css动画，展开折叠图标

@keyframes packupArrowFlow {
    0% {
        bottom:;
    }
    70% {
        bottom: 10px;
    }
}
@-webkit-keyframes packupArrowFlow {
    0% {
        bottom:;
    }
    70% {
        bottom: 10px;
    }
}

.gradient .packupArrow {
    -webkit-animation: packupArrowFlow 1s ease infinite;
    animation: packupArrowFlow 1s ease infinite;
}

使用关键帧动画