The slider "jumps" on page load/refresh. What's the matter?

Question

css

Good day to all!
I put a slider on the site with my own handles. Everything would be fine, but that's just the slider, when loading and updating the page, it multiplies to the full screen, and only then rises to its original place. How to solve this problem?
Css1
Css2
I know that you have a serious site here, you can write that I'm down if this problem is very good. easy to solve.

Answer 1

Hide the slider until it is initialized, and then show it.

Answer 2

this is normal, scripts are not instantly interpreted.