Background image is being set to white

When I publish a post that comes through ucan-post, it’s automatically adding some formatting that doesn’t mesh with the rest of my site. The main culprit is background color. It looks like it’s automatically added a background-color: #ffffff style around each block of text that a user submits. This leaves the user’s post surrounded by a white text box, when the background of my site is not white.

Here is an example of what I’m talking about: https://www.vcize.com/images/ucanpost-white.png

Notice the white box surrounding the text of the post. I don’t want that there. How can I eliminate this without having to go through every user post and manually strip out the attribute?

Also, is there a way to set the default font/size in the user’s editor to match the font on my site? It looks really unnatural with all the user posts being a different font than the rest of the site.