Improve styling and modernize the template for Change Form pages.
Review Request #10850 — Created Jan. 23, 2020 and submitted
This change completes much of the re-styling and re-implementation of
the administration UI's Change Form pages. It adds specialized styling
for some Django admin form widgets to help them better fit into our
pages and updates existing styles to fix up some small layout issues.
It also updates the main change form template to remove legacy cruft and
to take advantage of our modern CSS components. As part of this template
rewrite, we no longer pull in the Django admin UI form CSS. An upcoming
change will scrap the remainder of the Django styles and overrides,
paving the way for Django 1.11.
Tested every change form for every model in desktop and mobile modes,
making sure everything rendered as expected.