spinner.css

@-webkit-keyframes spinnerframes {
  0%    { height: 25%; }
  50%   { height: 40%; }
  100%  { height: 100%; }
}

@keyframes spinnerframes {
  0%    { height: 25%; }
  50%   { height: 40%; }
  100%  { height: 100%; }
}

.spinner {
  display: block;
  margin: 50px auto;
  position: relative;
  height: 18px;
  width: 18px;
}

.spinner.large {
  height: 32px;
  width: 32px;
}

.spinner .bar {
  border-radius: 2px;
  background: hsl(0, 0%, 83%);
  display: block;
  width: 30%;
  position: absolute;
  height: 0;

  -webkit-animation-name: spinnerframes;
  -webkit-animation-direction: alternate;
  -webkit-animation-duration: 0.35s;
  -webkit-animation-timing-function: linear;
  -webkit-animation-iteration-count: infinite;

  animation-name: spinnerframes;
  animation-direction: alternate;
  animation-duration: 0.35s;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}

.spinner .bar.bar1 {
  top: 0;
  left: 0;
}

.spinner .bar.bar2 {
  top: 0;
  left: 35%;
  -webkit-animation-delay:  0.1s;
  animation-delay:          0.1s;
}

.spinner .bar.bar3 {
  top: 0;
  left: 70%;
  -webkit-animation-delay:  0.2s;
  animation-delay:          0.2s;
}


.bd-example-modal-lg .modal-dialog .modal-content {
    background-color: transparent;
    border: none;
}

.bd-example-modal-lg .modal-dialog{
    display: table;
    position: relative;
    margin: 0 auto;
    top: calc(50% - 24px);
}