#background {
  position: absolute;
  top: 0;
  left: 0;

  width: 100%;
  height: 100%;

  /* hide it on mobile */
  display: none;
}

@media not all and (hover: none) {
  #background {
    display: block;
  }
}

#blob {
  position: absolute;
  top: 50%;
  left: 50%;

  translate: -50% -50%;

  width: 25vmax;
  height: 25vmax;

  z-index: -2;

  border-radius: 50%;
  overflow: hidden;
  display: flex;

  animation: rotate 15s infinite;

  background: linear-gradient(to right, #03a9f4, #42a5f5);

  /* hide it on mobile */
  opacity: 0;
}

@keyframes rotate {
  from {
    rotate: 0deg;
  }

  50% {
    scale: 1.3 1;
  }

  to {
    rotate: 360deg;
  }
}

#blur {
  position: absolute;
  height: 100%;
  width: 100%;

  z-index: -1;

  backdrop-filter: blur(15vmax);
}