CSS pseudo classes not working?

Question

css

css just doesn't recognize any pseudo-classes. I'm just learning and maybe this is a common problem, maybe I need to install some plugin?

.button {
  padding: 10px 20px;
  border-radius: 8px;
  font-size: 1.2rem;
  background-color: @btn-color;
  color: @light;
  text-transform: uppercase;
  border: none;
  transition: all 0.2s;
   &:hover {
    cursor: pointer;
    background-color: darken(@btn-color, 5%);
  }
}

Answer 1

Hey!
Your preprocessor code (LESS) must be compiled into CSS using a plugin (collector / npm script), since browsers cannot read a "non-native" language.
Googling a little about preprocessors and everything will work out! :)

Answer 2