Can Background Color of Tabs Be Changed?

[McKinneyPatrick_PA]

One of our users had a question about Dashboard apps hosted in ArcGIS Online.  The app they are creating has Tabs that separate the main content. 

They wanted to know if the background color of these tabs can be changed?

I completed some initial testing, and it does not appear this is possible.  Can anyone confirm whether or not this is a feature that can be modified?

I have provided an image for context. I appreciate any assistance that is provided.