the website changes on the pc.
When you start it is a fullscreen site, if you want to work on it, the website is only about 1200 pixels wide. Can you help me
So it should be a full-width website or a boxed one?
Please, turn off all of the plugins, refresh your cache, and check if the problem persists.
Moreover, if you are using a child theme, switch to parent, and recheck it.