WebUI Dark Mode: fix up empty list message in light/dark

Screenshots: https://imgur.com/a/EwqTzly

R=hcarmona@chromium.org
BUG=936524

Change-Id: I5ed3a43dc4273c1179eddca56a8138cf394c10a6
Reviewed-on: https://chromium-review.googlesource.com/c/1496246
Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Commit-Queue: Dan Beam <dbeam@chromium.org>
Auto-Submit: Dan Beam <dbeam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636676}
1 file changed