JSFiddle - React, Tailwind, and code Playground

HTML

<banner>i am the banner.
</banner>
<item>item</item>
<item>item</item>
<item>item</item>
<item>item</item>

CSS

banner, item {
    display: block;
    border: 1px solid black;
}
banner {
    background-color: lightgreen;
    height: 40px;
    -webkit-animation: banner-animation 2s linear 0s infinite alternate;
    animation: banner-animation 2s linear 0s infinite alternate;
}
item {
    background-color: lightblue;
    height: 50px;
}

@-webkit-keyframes banner-animation {
    from { height: 340px; }
    to { height: 50px; }
}

@keyframes banner-animation {
    from { height: 340px; }
    to { height:50px; }
}