body {
  display: grid;
  height: 100vh;
  place-items: center;
}

input::file-selector-button {
  background-image: linear-gradient(
    to right,
    #ff7a18,
    #af002d,
    #319197 100%,
    #319197 200%
  );
  background-position-x: 0%;
  background-size: 200%;
  border: 0;
  border-radius: 8px;
  color: #fff;
  padding: 1rem 1.25rem;
  text-shadow: 0 1px 1px #333;
  transition: all 0.25s;
}
input::file-selector-button:hover {
  background-position-x: 100%;
  transform: scale(1.1);
}