一个css3的loading、闪烁效果。

html代码：

 <div class="step-act-icon">
    <div class="ripple ripple1">
     </div>
    <div class="ripple ripple2">
     </div>
    <div class="ripple ripple3">
      </div>
    <div class="ripple ripple4">
    </div>
</div>    

css代码：

.step-act-icon {
        position: absolute;
        left: 0;
        top: 50%;
        margin-top: -11px;
        width: 22px;
        height: 22px;
        border-radius: 50%;
        .ripple {
          position: absolute;
          left: 0;
          top: 50%;
          margin-top: -11px;
          width: 100%;
          height: 100%;
          border-radius: 50%;
          animation: ripple 1s ease-in-out alternate-reverse infinite;
          transform: scale(0);
          opacity: 0.6;
        }
      }
      .step-act-icon .ripple1 {
        background: #92EF69;
      }

      .step-act-icon .ripple2 {
        animation-delay: -250ms;
        background: #71DE41;
      }

      .step-act-icon .ripple3 {
        animation-delay: -500ms;
        background: #64C639;
      }
      .step-act-icon .ripple4 {
        animation-delay: -750ms;
        background: #3E9C14;
      }