* {
  font-family: Arial, Helvetica, sans-serif;
  box-sizing: border-box;
}
body { background-color: rgb(51, 51, 51); }
#AudioPlayer { width: 100%; }
#header { 
  margin-right: 30px;
  /* border: 1px solid white; */
  align-items: center;
  float: right;
  display: flex;
  }
#header .icon {
margin-left: 10px;

}
#demoList { margin-top: 10px; }
#demoList .song {
  padding: 10px;
  color: #9f9f9f;
  border-bottom: 1px solid #d3d3d3;
  cursor: pointer;
  display: flex;
  align-items: center;
}
#demoList .song:first-child {
  border-top: 1px solid #d3d3d3;
}
#demoList .song.now {
  color: #fff;
  background: #515151;

}
#demoList .song_thumb img {
  transition: 300ms opacity;
  width: 30px;
  height: 30px;
  display: block;
}
#demoList .song_thumb {
  position: relative;
  margin-right: 10px;
  background-color: black;
}
#demoList .song_thumb svg {
  transition: 300ms opacity;
  opacity: 0;
  position: absolute;
  width: 24px;
  top: 50%;
  left: 50%;
  margin-top: -12px;
  margin-left: -12px;
  /*fill: #fff;*/
  stroke: #fff;
}
#demoList .song:hover .song_thumb svg {
  opacity: 1;
}
#demoList .song:hover .song_thumb img {
  opacity: 0.5;
}
@media screen and (min-width: 1025px) {
  .w3-card-4 {
    margin: auto; 
    width: 100%; 
    border: 3px solid #222; 
    padding: 10px;
  }  
}
@media screen and (max-width: 1024px) {
  .w3-card-4 {
    padding: 10px;
    box-shadow: none;
  }  
}
.song_vu {
  display: block;
  width: 30px;
  height: 30px;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  opacity: 0;
  position: absolute;
  top: 0;
  left: 0;
  z-index: 2;
  background: #515151;
}

.song_vu span {
  display: block;
  width: 3px;
  height: 20px;
  background: #fff;
  margin: 0 1px;
  transform-origin: bottom;
}

body.audio-playing .song.now .song_vu {
  opacity: 1;
}

.song_vu span:nth-child(1) {
  animation: vuBounce1 1000ms infinite;
}

.song_vu span:nth-child(2) {
  animation: vuBounce2 1000ms infinite;
}

.song_vu span:nth-child(3) {
  animation: vuBounce3 1000ms infinite;
}

.song_vu span:nth-child(4) {
  animation: vuBounce4 1000ms infinite;
}

.file-image {
  position: relative;
  background-color: #000;
}

.file-image svg {
  opacity: 0;
  display: block;
  position: absolute;
  width: 80px;
  height: 80px;
  margin: -40px 0 0 -40px;
  top: 50%;
  left: 50%;
  z-index: 2;
  pointer-events: none;
}

body:not(.audio-playing) .file-image img {
  opacity: 0.5;
}

body:not(.audio-playing):has(.song.now) .file-image svg {
  opacity: 1;
  pointer-events: all;
}

@keyframes vuBounce1 {
  0% {
    transform: scale(1, 0);
  }
  20% {
    transform: scale(1, 0.5);
  }
  50% {
    transform: scale(1, 1);
  }
  100% {
    transform: scale(1, 0);
  }
}

@keyframes vuBounce2 {
  0% {
    transform: scale(1, 0);
  }
  75% {
    transform: scale(1, 1);
  }
  100% {
    transform: scale(1, 0);
  }
}

@keyframes vuBounce3 {
  0% {
    transform: scale(1, 0);
  }
  25% {
    transform: scale(1, 0);
  }
  75% {
    transform: scale(1, 1);
  }
  100% {
    transform: scale(1, 0);
  }
}

@keyframes vuBounce4 {
  0% {
    transform: scale(1, 0);
  }
  80% {
    transform: scale(1, 1);
  }
  100% {
    transform: scale(1, 0);
  }
}