Custom screen size choices

Would it be possible to add a custom size option that we could choose the size ourselves?

For instance, on one of my sites, I’d like to choose the screen size of 1000px. This is because:

(1) The 1024px dropdown choice makes tinynav load on 1024×768 desktop monitors and I would like to set it to only work on sizes smaller than that.

(2) The 800px dropdown choice is too small as it means my menu is on two lines between 1000px and 800px.

Or can you give me some other way to set my own screen width?

https://wordpress.org/plugins/tinynav/