css实现循环扩散光圈的效果

效果：

@keyframes warn {
    0% {
        transform: scale(0);
        opacity: 0.0;
    }
    25% {
        transform: scale(0);
        opacity: 0.1;
    }
    50% {
        transform: scale(0.1);
        opacity: 0.3;
    }
    75% {
        transform: scale(0.5);
        opacity: 0.5;
    }
    100% {
        transform: scale(1);
        opacity: 0.0;
    }
}
@-webkit-keyframes "warn" {
    0% {
        -webkit-transform: scale(0);
        opacity: 0.0;
    }
    25% {
        -webkit-transform: scale(0);
        opacity: 0.1;
    }
    50% {
        -webkit-transform: scale(0.1);
        opacity: 0.3;
    }
    75% {
        -webkit-transform: scale(0.5);
        opacity: 0.5;
    }
    100% {
        -webkit-transform: scale(1);
        opacity: 0.0;
    }
}

/* 保持大小不变的小圆圈  */
.dot {
    position: absolute;
    width: 50px;
    height: 50px;
    left: -15px;
    top: -15px;
    -webkit-border-radius: 100;
    -moz-border-radius: 100;
    border: 20px solid #f6c100;
    border-radius: 100%;
    z-index: 2;
    opacity: 0;
    -webkit-animation: warn 3s ease-out;
    -moz-animation: warn 3s ease-out;
    animation: warn 3s ease-out;
    -webkit-animation-iteration-count: infinite;
    -moz-animation-iteration-count: infinite;
    animation-iteration-count: infinite;
}
/* 产生动画（向外扩散变大）的圆圈  */
.pulse {
    position: absolute;
    width: 50px; 
    height: 50px;
    left: -15px;
    top: -15px;
    border: 20px solid #f6c100;
    -webkit-border-radius: 100%;
    -moz-border-radius: 100%;
    border-radius: 100%;
    z-index: 1;
    opacity: 1;
    -webkit-animation: warn 2s ease-out;
    -moz-animation: warn 2s ease-out;
    animation: warn 2s ease-out;
    -webkit-animation-iteration-count: infinite;
    -moz-animation-iteration-count: infinite;
    animation-iteration-count: infinite;
}

.icon-warnCom{ position: absolute; width: 12px; height: 12px; background-color: #ffd803; border-radius: 100%; top: 100px; left: 100px;}
.icon-warns{ position: relative; width: 100%; height: 100%; display: block;}
.icon-warnCom .dot,.icon-warnCom .pulse{ left: -24px; top: -24px; width: 60px; height: 60px}