Thanks for the quick response, those both worked. For the header, the font size to maintain a static appearance is actually 16. HOwever, there is still one aspect that changes on scroll. The font size is static now, but the navigation links move up the screen about 3 or 4 pixels when you start scrolling.
Below is a link to the test bed I am using
https://help.colesoft.com/new/education/
Any help is appreciated, i am already impressed by how well you support this theme.
