If you find that the color of a snippet has changed for some reason, it is likely that it has changed due to a user selecting a color in the color picker for a different email or landing page.
As an example, the background color for your emails and landing pages in a campaign are set in a CSS document, and are shared between all emails and landing pages.
If you use the color picker feature, and say you select a field called 'Background' and set it to black, what does this do?
What will happen is a CSS class titled .background will have black assigned to it. Thereafter, any component of your email or landing page that has the .background CSS class applied to it, will have a black back ground.
Remember, the color picker will change the color of the field you choose for ALL emails and landing pages in that campaign