style.css

html {
    font-size: 10px;
    background: url("img/beyBWsmall.jpg") bottom center;
    background-size: cover;
}

body {
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.title {
    letter-spacing: 0.1rem;
    margin-top: 20px;
    padding: 0 5px 0 30px;
    background-color: black;
    font-family: "Roboto", sans-serif;
    align-self: flex-start;
}

h1 {
    font-size: 40px;
    margin: 0;
    font-family: "Roboto", sans-serif;
    text-transform: uppercase;
    color: #ffc600;
}

h2 {
    font-size: 15px;
    margin-top: -10px;
    color: white;
    font-family: "Open Sans", sans-serif;
}

#container {
    margin: 0;
    padding: 0;
    font-family: sans-serif;
    display: flex;
}

input[type="range"] {
    -webkit-appearance: none;
}

input {
    width: 5vw;
    height: 2vh;
    cursor: pointer;
    box-shadow: 5% 5% 5% #000000;
    background: none;
    border-radius: 0;
    border: 1px solid #000000;
}

input[type="range"]::-webkit-slider-thumb {
    box-shadow: 1px 1px 5px #000000;
    border: 0px solid #000000;
    height: 8px;
    width: 9px;
    border-radius: 4px;
    background: #ffc600;
    cursor: pointer;
    -webkit-appearance: none;
    margin-top: -3px;
}

.keys {
    display: flex;
    flex: 1;
    flex-wrap: wrap;
    min-height: 100vh;
    max-width: 50%;
    align-content: center;
    justify-content: center;
}

.key {
    border: 0.4rem solid black;
    border-radius: 0.5rem;
    margin: 1rem;
    font-size: 1.5rem;
    padding: 1rem 0.5rem;
    transition: all 0.09s ease;
    width: 10rem;
    height: 90px;
    text-align: center;
    color: white;
    background: rgba(0, 0, 0, 0.4);
    text-shadow: 0 0 0.5rem black;
}

.rythmBox {
    display: flex;
    flex-direction: column;
    align-items: center;
}

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

.halo {
    border: 0.4rem solid black;
    border-radius: 0.5rem;
    font-size: 12pt;
    padding: 1rem 0.5rem;
    transition: all 0.07s ease;
    width: 20%;
    margin: auto;
    text-align: center;
    color: #ffc600;
    background: rgba(0, 0, 0, 0.4);
    text-shadow: 0 0 0.5rem black;
    display: block;
    text-transform: uppercase;
    align-self: center;
}

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

.sound {
    font-size: 1.2rem;
    text-transform: uppercase;
    letter-spacing: 0.1rem;
    color: #ffc600;
}