This change updates our main forms CSS definitions to use Ink-defined colors and spacing throughout. This includes several vaguely interrelated pieces: - Fixed up colors throughout, removing hard-coded color codes and #rb-ns-ui.colors variables in favor of Ink CSS variables. - Moved old LESS-based variables into clearly-denoted legacy sections. - Updated field help text to use an ink-provided icon and flexbox-based layout, fixing up some ugly spacing and alignment. - Fixed an issue where opening the inline editor for draft comment replies caused the text to jump horizontally (we apparently had a rule for the horizontal margins get mistakenly deleted?). - Fixed up some existing definitions of CSS variables to use correct type prefixes. Testing Done: - Went through a variety of forms in the admin UI and verified appearance of form fields and fieldsets (both expanded and collapsed). - Verified appearance and functionality of textarea/CodeMirror editors in review request fields, reviews, and replies. - Verified that opening the editor for all inline editable textarea/CodeMirror fields did not cause any visual jumps. - Verified the appearance of <input> and <textarea> elements in other parts of the UI, including review request fields and reviews.