body {
  height: 100vh;
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: #0a3d62;
}

.loader {
  position: relative;
  width: 90px;
  height: 90px;
  display: flex;
  flex-direction: column;
  flex-wrap: wrap;
}

span {
  width: 30px;
  height: 30px;
  position: relative;
}

span:before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: white;
  animation: loading 1s linear infinite;
}

@keyframes loading {
  0% { width: 100%;
  height: 100%; }
  100% { width: 0;
  height: 0; }
}

.s4:before,
.s5:before,
.s6:before {
  animation-delay: 0.1s;
}

.s7:before,
.s8:before,
.s9:before {
  animation-delay: 0.2s;
}