Bourbon's background-size mixin has been deprecated, and they recommend to use the
official spec.

Bourbon's box-shadow mixin has been deprecated, and they recommend to use the
official spec.

The official border-radius mixins were deprecated and removed in Bourbon 3.0.
https://github.com/thoughtbot/bourbon/pull/95

theming - revised variables and link/button styling to account for edX's registration and login constrast/styling changes

If a course is not started, the course image and title on the dashboard link
to the course about page. Because the LMS course about pages do not exist
(i.e. 404) with the marketing site enabled, we simply do not use a link if
the course has not started.

Now that we are using separate pages for login and registration rather than
modals, clicking the registration button for a course should direct an
unauthenticated user to the registration page, and the user should be enrolled
in the course upon successful registration. Likewise, an unauthenticated user
attempting to unenroll from a course should be directed to the login page and
subsequently unenrolled from the course upon successful login. The enrollment
change service also now uses HTTP status codes rather than JSON to communicate
status to the front end.

lms - cleared document flow for .teacher elements within a course's about view to coincide with Studio's default HTML for the course overview settings field

edx.org - adding in an intermediate disabled state for login/register submit buttons when the form is first processed

edx.org - changed status message UI to be hidden by default (rather than with JS) for the time being for page load/render's sake

edx.org redesign - revised temporary login/register views to fit with design requirements/fixes from marketing team's overall design changes to site's visual theme

lms - revised classes and styling mechanics for login/register forms and added necessary screen-reader mixin for other visually hidden text in those pages