Extending anchor pseudo-class with a custom button class, but need help!

[zoldos]

I have two anchors which I want to change the look of as shown below. But I don’t think my syntax is correct. Any pointers or suggestions would be greatly appreciated!

a:link button--scroll button, a:visited button--scroll button  {
  background-color:black;
  color: blue;
}

a:hover button--scroll button, a:active button--scroll button  {
  background-color: white;
}

The “button–scroll button” is their current class, which I’m attempting to override with the above values.