what is @ sign as a css selector? : <p>I saw this in a css file:</p>

<pre><code>@-webkit-keyframes loading-spinner-anim {
  0% { opacity: 1}
  100% {opacity: 0}
}
@keyframes loading-spinner-anim {
  0% { opacity: 1}
  100% {opacity: 0}
}
</code></pre>

<p>what do these selectors mean?</p>

<p><code>@keyframes</code> it's not a class or id selector.</p>

<p><code>loading-spinner-anim</code> - the space means it's a child element of the first selector. But it's not a class or id selector.</p>
