Eric Meyer has felt a lot of pain due to line-height, which means us mere mortals are totally up the creak.

He posted about how line-height is abnormal and goes into detail on his learning curve, and the pain he saw which lead him too:

Why bring all this up? Because I went and poked line-height: normal with a stick, and found it to be both squamous and rugose. As with all driven to such madness, I now seek, grinning wildly, to infect others.

Here’s the punchline: the effects of declaring line-height: normal not only vary from browser to browser, which I had expected—in fact, quantifying those differences was the whole point—but they also vary from one font face to another, and can also varying within a given face.

I did not expect that. At least, not consciously.

He created a tool that visualizes all of this for you, so you can see the magic at work: