Primary Nav changes size when switching from one category to another

Hi there,

I noted that when I move from one part of the menu on the main Nave to another -- say from Home to Review, for example -- the Nav's menu items or the frame would jerk around, changing their font size, or type, or width, or height, for a brief moment. How can I stop that from happening, and keep the Nav's content and shape persistent?

https://dongknows.com/

Thanks,

-Dong.