JSFiddle - React, Tailwind, and code Playground

HTML

<div class="hs_submit">
    <div class="actions">
    <button type="submit" value="DOWNLOAD NOW!" class="button__item"> dfgdf d df </button>
      
      
    </div>
  </div>

CSS

.button__item {
    font-family: "Raleway", sans-serif;
    font-weight: 500;
    text-transform: uppercase;
    font-size: 1.313rem;
    line-height: 1em;
    color: #333333;
    letter-spacing: 0;
    background: #fff336;
    padding: 32.5px 65px;
    display: inline-block;
    position: relative;
    cursor: pointer;
    -webkit-transition: 0.3s;
    transition: 0.3s;
        transition-timing-function: ease;
    -webkit-transition-timing-function: ease-out;
    transition-timing-function: ease-out;
}


.button__item::after {
    content: "";
    background: #fff;
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 0;
    z-index: -1;
    -webkit-transition: 0.3s;
    transition: 0.3s;
}

.button__item:hover {
    transform: translateY(0px);
}

.button__item:hover::after {
    height: 100%;
}