The app icons (web/mobile/desktop) got all squished together when
they broke to a new line in smaller windows. They now have better
spacing and all break at the same time.
The integration widgets on the homepage had a weird-looking white
border. That border has now been updated to match the better-
looking border on the integrations page.
This commit transitions landing-page.css from the Django pipeline
to being compiled by webpack as landing-page.scss under the
'landing-page' and 'integration' bundles.