I'm making a back-end website that is Angular + Bootstrap. So this should work on practically all browsers.
On my develop machine, the site works perfect, responsiveness is good, when I resize the browser, the site reacts. But on my iPhone the site always opened zoomed out. So too small to read. I was expecting it to react responsize.
This problem was solved by adding this meta tag:
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
Make sure also to clear the browsing history.