Standardize font sizes and heading tags (<h1>-<h6>) to be more
consistent across the site.
Changes:
* Introduce font size CSS variables and start replacing hardcoded font
sizes with standard sizes.
* Change header tags to use only one <h1> per page. One <h1> per page is
recommended for SEO purposes. Usually this is for the page title, like
in forum threads or wiki pages.
* Standardize on <h2> for section headers in sidebars and <h3> for
smaller subsection headers. Don't use <h4>-<h6>.
* In DText, make h1-h4 headers all the same size. Standard wiki style is
to ignore h1-h3 and start at h4.
* In DText, make h4-h6 the same size as the h1-h3 tags outside of DText.
* In the tag list, change the <h1> and <h2> tag category headers to <h3>.
* Make usernames in comments and forum posts smaller. Also change the
<h4> tag for the commenter name to <div class="author-name">.
* Make the tag list, paginator, and nav menu smaller on mobile.
* Change h1#app-name-header to a#app-name-header.
Bug: extremely long sources cause the Tags column to become extremely
wide. Caused by the source link not having the word-break property set.
Fix: use post_source_tag, which lets the `a[rel=external] { word-break: break-word; }`
rule take effect.
Example: https://danbooru.donmai.us/post_versions?search%5Bpost_id%5D=3809742
Side effects:
* The data-current-user-is-voter <body> attribute has been removed.
* {{upvote:self}} no longer works. {{upvote:<name>}} should be used instead.
Change it so that when a post contains bad tags, the tags themselves are
highlighted rather than the entire post.
This also adds a data-tag-name attribute to tags in tag lists.
Rework how posts are displayed in the modqueue:
* Rearrange post info to take up less space and to be consistent with
how posts are shown on the comments index.
* Reduce font size of approve / reject options.
* Reduce empty space around thumbnails and between posts.
* Add size info beneath thumbnails.
* Allow voting on posts.
* Use PostPresenter.preview to standardize rendering of thumbnails. This
adds parent/child borders, tooltips, and data attributes.
* Add options for changing the order of the modqueue (newest first,
oldest first, highest scoring first, lowest scoring first).
* Change the default order from oldest posts first to most recently
flagged or uploaded posts first.
* Add an order:modqueue metatag to order by most recently flagged or
uploaded in standard searches.
Add a sidebar to the modqueue page that shows the following information:
* Number of pending and flagged posts.
* Number of posts disapproved for poor quality or breaking rules.
* Top uploaders in the queue.
* Top artist, copyright, and character tags in the queue.
