swiper/modules/lazy/lazy.scss

/* Preloader */
@at-root {
  :root {
    /*
  --swiper-preloader-color: var(--swiper-theme-color);
  */
  }
}
.swiper-lazy-preloader {
  width: 42px;
  height: 42px;
  position: absolute;
  left: 50%;
  top: 50%;
  margin-left: -21px;
  margin-top: -21px;
  z-index: 10;
  transform-origin: 50%;
  box-sizing: border-box;
  border: 4px solid var(--swiper-preloader-color, var(--swiper-theme-color));
  border-radius: 50%;
  border-top-color: transparent;
}
.swiper:not(.swiper-watch-progress),
.swiper-watch-progress .swiper-slide-visible {
  .swiper-lazy-preloader {
    animation: swiper-preloader-spin 1s infinite linear;
  }
}

.swiper-lazy-preloader-white {
  --swiper-preloader-color: #fff;
}
.swiper-lazy-preloader-black {
  --swiper-preloader-color: #000;
}
@keyframes swiper-preloader-spin {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}