title: Attribute changeable by animation and accesible by [attribute=value]
body: <p>I am currently trying to make an animation that changes an attribute which can be accessed by [attribute=value] like so:</p>
  
  <pre><code>.test {
  Animation: someAnimation 5s infinite;
  }
  @keyframes someAnimation{
      20% {someAttribute: someValue;}
      40% {someAttribute: someValue;}
  }
  .test[someAttribute=someValue]{
  background-color: red;
  }
  </code></pre>
  
  <p>What would SomeAttribute be if anything?</p>
  
  <p>Note: I am explicitly looking for the background-color to be changed by accessing <code>SomeAttribute</code></p>