* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

.loader {
  position: relative;
  display: block;
  width: 50px;
  height: 50px;
  vertical-align:  bottom;
}

.box {
  width: 45%;
  height: 45%;
  background: rgba(255, 255, 255, 0.7);
  opacity: 0;
  -webkit-filter: blur(1px);
  animation: load 1s linear infinite;
}
.box:nth-of-type(1) {
  position: absolute;
  top: 2.5%;
  left: 2.5%;
}
.box:nth-of-type(2) {
  position: absolute;
  top: 2.5%;
  right: 2.5%;
  animation-delay: -0.25s;
}
.box:nth-of-type(3) {
  position: absolute;
  bottom: 2.5%;
  right: 2.5%;
  animation-delay: -0.5s;
}
.box:nth-of-type(4) {
  position: absolute;
  bottom: 2.5%;
  left: 2.5%;
  animation-delay: -0.75s;
}

@keyframes load {
  0% {
    opacity: 0;
  }
  30% {
    opacity: 0;
  }
  90% {
    opacity: 1;
  }
  100% {
    opacity: 0;
  }
}