consitent box and table color and background-color

[data-coder]

Minor changes in the css. Looks better in my opinion.

Note: My first pull request on GitHub, let me know if I'm doing something wrong and feel free to suggest improvements to my commit or reject it :)

A border could be added to every .box, but I took a look at some good Tableau dashboards and the good looking ones do not use border to separate boxes and neither use a different background