Custom CSS for buttons - problem controlling font size

I apologize if this is due to my lack of knowledge of CSS, I am very much a beginner

I want to use a button as my group name so I can have a refresh option without taking additional display space. All good but now I need to increase the button font size to match the group name font. I define a CSS class to left justify and enlarge the font, and set it on the button definition. This technique works for me with Text display widgets. However while the button text is left justified, the font is unchanged.

Examining the style inheritance for the button text I see

and further down

My controls are present, but are not being used - even though they are tagged 'Important'
- Initially I had only the font-size control, not --v-btn-size. Neither work

My controls do work if the 'default' controls are not present
... the display I get

... if default font-size is disabled the custom class font size is used

... if default --v-btn-size is disabled my --v-btn-size is used