issues that would otherwise be missed.

Essentially what we're doing here is:

1. Clean up the CSS with CSSLint (add classes if needed)
2. Confirm in the browser that the user interface is not affected with the change
3. Run CSSLint again to confirm the CSS is now clean
4. Upload the patch
5. Test the patch
6. RTBC said patch
7. Dance

Yes, I understand the mechanics of all that. :P My question is, What are these specific CSS changes doing, and why is it good?

This particular issue cleans up overqualified elements.

Actually, it is duplicated (a part of) HTML5 cleanup. Compare to HTML5 CLEAN UP, it provided a standard tool to check the problem. I do suggest to close all duplicated issues: http://drupal.org/node/1190252#comment-6171090.

Thanks; so according to the referenced link this is a small performance improvement by having a less-specific class selector, because it doesn't need to find the element first, then find the specific class.

I'm not sure what #8 means. But this seems simple enough.

Committed and pushed to 8.x. Thanks!

Avoiding overqualified elements is only being suggested in order to reduce filesize, afaik. I don't think we should just implement every case where csslint is suggesting it.

At least in this case, I don't see anyone re-using the same classes on other html elements so I think we can safely asume it's ok to not specify the element in the css selector.

We could however run into trouble if the class names are more generic and could be perhaps used elsewhere by people on their own sites. In these cases we should keep the "overqualified elements" selectors. Of course, how to determain which is which is a different story, I suggest we use common sense and a bit of hope =)