Header height changes with different windows width

Hi,
First of all thanks for the great job, I have always been pleased with the support here :)

Now, my site header area height changes when the window size goes below a certain size. This is out of step with the menu transition from desktop to mobile version button.
The order from largest to smallest window size is -> menu changes to mobile mode -> header height increases.
This causes my logo to be cropped in the larger window sizes.

Thanks for the help!