style.css

@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@100;200;300;400;500;600;700;800;900&display=swap');

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

body{
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background: #e3f2fd;
    padding: 0 10px;
}

.wrapper{
    border-radius: 20px;
    background: #141414;
    padding: 35px 40px;
}

.wrapper header{
    color: #b2b2b2;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

header h2{
    font-size: 1.6rem;
}

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

header .column span{
    font-weight: 500;
    margin-right: 15px;
    font-size: 1.19rem;
}

.volume-slider input{
    outline: none;
    accent-color: #fff;
}

.keys-checkbox input{
    width: 60px;
    height: 30px;
    border-radius: 30px;
    cursor: pointer;
    appearance: none;
    background: #4b4b4b;
    position: relative;
}

.keys-checkbox input::before{
    content: "";
    position: absolute;
    background: #8c8c8c;
    height: 20px;
    width: 20px;
    border-radius: inherit;
    top: 50%;
    left: 5px;
    transform: translateY(-50%);
    transition: all 0.3s ease;
}

.keys-checkbox input:checked::before{
    left: 35px;
    background: #fff;
}

.piano-keys{
    display: flex;
    margin-top: 40px;
}

.piano-keys .key{
    cursor: pointer;
    list-style: none;
    color: #a2a2a2;
    text-transform: uppercase;
    position: relative;
    user-select: none;
}

.piano-keys .black{
    width: 44px;
    height: 140px;
    z-index: 2;
    margin: 0 -22px 0 -22px;
    border-radius: 0 0 5px 5px;
    background: linear-gradient(#333, #000);
}

.piano-keys .black.active{
    box-shadow: inset -5px 5px 10px rgba(255,255,255,0.1);
    background: linear-gradient(to bottom, #000 , #434343 );
}

.piano-keys .white{
    width: 70px;
    height: 230px;
    border-radius: 8px;
    border: 1px solid #000;
    background: linear-gradient(#fff 96%, #eee 4%);
}

.piano-keys .white.active{
    box-shadow: inset -5px 5px 20px rgba(0,0,0,0.2);
    background: linear-gradient(to bottom, #fff 0%, #eee 100%);
}

.piano-keys span{
    position: absolute;
    bottom: 20px;
    width: 100%;
    text-align: center;
    font-size: 1.13rem;
}

.piano-keys .key.hide span{
    display: none;
}

@media screen and (max-width: 815px) {
    .wrapper {
      padding: 25px;
    }
    header {
      flex-direction: column;
    }
    header :where(h2, .column) {
      margin-bottom: 13px;
    }
    .volume-slider input {
      max-width: 100px;
    }
    .piano-keys {
      margin-top: 20px;
    }
    .piano-keys .key:where(:nth-child(9), :nth-child(10)) {
      display: none;
    }
    .piano-keys .black {
      height: 100px;
      width: 40px;
      margin: 0 -20px 0 -20px;
    }
    .piano-keys .white {
      height: 180px;
      width: 60px;
    }
  }


@media screen and (max-width: 615px) {
    .piano-keys .key:nth-child(13),
    .piano-keys .key:nth-child(14),
    .piano-keys .key:nth-child(15),
    .piano-keys .key:nth-child(16),
    .piano-keys .key :nth-child(17) {
      display: none;
    }
    .piano-keys .white {
      width: 50px;
    }
  }