Update index.html (mdn#2576)

realise -> realize

files/en-us/learn/css/first_steps/getting_started/index.html

@@ -206,7 +206,7 @@ <h2 id="Styling_things_based_on_state">Styling things based on state</h2>
   text-decoration: none;
 }</pre>
 
-<p>In the live example below, you can play with different values for the various states of a link. I have added the rules above to it, and now realise that the pink color is quite light and hard to read — why not change that to a better color? Can you make the links bold?</p>
+<p>In the live example below, you can play with different values for the various states of a link. I have added the rules above to it, and now realize that the pink color is quite light and hard to read — why not change that to a better color? Can you make the links bold?</p>
 
 <p>{{EmbedGHLiveSample("css-examples/learn/getting-started/started3.html", '100%', 900)}} </p>