<div class="button">
    <span>立即下载</span>
</div>

.button {
    width: 200px;
    height: 46px;
    line-height: 46px;
    background: #2e82ff;
    color: #ffffff;
    font-size: 18px;
    border-radius: 27px;
    animation: zoomIn 1.5s infinite;
    text-align: center;
}
@keyframes zoomIn {
    50% {
     transform: scale(1.2);
    }
    100% {
     transform: scale(1);
    }
}