Hi Steve -- You're running into a Template Builder bug that strips out inline CSS after saving the code view of your template. This is a pretty specific bug that comes into play only when the data-e2ma-name class is used in a <td>. We're already working to resolve this bug, and I'll be sure to let you know here when it's fixed.
In the meantime, you can save your template in code view, and then hop over to the HTML view to add that background color.
Can you tell me the name of your account, so I can be sure to log that you ran into this bug?