JSFiddle - React, Tailwind, and code Playground

HTML

<h1>
       This is a title
</h1>

CSS

//@-webkit-keyframes titleAnimation { from { font-size:10px; } to { font-size:30px; } }
//@-moz-keyframes titleAnimation { from { font-size:10px; } to { font-size:30px; } }
@keyframes titleAnimation { from { font-size:10px; } to { font-size:30px; } }

h1 {
    -webkit-animation:titleAnimation ease-in 1;
    -moz-animation:titleAnimation ease-in 1;
    animation:titleAnimation ease-in 1;

    -webkit-animation-fill-mode:forwards;
    -moz-animation-fill-mode:forwards;
    animation-fill-mode:forwards;

    -webkit-animation-duration:1s;
    -moz-animation-duration:1s;
    animation-duration:1s;
}