Resizing a button

I have a "button" that I wish to use all throughout my site, but depending on where in the site the button is, I want it to display at different sizes.

In my HTML I have tried (but its not working):

<div class="button" width="60" height="100">This is a button</div>

And the matching CSS:

.button {
  background-color: #000000;
  color: #FFFFFF;
  float: right;
  padding: 10px;
  border-radius: 10px;
  -moz-border-radius: 10px;
  -webkit-border-radius: 10px;
}

I assumed that if each time I call this class I can just pass in a size and hey-presto!....but not....

By adding the width and height as I call the button class seems to do nothing to the size of it. Does anyone know how I can do this? And if I put the width and height in the CSS then the button will be the same size everywhere.