style.css

@import url("https://fonts.googleapis.com/css2?family=Roboto:wght@400;500&display=swap");
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Roboto", sans-serif;
}

body{
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh; /*viewport height). 100vh соответствует полной высоте вьюпорта. 1vh = 1% высоты вьюпорта*/
    padding:0 10px ;
    background-image: url("./tile1.png");
    background-repeat: repeat;
    /*background: #deebf9;*/
}
.wrapper{
    /*width: 780px; */
    border-radius: 15px;
    padding: 35px 40px;
    background: #0f0e0e; 
    background:linear-gradient(to top,#2e2e2e,#000);
}

.wrapper header{
    color:#dadada ;
    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{
    accent-color: #fff;
}

.keys-checkbox input{
    
    width: 50px;
    height: 25px;
    outline: none;
    cursor: pointer;
    position: relative;
    appearance:none;
    border-radius: 30px;
    background: #676767;
}

.keys-checkbox input::before{
    content: "";
    height: 20px;
    width: 20px;
    top: 50%;
    left:2px;
    border-radius: inherit;
    position: absolute;
    background:#a8a8a8;
    transform: translateY(-50%);
    transition: all 0.3s ease;
}

.keys-checkbox input:checked::before{
    left:28px;
    background:#fff;
}

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

.piano-keys .key{
    cursor: pointer;
    user-select: none;
    list-style: none;
    color:#9c9c9c ;
    position: relative;
    text-transform: uppercase;
}

.piano-keys .black{
    width: 44px;
    height: 140px;
    z-index: 2;
    margin: 0 -22px;
    border-radius: 0 0 5px 5px;
    background:linear-gradient(#434343,#000);
}

/*Added changes: .black:active pseudoclass => class .active */
.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 black ;
    background:linear-gradient(#fff 96%,#eee 4% );
}

/*Added changes: .white:active pseudoclass => class .active */
.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%;
    font-size: 1.14rem;
    text-align: center;
}

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

/* Make Piano responsive */
@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:where(:nth-child(13), :nth-child(14), :nth-child(15), :nth-child(16), :nth-child(17)) {
      display: none;
    }
    .piano-keys .white {
      width: 50px;
    }
  }