The CSS value `background-size: cover` will stretch an image but retain its width to height ratio. However, it will only stretch it until the smallest side reaches 100% of the parent node's same side.

```
/* This is an image of 100px Wide x 50px Tall, so it'll 
   stretch to 100% of the window height and then scale the
   width larger to retain its width-to-height ratio.
 */
body
{
    background-image: url( "/images/test.png" );
    background-size: cover;
    background-position: center;
}

```

I want something that will do a cover but to some larger percentage, for example 130%. (I will be using this in a CSS keyframes animation to make the background image grow/shrink)

How would I do this?