title: Letters displayed ridiculously huge (or small) when using 'em' to specify font-size
body: <p>I'm experiencing some pretty bizarre behaviour from my CSS font-size rules. I'm probably doing something silly myself [this must be the case ;-) ], but I hope someone can point it out for me.</p>
  <p>Currently (for testing purposes) I have only one rule for font-size in the stylesheet, that regulates ALL font-sizes, and this is it:</p>
  <pre><code>p, div, a, span {
      font-size:3em;
  }
  </code></pre>
  <p>Now I know 3em is a pretty big font-size (for all I know it should correspond to a width of about 3*16 = 48 pixels on the big screen browsers), but what you see in reality is simply ridiculous. Have a look: <a href="http://www.svvreewijkdevaan.nl/nl/" rel="nofollow noreferrer">http://www.svvreewijkdevaan.nl/nl/</a></p>
  <p>If you think the font size in the menu (which you see on top of the page) is big, scroll down a bit, and you'll find that the letters become so huge that they're not really recognizable as letters anymore.</p>
  <p>And in fact, looking in the Firefox inspection tool, I find that '3em' letters are computed to have a font-size of (get this) 34992px, i.e. almost 35 thousand. What does that even mean?</p>
  <p>In fact, the real (displayed) font-size (i.e. the width) seems to grow - at the very least - <em>exponentially</em> with the specified em number, rather than proportionally. So for example, if I replace 3em by 3.5em, the displayed font-size becomes at least two times as wide (actually more). Conversely, if I reduce the specified font-size to 1em I get the - normal and expected - size of about 16px. But if I make it 0.7em, the width reduces to maybe 2px (absolutely unreadably small).</p>
  <p>Why don't the real (displayed) font-sizes grow proportionally with font-size (in terms of 'em') specified in my stylesheet?</p>