title: What does half a pixel mean in the font-size CSS property?
body: <p>I'm currently working on a website redesign and I'm receiving a list with the required changes from an agency.</p>
  
  <p>The header menu of the site currently has the following styles:</p>
  
  <pre><code>line-height: 1em;
  font-size: 11px;
  </code></pre>
  
  <p>In one of the documents I have received there's a change request that requires me to change those styles to:</p>
  
  <pre><code>line-height: 1.2em;
  font-size: 11.5px;
  </code></pre>
  
  <p>I know that the EMs are OK with the decimal values but what does half a pixel mean in the font size? I have tried to change the font size using the inspector from <em>12</em> to <em>11.5</em> and to <em>11</em> and the change from <em>11</em> to <em>11.5</em> is visible but the one from <em>11.5</em> to <em>12</em> it moves just a little (I thins only the spacing changes a little, but it is set to <em>1em</em> on all 3 examples). You can check the screen-shots below:
  <img src="https://i.stack.imgur.com/oXq0l.png" alt="enter image description here"></p>
  
  <p>So what does that half a pixel mean in the context of a web-page? Is this cross-browser and what does that <em>.5</em> pixel do to the font-size?</p>