.btn {
  border-radius: 3px;
  text-decoration: none;
  user-select: none;
  position: relative;
  overflow: hidden;
  -webkit-user-drag: none;
}

.btn:after {
  content: "";
  position: absolute;
  width: 0;
  height: 0;
  padding: 0;
  top: var(--mouse-y) !important;
  left: var(--mouse-x) !important;
  transform: translate(-50%, -50%);
  background: rgba(255, 255, 255, 0.5);
  border-radius: 50%;
  pointer-events: none;
  transition: width 1s ease, height 1s ease, opacity 0.5s ease;
  opacity: 0;
}

.btn:active:after {
  width: 300px;
  height: 300px;
  opacity: 1;
}