How to fix the pop-up menu with a large screen width?

Question

JavaScript

There is a quite viable menu, but if the screen width is more than 1770px, it is required to make it open by default with the ability to close it by clicking on the cross. I implemented this, but the problem is, when you first open the page on a large screen and when you follow the links, the menu slides out to the left every time. How to fix it rigidly so that it does not float back and forth?