Fixed "Add Sketch to Collection" Popup styling bug on Dark and High Contrast themes

[SundeepChand]

Fixes #1542

I have verified that this pull request:

• has no linting errors (npm run lint)
• is from a uniquely-named feature branch and has been rebased on top of the latest master. (If I was asked to make more changes, I have made sure to rebase onto master then too)
• is descriptively named and links to an issue number, i.e. Fixes #123

[catarak]

Looks good to me! While I was reviewing this, I also added some other minor changes to match the QuickAddList table styling to match the SketchList/CollectionList, by adding a border.