Basically: browsers started scaling pixel sizes years ago, so if you set the width of the page as a pixel size it will scale when you zoom the page. If you use sizes relative to the size of the text (ems or rems) to set the widths of containers, then those will scale when you increase the text size.
Developers can turn zooming off on mobile devices by specifying a fixed viewport which obviously upsets a large subset of people. (But then you potentially have the pinch gesture to yourself and it isn't intercepted by the system, but I digress..)
Alternatively percentage based and max-width css can be used on containers and then you can probably start to get the behaviour you're looking for. I'm not 100% sure if browsers will scale max-width. You can probably set pixel widths on containers and use percentage based sizes for fonts, but then a) you're assuming the default font size is 16px forever and b) the results are still going to depend on whether the browser scales text or zooms the entire page.
In this website's case it probably wouldn't be very helpful if the text scaled up without the design going wider, though. Maybe one or two steps but at a point the main column width gets ridiculously narrow.
Oh and obviously you can just never give containers widths, but then you probably get that html 1.0 look where text just goes all the way from one edge of the screen to the other.
I don't think it really is a solvable problem in a way that will make everyone happy all the time.
Developers can turn zooming off on mobile devices by specifying a fixed viewport which obviously upsets a large subset of people. (But then you potentially have the pinch gesture to yourself and it isn't intercepted by the system, but I digress..)
Alternatively percentage based and max-width css can be used on containers and then you can probably start to get the behaviour you're looking for. I'm not 100% sure if browsers will scale max-width. You can probably set pixel widths on containers and use percentage based sizes for fonts, but then a) you're assuming the default font size is 16px forever and b) the results are still going to depend on whether the browser scales text or zooms the entire page.
In this website's case it probably wouldn't be very helpful if the text scaled up without the design going wider, though. Maybe one or two steps but at a point the main column width gets ridiculously narrow.
Oh and obviously you can just never give containers widths, but then you probably get that html 1.0 look where text just goes all the way from one edge of the screen to the other.
I don't think it really is a solvable problem in a way that will make everyone happy all the time.