Main Calendar Border

In this screenshot you can see the main calendar, its the one in the navigation bar that goes to the calendar page, and in this screenshot you can see some of the days of the week, I would like to add a small border around each calendar day so its easy to differentiate where one day begins and ends. The way it now with no border its hard to tell where each day block begins and ends. Thanks, I'm using Invision.

Perfect, thank you so much..

Edit: one last think on the calendar, how to I make this ones day of the month highlight too with a font color and background?

Ok no problem. I was able to make the day go bold though, just no changing the color or background. So that's good enough,, thanks