* 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.
* Switch from flat greys to cool blue greys.
* Define colors with HSLuv (https://www.hsluv.org) so that each band of
colors is perceptually uniform (has the same brightness and contrast).
* Adjust platinum user color.
* Change alert notices to grey with blue border.
* Add padding to text <input> elements so that the text isn't right next
to the edge.
* Style <button> and <input> elements explicitly instead of relying on browser defaults.
* Style jquery ui buttons the same way as regular buttons.
* Add color variables so we can restyle form inputs in dark mode.
* Standardize the upload widget background colors (light green for success,
light red for error).
* Move the progress bar to the bottom of the upload widget.
* Change the progress bar color to blue.
* Hide the "drag and drop a file here" message after a file has
already been uploaded.
Standardize background colors to light green or light red in several places:
* Modqueue positive/negative score backgrounds.
* Modqueue quality/sample warning backgrounds.
* User feedback positive/negative backgrounds.
* Ban expired/unexpired backgrounds.
* Flag resolved/unresolved backgrounds (removed; resolved flags no
longer have a grey background because of inconsistencies in what
resolved means).
Fineprint text was variously styled with `.info`, `.tn`, `.hint`, or
`.cost-footnote` css classes. Standardize on `.fineprint` instead. Use
`.hint` only for form hints and `.tn` only for <tn> tags in translation
notes.
Incidentally changes the font size of form hints to 0.8em (was 0.7em)
and the color of fineprint to #888 (was #AAA or #666).
Position <span class="hint"> elements to the right of normal <input>
elements and underneath <textarea> elements. Fixes form hints being
badly positioned on some pages.
