Hello @Insider! Happy to see you here! 

You can change the color by editing the design of your Side tab embedding option. Follow the steps below:
1. Go to the "Share" panel and under the "Embed in a web page" click in "Side tab".
2. Select "Design" and change its button color. 

The color of the text will be set automatically by the tool. It's the same behavior as the normal form. If the button is dark, the color is white and if the button is clear, then the color is black. Check it out in the image below. 

I hope I was able to help! Let me know if you have any other questions. We'd be happy to help! 

Is there any guidance that can be provided to specify the text color rather thant to have it as an automatic styling rule?

I would imagine that this is quite a high priority when considering branding.

Hi @Insider Changing the text color isn’t currently a feature we offer, but you can add your feedback for it in the thread below.