#loader-screen
{
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,.3);
    display: none;
}

.loader {
    position: absolute;
    border: 16px solid #f3f3f3; /* Light grey */
    border-top: 16px solid #3498db; /* Blue */
    border-radius: 50%;
    width: 120px;
    height: 120px;
    animation: spin 2s linear infinite;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
  }
  
  @keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
  }