<style>
@keyframe example {
    0%   {font-size-adjust: 0.5;} /* Starting Frame */
    100% {font-size-adjust: 0.7;} /* Ending Frame */
}

i.bars {
    animation-name: example;  /* Defined Animation Name in @keyframe "example" */
    animation-duration: 1s;  /* Duration of the animation, can be .# values to speed up, the higher the value the slower the animation */
    animation-iteration-count: infinite; /* Repeats the animation */
    animation-direction: alternate; /* Starts from 0% then 100% then back to 0%, repeating. */
    animation-timing-function: ease-in-out;  /* Smooths the animation from beginning to end. */
}
</style>