HTMLify

*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    min-height: 100vh;
    display: grid;
    place-items: center;
    background: #121314;
    font-family: serif;
}

.btn {
    font-size: 1.5rem;
    padding: 1rem 3rem;
    color: #f4f4f4;
    text-transform: uppercase;
    text-decoration: none;
    border: 1px solid rgb(146, 148, 248);
    position: relative;
    overflow: hidden;
}

.btn:hover {
    box-shadow: 1px 1px 25px 10px rgba(146, 148, 248, 0.4);
}

.btn::before {
    content: "";
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(120deg,
            transparent,
            rgba(146, 148, 248, 0.4),
            transparent);
    transition: all 650ms;
}

.btn:hover::before {
    left: 100%;
}