How to make a Xul button bigger using css as it get focus?

Question

I saw at this page that I can use CSS to change my button as it get focused. But trying with the following code in the CSS didn't work:

button:focus {
    style.width='200px';
}

Any idea why it isn't working?

Answer 1

try this:

button:hover { 
  width: 200px;
}