* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  position: relative;
  z-index: 1;
}

html {
  width: 100%;
  height: auto;
  font-size: 18px;
  /* overflow: hidden; */
}

body {
  width: 100%;
  min-height: 100%;
  display: flex;
  background: #e5e5e5;
  /* overflow: hidden; */
}

.drop-container {
  position: fixed;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
  z-index: 0;
}

/* .drop {
  position: relative;
  position: absolute;
  z-index: 0;
  transform-origin: 50% 50%;
  transform: translate(-50%, -50%);
  width: 50vmin;
  height: 50vmin;
  border-radius: 50%;
  filter: blur(1vmin);
  box-shadow:
    -5vmin -5vmin 5vmin #eeeeee,
    5vmin 5vmin 5vmin #bfbfbf,
    inset -5vmin -5vmin 5vmin #eeeeee,
    inset 5vmin 5vmin 5vmin #bfbfbf;
  border: 0 solid #e5e5e5;
  animation: expand 4s cubic-bezier(0.165, 0.84, 0.44, 1) 2;
} */

.drop {
  position: absolute;
  z-index: 0;
  transform-origin: 50% 50%;
  transform: translate(-50%, -50%) translateZ(0);
  will-change: transform, opacity;
  width: 50vmin;
  height: 50vmin;
  border-radius: 50%;
  filter: blur(0.5vmin); /* 軽量化 */
  box-shadow: 
    -5vmin -5vmin 5vmin #eeeeee,
    5vmin 5vmin 5vmin #bfbfbf,
    inset -5vmin -5vmin 5vmin #eeeeee,
    inset 5vmin 5vmin 5vmin #bfbfbf;
  border: 0 solid #e5e5e5;
  animation: expand 4s cubic-bezier(0.165, 0.84, 0.44, 1) 2;
}


@keyframes expand {
  0% {
    width: 0;
    height: 0;
    box-shadow:
      -5vmin -5vmin 5vmin #eeeeee,
      5vmin 5vmin 5vmin #bfbfbf,
      inset -5vmin -5vmin 5vmin #eeeeee,
      inset 5vmin 5vmin 5vmin #bfbfbf;
    border: 0 solid rgba(229, 229, 229, 0.5);
  }
  5% {
    box-shadow:
      -5vmin -5vmin 5vmin #eeeeee,
      5vmin 5vmin 5vmin #bfbfbf,
      inset -5vmin -5vmin 5vmin #eeeeee,
      inset 5vmin 5vmin 5vmin #bfbfbf;
    border: 2vmin solid rgba(229, 229, 229, 0.5);
  }
  90% {
    box-shadow: none;
    border: 2vmin solid rgba(229, 229, 229, 0.5);
  }
  100% {
    width: 100vmin;
    height: 100vmin;
    box-shadow: none;
    border: 0 solid rgba(229, 229, 229, 0.5);
  }
}

.drop:before {
  content: '';
  position: absolute;
  margin: auto;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  width: 0%;
  height: 0%;
  border-radius: 50%;
  animation: expand1 4s cubic-bezier(0.165, 0.84, 0.44, 1) 2;
  box-shadow:
    -5vmin -5vmin 5vmin #eeeeee,
    5vmin 5vmin 5vmin #bfbfbf,
    inset -5vmin -5vmin 5vmin #eeeeee,
    inset 5vmin 5vmin 5vmin #bfbfbf;
}

@keyframes expand1 {
  0% {
    width: 0%;
    height: 0%;
    box-shadow:
      -5vmin -5vmin 5vmin #eeeeee,
      5vmin 5vmin 5vmin #bfbfbf,
      inset -5vmin -5vmin 5vmin #eeeeee,
      inset 5vmin 5vmin 5vmin #bfbfbf;
    border: 0 solid #e5e5e5;
  }
  20% {
    box-shadow:
      -5vmin -5vmin 5vmin #eeeeee,
      5vmin 5vmin 5vmin #bfbfbf,
      inset -5vmin -5vmin 5vmin #eeeeee,
      inset 5vmin 5vmin 5vmin #bfbfbf;
  }
  100% {
    width: 60%;
    height: 60%;
    box-shadow: none;
    border: 1vmin solid #e5e5e5;
  }
}