"Mouse movement button with border-radius"
Bootstrap 4.1.1 Snippet by koshikojha

<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css"> <script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script> <script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script> <!------ Include the above in your HEAD tag ----------> <button class="button"> <span>Hover me I'm awesome</span> </button>
body { display: flex; justify-content: center; align-items: center; min-height: 100vh; background: white; } .button { position: relative; appearance: none; background: #f72359; padding: 1em 2em; border: none; color: white; font-size: 1.2em; cursor: pointer; outline: none; overflow: hidden; border-radius: 100px; } span { position: relative; pointer-events: none; } button::before { --size: 0; content: ''; position: absolute; left: var(--x); top: var(--y); width: var(--size); height: var(--size); background: radial-gradient(circle closest-side, #4405f7, transparent); transform: translate(-50%, -50%); transition: width .2s ease, height .2s ease; } button:hover::before { --size: 400px; }
document.querySelector('.button').onmousemove = (e) => { const x = e.pageX - e.target.offsetLeft const y = e.pageY - e.target.offsetTop e.target.style.setProperty('--x', `${ x }px`) e.target.style.setProperty('--y', `${ y }px`) }

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