For my website, the content scales its size based window size, how to make it so that at a certain point it stops scaling and just adds a scroll bar?

Many of the divs and images on the page are sized based on the size of the window, but when the window gets too small everything gets messed up. I am trying to figure out how to use css to make it so that once the window reaches some minimum size, the content stops scaling and overflows with a horizontal scroll bar. I hope that makes sense.