I am creating a responsive email with SFMC content builder. I want to place a button in the center of the email with a white background. The template content background color is purple and I have made the button background color white within the block settings for the button. It displays fine on desktop (http://i.imgur.com/V8iYARX.png) however when viewing the email on mobile it reverts to this (http://i.imgur.com/c4DG04D.png) where the template content background color is visible.
The table for the button doesn't seem to be expanding to the full width of the container. I have tried testing a full width table using just the html widget but the same thing occurs. I think it must be something that SFMC adds when using the content builder. How can I achieve this?