.loader {
    width: 40px;
    height: 40px;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
    --c:no-repeat linear-gradient(#18d26e 0 0);
    background:
      var(--c) center/100% 10px,
      var(--c) center/10px 100%;
      z-index: 999999;
  }
  
  .loader:before {
    content:'';
    position: absolute;
    inset: 0;
    top: calc(50% - 30px);
    left: calc(50% - 30px);
    background:
      var(--c) 0    0,
      var(--c) 100% 0,
      var(--c) 0    100%,
      var(--c) 100% 100%;
    background-size: 15.5px 15.5px;
    animation: l16 1.5s infinite cubic-bezier(0.3,1,0,1);
  }
  @keyframes l16 {
     33%  {inset:-10px;transform: rotate(0deg)}
     66%  {inset:-10px;transform: rotate(90deg)}
     100% {inset:0    ;transform: rotate(90deg)}
  }