Dynamically change color to lighter or darker by percentage CSS (Javascript)

Question

We have a big application on the site and we have a few links which are, let\'s say blue color like the blue links on this site. Now I want to make some other links, but wit

Answer 1

One outdated simple answer (in 2013) was to use a 50% transparent white PNG over the color:

div {
    background-color:red;
}

div:hover {
    background-image:url('lighten.png');
}

Where lighten.png is a PNG of a white fill with 50% transparency.

There's much better ways to do this today. I hope people stop commenting now.