Remove the up and down line behavior

Hi,

I inserted this CSS code to reduce the top margin:

But, every time I refresh the page, the space that was reduced goes down and up.

It looks like it goes to its previous place and comes back to the rectified place.

How to remove this behavior?

---
Also, in the cPanel editor, I got a warning message that says: "Don't use adjoining classes."
Should I ignore it? Because when we don't adjoin them, the...

Remove the up and down line behavior WordPress ...