body {
    /*background-image: url("https://picsum.photos/1920/1080");*/
    text-align: center;
    width: 100vw;
    height: 100vh;
    margin: 0;
    overflow: hidden;
}

#background {
    position: absolute;
    left: 0;
    top: 0;
    min-width: 100vw;
    min-height: 100vh;
}

#content {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn {
    font-display: block;
    padding: 1em 2em;
    margin: 0.5em;
    font-size: x-large;
    border-radius: 5%;
    border-color: whitesmoke;
    border-style:groove;
    opacity: 60%;
    cursor: pointer;
}