.header {
position: absolute;
top:50%;
left:50%;
margin-top: -100px;
margin-left: -90px;
color : #000000;
}
.lds-grid {
  display: inline-block;
    position: absolute;
    top: 50%;
    left: 50%;
    margin-top: -50px;
    margin-left: -50px;
    width: 100px;
    height: 100px;
}
.lds-grid div {
  position: absolute;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #000000;
  animation: lds-grid 1.2s linear infinite;
}
.lds-grid div:nth-child(1) {
  top: 8px;
  left: 8px;
  animation-delay: 0s;
}
.lds-grid div:nth-child(2) {
  top: 8px;
  left: 32px;
  animation-delay: -0.4s;
}
.lds-grid div:nth-child(3) {
  top: 8px;
  left: 56px;
  animation-delay: -0.8s;
}
.lds-grid div:nth-child(4) {
  top: 32px;
  left: 8px;
  animation-delay: -0.4s;
}
.lds-grid div:nth-child(5) {
  top: 32px;
  left: 32px;
  animation-delay: -0.8s;
}
.lds-grid div:nth-child(6) {
  top: 32px;
  left: 56px;
  animation-delay: -1.2s;
}
.lds-grid div:nth-child(7) {
  top: 56px;
  left: 8px;
  animation-delay: -0.8s;
}
.lds-grid div:nth-child(8) {
  top: 56px;
  left: 32px;
  animation-delay: -1.2s;
}
.lds-grid div:nth-child(9) {
  top: 56px;
  left: 56px;
  animation-delay: -1.6s;
}
@keyframes lds-grid {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.5;
  }
}