Remove the main from the heading in side panel

![Screenshot 2024-03-31 232253|690x422](upload://izQqHZ0bwPmFeIwNANLZRvT11Pe.png)
![Screenshot 2024-03-31 232323|690x435](upload://QIkWZSmKYCGkfms7fjQSUn12Cl.png)

I want it to look like the second image which is a different theme [Modern Dark Gradient With Green](https://community.getmailspring.com/t/modern-dark-gradients-theme-with-green-accent/1476) 
But the other theme does not work well, so