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.
* Add Discord, Twitter, and Github links to site footer.
* Remove "Desktop mode" and "Keyboard shortcuts" links from footer.
Users can use the desktop site option in their browser to switch
between desktop and mobile mode.
* Remove git hash from footer. Users can hover over the Github logo to
see the hash instead.
Bug: if a post had a large number of child posts, the child post preview
box would expand beyond the width of the screen.
Setting `min-width: 0` makes the flexbox column shrink instead of
expand.
* Switch /static/keyboard_shortcuts from float-based layout to flexbox.
* Switch /moderator/dashboard from float-based layout to flexbox.
* Remove various .clearfix, `clear: both` rules.
* Remove dead .quick-mod rule.
* Reduce size of buttons, form inputs, site menu items, paginator, and
sidebar text.
* Remove various dead rules (nonexistent selectors, rules overriden by
other rules, rules that were otherwise redundant or did nothing).
* Increase page margin size.
* Fix notes being mispositioned (caused by `#image { margin-top: 5px }` rule).
* Remove `list-style-type: none` rules (this is the default).
* Add `list-bulleted` and `list-inline` utility classes.
* Wrap terms of service and user deletion pages in dtext `.prose` class
so we don't have to redefine basic list styles on these pages.
* Remove .ui-corner-all, .ui-state-highlight, .ui-state-error classes
from notice boxes.
* Use .notice, .notice-info, .notice-error classes instead.
* Replace <p> elements in notices with <div>'s so that we don't have to
work around the `margin-bottom: 1em` from <p> elements.
* Replace <h1> elements in notices with <h2>.
* Standardize info notices to use the same shade of light yellow in the
light theme.
Fixes the search button wrapping to the next line in Firefox. Also fixes
the search box to be full width with no gap between the search box and
the search button.
* Consolidate blacklist css in one file.
* blacklist box: fix tag colors not dimming on hover.
* blacklist box: allow middle clicking on tags to open in new tab.
* /wiki_pages: move blacklist controls to top of tag sidebar.
* /wiki_pages: fix missing "disable all" / "re-enable all" buttons.
