Created attachment 462284 [details] Safari inspector Elements tab: the DOM column is too narrow below a certain inspector width. There it's overlapped by the Styles column, which should be stacked like Chrome below a certain size threshold (<700px for the inspector). Attached Safari and Chrome screenshots.
Created attachment 462285 [details] Chrome dev tools
<rdar://problem/100119346>
*** This bug has been marked as a duplicate of bug 259391 ***