.bg-bubbles li {
    position: absolute;
    list-style: none;
    display: block;
    width: 40px;
    height: 40px;
    background-color: rgba(0, 0, 0, 0.4);
    bottom: -160px;
    -webkit-animation: square 20s infinite;
    animation: square 20s infinite;
    -webkit-transition-timing-function: linear;
    transition-timing-function: linear;
  }
  .bg-bubbles li:nth-child(1) {
    left: 10%;
  }
  .bg-bubbles li:nth-child(2) {
    left: 20%;
    width: 80px;
    height: 80px;
    -webkit-animation-delay: 1s;
            animation-delay: 1s;
    -webkit-animation-duration: 17s;
            animation-duration: 17s;
  }
  .bg-bubbles li:nth-child(3) {
    left: 25%;
    -webkit-animation-delay: 2s;
            animation-delay: 2s;
  }
  .bg-bubbles li:nth-child(4) {
    left: 40%;
    width: 60px;
    height: 60px;
    -webkit-animation-duration: 22s;
    animation-duration: 22s;
    background-color: rgba(255, 255, 255, 0.25);
  }
  .bg-bubbles li:nth-child(5) {
    left: 70%;
  }
  .bg-bubbles li:nth-child(6) {
    left: 80%;
    width: 120px;
    height: 120px;
    -webkit-animation-delay: 1.5s;
    animation-delay: 1.5s;
    background-color: rgba(255, 255, 255, 0.2);
  }
  .bg-bubbles li:nth-child(7) {
    left: 32%;
    width: 160px;
    height: 160px;
    -webkit-animation-delay: 4s;
    animation-delay: 4s;
  }
  .bg-bubbles li:nth-child(8) {
    left: 55%;
    width: 20px;
    height: 20px;
    -webkit-animation-delay: 5s;
            animation-delay: 5s;
    -webkit-animation-duration: 40s;
            animation-duration: 40s;
  }
  .bg-bubbles li:nth-child(9) {
    left: 25%;
    width: 10px;
    height: 10px;
    -webkit-animation-delay: 1s;
            animation-delay: 1s;
    -webkit-animation-duration: 30s;
            animation-duration: 30s;
    background-color: rgba(255, 255, 255, 0.3);
  }
  .bg-bubbles li:nth-child(10) {
    left: 90%;
    width: 160px;
    height: 160px;
    -webkit-animation-delay: 4s;
            animation-delay: 4s;
  }
  @-webkit-keyframes square {
    0% {
      -webkit-transform: translateY(0);
              transform: translateY(0);
    }
    100% {
      -webkit-transform: translateY(-700px) rotate(600deg);
              transform: translateY(-700px) rotate(600deg);
    }
  }
  @keyframes square {
    0% {
      -webkit-transform: translateY(0);
              transform: translateY(0);
    }
    100% {
      -webkit-transform: translateY(-700px) rotate(600deg);
              transform: translateY(-700px) rotate(600deg);
    }
  }