Why does header shrink after getting vue js build?

It was a very silly thing. In localhost, my header component looks quite normal, but after rendering everything on the page stays in the same design, the header gets smaller.

I’m working on netflix clone project, why is my header design getting smaller while everything is building properly on the page?

I did not interfere with the header in any way as javascript. Why did such an event happen to me when I was only standing as a component?