html, body {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  background-color: #252a34;
}

div {
  font-family: roboto, helvetica;
  letter-spacing: 1px;
  padding: 1rem 5rem;
  border-radius: 9px;
  font-size: 1.5rem;
  color: #ff2e63;
  font-weight: bold;
  border: 2px solid #ff2e63;
  box-shadow: 0 3px 12px 0 rgba(0, 0, 0, 0.5);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  --a: initial;
}
div:after {
  content: "";
  position: absolute;
  top: var(--top);
  left: var(--left);
  width: var(--diameter);
  height: var(--diameter);
  transform: scale(0);
  background-color: rgba(255, 255, 255, 0.4);
  border-radius: 50%;
  pointer-events: none;
  animation: var(--a);
}

@keyframes ripple-effect {
  100% {
    transform: scale(1);
    opacity: 0;
  }
}
#tube {
  position: absolute;
  bottom: 1vw;
  right: 1vw;
  opacity: 0.4;
}
#tube > img {
  height: 3rem;
}
#tube:hover {
  opacity: 1;
}