:root {
  --main-bg-color: #0e699b;
}

html {
  background: var(--main-bg-color);
  overflow: hidden;
  height: 100%;
}

#bg {
  position: absolute;
  top: 0;
}

.hidden {
  display: none !important;
}

.arrows {
  width: 60px;
  height: 72px;
  position: absolute;
  left: 50%;
  margin-left: -30px;
  bottom: 20px;
}

.arrows path {
  stroke: #fff;
  fill: transparent;
  stroke-width: 1px;
  animation: arrow 2s infinite;
  -webkit-animation: arrow 2s infinite;
}

@keyframes arrow {
  0% {
    opacity: 0;
  }
  40% {
    opacity: 1;
  }
  80% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}

@-webkit-keyframes arrow /*Safari and Chrome*/ {
  0% {
    opacity: 0;
  }
  40% {
    opacity: 1;
  }
  80% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}

.arrows path.a1 {
  animation-delay: -1s;
  -webkit-animation-delay: -1s; /* Safari 和 Chrome */
}

.arrows path.a2 {
  animation-delay: -0.5s;
  -webkit-animation-delay: -0.5s; /* Safari 和 Chrome */
}

.arrows path.a3 {
  animation-delay: 0s;
  -webkit-animation-delay: 0s; /* Safari 和 Chrome */
}