.radio-img-group input {
  margin: 0;
  padding: 0;
  appearance: none;
}

.radio-img {
  cursor: pointer;
  background-size: contain;
  background-repeat: no-repeat;
  display: inline-block;
  margin: 0 10px;
  transition: all 100ms ease-in;
  filter: brightness(1.0) grayscale(1) opacity(1);
}

.radio-img:hover {
  filter: brightness(1.2) grayscale(.5) opacity(1);
}

.radio-img-group input:active + .radio-img {
  opacity: 1;
}

.radio-img-group input:checked + .radio-img {
  filter: none;
}