your screen is smaller than the page expects. recently, the iNat overseers began testing some new mobile-friendly dynamic layouts for various pages, and you may want to opt into that test. try going into your account settings, and under the Account section, look for a Test Groups section. join the mobile-friendly mode test, and then refresh the page. you should get a new layout that should work better on your small screen.
if you’re not willing to opt into the test or the option isn’t availabe, i think your only other option for now is to decrease the size of the elements on your screen. i’m not sure how Apple handles that sort of setting, but i would expect therre to maybe be a display zoom setting or maybe a display text size setting. alternatively, maybe the browser itself has a zoom setting.