I discovered an interesting oddity on the iPhone – when it’s in landscape orientation, it automatically bumps up your font sizes, in an attempt to increase the legibility of non-responsive sites. Of course if you weren’t planning on this, it presents a bit of a problem. At first I thought that I had messed up my viewport settings, which threw me off the trail. The solution turned out to be quite simple:
When it’s set to ‘auto’ (the default value), the iPhone sets the value to somewhere around 135% when it’s in landscape. So head’s up!