Modify height of a header and text vertical center

Hi everybody!
I’m currently using the flexboxes but I want to reduice the height of the header of each box. My purpose is that the height of the boxes is the height of the text. So I tryed to change the height manually with the property “height:25” but my problem is that when I set a height the text is not vertically centered. How can I change this?

My code is here:
https://webix.com/snippet/3112f013

Thanks in advance!

You can assign a css class to the header, and define the necessary line-height through CSS

Check https://webix.com/snippet/747d0c06

Nice ! Thanks for your answer!