html
<img src="images/t1wsqsfgnaxxxmjxp6-470-50.png" class="fly updown" alt="">
css
.fly {
position: absolute;
right: 20%;
top: 10%
}
js
.updown {/* 类似于 js 调用函数 */
animation: fly 3s linear infinite; /* linear 匀速 infinite无限循环*/
}
@keyframes fly { /* 类似于js 的声明函数 function */
0% {
top: 10%;
}
50% {
top: 20%;
}
100% {
top: 10%;
}
}