.custom-parallax::before {
  content: "";
  display: block;
  position: fixed;
  top: 0;
  left: 0;
  z-index: -1;
  width: 100%;
  height: 100vh;
  background-repeat: no-repeat;
  background-position: 50% 100%;
  background-image: url("/assets/img/top.jpg");
  background-size: cover;
  background-blend-mode: multiply;
  background-color: rgba(75, 85, 99, 0.3); /* Tailwindのgray-500に相当 */
}