How to assign Advanced Stylesheet to button

Hi, I am learning about CSS and trying to implement in Ignition.

.psc-button_test {
  display: inline-block;
  padding: 15px 25px;
  font-size: 24px;
  cursor: pointer;
  text-align: center;
  text-decoration: none;
  outline: none;
  color: #fff;
  background-color: #4CAF50;
  border: none;
  border-radius: 15px;
  box-shadow: 0 9px #999;
}

.psc-button_test:hover {
  background-color: #3e8e41;
}

.psc-button_test:active {
  background-color: #3e8e41;
  box-shadow: 0 5px #666;
  transform: translateY(4px);
}

Above code I had written in Advanced Stylesheet and I am not able to find this Stylesheet in Style --> Classes.

How I can implement this ?

I answered a similar question on this forum post, but you can type the name of your class directly into the component's style classes.

Thanks alot

The best way however, would be to create a stub class in the Perspective Styles section, without any config if you wish. Then you'll see it in the dropdown