Hard to read input fields

[umbernhard]

A lot of the preptool's input fields are hard to see. For instance, if I go to add a party or candidate, the field will get added to the table, but will have a white background with no border, so it blends in perfectly with the background. This may be an OS thing, I'll need to test it in Linux and Windows, but on Mac it can definitely be a big problem. Here are some pictures for examples:

On the candidate's screen, after adding a candidate

The newly added candidate focused

On the party screen, before adding a new party

After adding a new party, unfocused

After adding a new party, focused

[umbernhard]

Interestingly, this isn't really an issue on Windows.