<div class="full"></div>

.full {
  position:fixed;
  inset:0;
  z-index:116;
  display: grid;
  background:#fff;
}
.full:before {
  content:"";
  grid-area:1/1;
  --s:67px; /* shape size */
  --m:4px;  /* line thickness */

  --v1: #fff 119.5deg, #0000 120.5deg;
  --v2: #000  119.5deg, #0000 120.5deg;
  background:
    conic-gradient(at var(--m)              calc(var(--s)*0.5777), transparent 270deg, #000 0deg),
    conic-gradient(at calc(100% - var(--m)) calc(var(--s)*0.5777), #000 90deg,  transparent 0deg),
    conic-gradient(from -60deg at 50% calc(var(--s)*0.8662)             , var(--v1)),
    conic-gradient(from -60deg at 50% calc(var(--s)*0.8662 + 2*var(--m)), var(--v2)),
    conic-gradient(from 120deg at 50% calc(var(--s)*1.4435 + 3*var(--m)), var(--v1)),
    conic-gradient(from 120deg at 50% calc(var(--s)*1.4435 +   var(--m)), var(--v2)),
    linear-gradient(90deg, #fff calc(50% - var(--m)),#000 0 calc(50% + var(--m)), #fff 0);
  background-size: calc(var(--s) + 2*var(--m)) calc(var(--s)*1.732 + 3*var(--m)); 
  -webkit-mask:linear-gradient(-60deg,#0000 calc(50% - 4*var(--s)),#000,#0000 calc(50% + 4*var(--s))) right/300% 100% no-repeat;
  animation:f 3s infinite linear;
}
.full:after {
  content:"Loading...";
  grid-area:1/1;
  font-family:monospace;
  font-weight:bold;
  font-size:13vmin;
  margin:auto;
  mix-blend-mode:difference;
  color: #fff;
}

@keyframes f {
  100% {-webkit-mask-position:left}
}