html {
    font-size: 10px;
    background: url('./img/guitar.jpg') bottom center;
    height: 100vh;
    background-size: cover;
}

body,
html {
    margin: 0;
    padding: 0;
    font-family: sans-serif;
}

.keys {
    display: flex;
    flex: 1;
    min-height: 50vh;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
}

.key {
    border: .4rem solid black;
    border-radius: .5rem;
    margin: 1rem;
    font-size: 1.5rem;
    padding: 1rem .5rem;
    transition: all .07s ease;
    width: 10rem;
    text-align: center;
    color: white;
    background: rgba(0, 0, 0, 0.5);
    text-shadow: 0 0 .5rem black;
}

.playing {
    transform: scale(1.1);
    border-color: #ffc600;
    box-shadow: 0 0 1rem #ffc600;
}

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

.sound {
    font-size: 1.2rem;
    text-transform: uppercase;
    letter-spacing: .1rem;
    color: #ffc600;
}

h1 {
    text-align: center;
    color: white;
    background: rgba(0, 0, 0, 0.5);
    text-shadow: 0 0 .5rem black;
    padding-top: 1rem;
    padding-bottom: 1rem;
}

#backNav {
    background-color: #455A64ad;
    width: 150px;
    height: 50px;
    position: fixed;
    left: 0;
    bottom: 0;
    text-align: center;
    z-index: 100;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

#backNav a {
    color: white;
    font-size: 1.5rem;
}