body {
  height: 100vh;
  width: 100vw;
  margin: 0;
  background: url(https://source.unsplash.com/N3o-leQyFsI/1080x720) no-repeat 50% 50%;
  background-size: cover;
}
svg {
  max-width: 50vw;
  max-height: 65vh;
  display: block;
  position: absolute;
  left: 53%;
  top: 42%;
  transform: translate(-50%, -50%);
}
#Signature path {
  fill: black;
}
mask path {
  fill: none;
  stroke: white;
}
#Mouse path,
mask path {
  animation-duration: var(--duration);
  animation-timing-function: ease-in;
  animation-iteration-count: 1;
  animation-fill-mode: forwards;
  stroke-dasharray: var(--length) var(--length);
  stroke-dashoffset: var(--length);
  animation-name: brush;
  animation-delay: var(--delay);
}
@keyframes brush {
  0% {
    stroke-dashoffset: var(--length);
  }
  100% {
    stroke-dashoffset: 0;
  }
}