style.css

/* * {
    margin-top: 0;
} */

html {
    font-size: 10px;
    background-image: url(alan-walker-concert-logo-bo.jpg) ;
    background-size: cover;  

}    

body,html {
    margin: 0;
    padding: 0;
    font-family: 'Lucida Handwriting';
}

.keys {
    display: flex;
    /* flex-direction: row; */
    flex: 1;
    min-height: 100vh;
    align-items: center;
    justify-content: center;
    

}

.key {
    border: .4rem solid black;
    border-radius: 0.5rem;
    margin: 1rem;
    font-size: 1.5rem;
    padding: 1rem .5rem;
    transition: all 0.07s;
    width: 10rem;
    text-align: center;
    color: white;
    background: rgba(0,0,0,0.4);
    text-shadow: 0 0 .5rem black;
}

kbd {
    display: block;
    font-size: 4rem;
}

.sound {
    font-size: 1.2rem;
    text-transform: uppercase;
    letter-spacing: .1rem;
    color: yellow;
}

.playing {
    transform: scale(1.1);
    border-color: yellow;
    box-shadow: 0 0 1rem yellow;
}