<div class="wrapper">
    <a class="button" href="#">Hover me!</a>
</div>

<!-- Filter: https://css-tricks.com/gooey-effect/ -->
<svg style="visibility: hidden; position: absolute;" width="0" height="0" xmlns="http://www.w3.org/2000/svg" version="1.1">
    <defs>
        <filter id="goo"><feGaussianBlur in="SourceGraphic" stdDeviation="10" result="blur" />    
            <feColorMatrix in="blur" mode="matrix" values="1 0 0 0 0  0 1 0 0 0  0 0 1 0 0  0 0 0 19 -9" result="goo" />
            <feComposite in="SourceGraphic" in2="goo" operator="atop"/>
        </filter>
    </defs>
</svg>
:root {
    --bg: #1a1e24;
    --color: #eee;
    --font: Montserrat, Roboto, Helvetica, Arial, sans-serif;
}

.wrapper {
    padding: 1.5rem 0;
    filter: url('#goo');
}

.button {
    display: inline-block;
    text-align: center;
    background: var(--color);
    color: var(--bg);
    font-weight: bold;
    padding: 1.18em 1.32em 1.03em;
    line-height: 1;
    border-radius: 1em;
    position: relative;
    min-width: 8.23em;
    text-decoration: none;
    font-family: var(--font);
    font-size: 1.25rem;
}

.button:before,
.button:after {
    width: 4.4em;
    height: 2.95em;
    position: absolute;
    content: "";
    display: inline-block;
    background: var(--color);
    border-radius: 50%;
    transition: transform 1s ease;
    transform: scale(0);
    z-index: -1;
}

.button:before {
    top: -25%;
    left: 20%;
}

.button:after {
    bottom: -25%;
    right: 20%;
}

.button:hover:before,
.button:hover:after {
    transform: none;
}


/* Demo styles */

body {
    width: 100%;
    height: 100%;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: var(--bg)
}

External CSS

  1. https://fonts.googleapis.com/css?family=Montserrat:700

External JavaScript

This Pen doesn't use any external JavaScript resources.