HTMLify

@import url("https://fonts.googleapis.com/css2?family=Poppins:wght@300;400;500;600;700;800;900&display=swap");

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Poppins", sans-serif;
}

body {
    display: grid;
    place-items: center;
    background: #ebafcb;
    min-height: 100vh;
}

.btn {
    position: relative;
    padding: 12px 40px;
    font-size: 1.05em;
    border-radius: 40px;
    background: #151515;
    color: #ebafcb;
    letter-spacing: 0.15em;
    text-decoration: none;
    text-transform: uppercase;
    user-select: none;
    transition: 0.5s;
    overflow: hidden;
}

.btn:hover {
    color: #fff;
}

.btn span {
    position: absolute;
    border: 2px solid #fff;
    transform: translate(-50%, -50%);
    pointer-events: none;
    border-radius: 50%;
    animation: animate 2s linear infinite;
}

@keyframes animate {
    0% {
        width: 0;
        height: 0;
    }

    100% {
        width: 350px;
        height: 350px;
    }
}