Safari css stops working on larger screen

I have inherited a web page with a large amount of CSS.

I’m working on a Mac Book Pro laptop connected to a 29" monitor.

In Safari on the laptop screen the page and the css work as expected.

If I drag the Safari window on to the monitor the CSS stops working.

I’m completely baffled. What could be causing this in the CSS, what should I look for.

“Stops working” as in: you see HTML without any make-up? Or with errors, or what you think are errors?

I see the html with some styling but not all

Hi, do you have a website where we can see this recreated? Have you validated your HTML and CSS?

Hi, ttmt.

Your descriptions are a bit vague. We could really use a link to the web site so we can see the problem and code. Does the problem appear in browsers other than Safari Mac?

Sorry I’m working locally at the moment, I can’t move it. The problem only happens in Safari

Well without some test page c ode, we are unable to do anything. Can you give us enough HTML/CSS to recreate it on our end? We are in the dark here :).

I know it’s vague, I’ll try and recreate the problem and post.