vant/packages/vant-css/src/loading.css

@import './common/var.css';

.van-loading {
  width: 30px;
  height: 30px;
  z-index: 0;
  font-size: 0;
  line-height: 0;
  position: relative;
  vertical-align: middle;

  &--circle {
    width: 16px;
    height: 16px;
  }

  &__spinner {
    z-index: -1;
    width: 100%;
    height: 100%;
    position: relative;
    display: inline-block;
    box-sizing: border-box;
    animation: van-rotate 0.8s linear infinite;

    &--circle {
      border-radius: 100%;
      border: 3px solid transparent;
    }

    &--gradient-circle {
      background-size: contain;
    }

    &--spinner {
      animation-timing-function: steps(12);

      i {
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        position: absolute;

        &::before {
          width: 2px;
          height: 25%;
          content: ' ';
          display: block;
          margin: 0 auto;
          border-radius: 40%;
          background-color: currentColor;
        }
      }
    }

    &--circular {
      animation-duration: 2s;
    }
  }

  &__circular {
    width: 100%;
    height: 100%;

    circle {
      stroke-width: 3;
      stroke-linecap: round;
      animation: van-circular 1.5s ease-in-out infinite;
    }
  }

  &--black {
    .van-loading__spinner--circle {
      border-color: $gray;
      border-top-color: $gray-darker;
    }

    .van-loading__spinner--gradient-circle {
      background-image: url('https://img.yzcdn.cn/vant/gradient-circle-black.png');
    }

    .van-loading__spinner--spinner {
      color: $gray;
    }

    circle {
      stroke: $gray;
    }
  }

  &--white {
    .van-loading__spinner--circle {
      border-color: rgba(0, 0, 0, .1);
      border-top-color: rgba(255, 255, 255, .7);
    }

    .van-loading__spinner--gradient-circle {
      background-image: url('https://img.yzcdn.cn/vant/gradient-circle-white.png');
    }

    .van-loading__spinner--spinner {
      color: #fff;
    }

    circle {
      stroke: $white;
    }
  }
}

@keyframes van-circular {
  0% {
    stroke-dasharray: 1, 200;
    stroke-dashoffset: 0;
  }
  50% {
    stroke-dasharray: 90, 150;
    stroke-dashoffset: -40;
  }
  100% {
    stroke-dasharray: 90, 150;
    stroke-dashoffset: -120;
  }
}

@for $i from 1 to 12 {
  .van-loading__spinner--spinner i:nth-of-type($i) {
    opacity: calc(1 - (0.75 / 12) * ($i - 1));
    transform: rotate(calc($i * 30deg));
  }
}