* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html, body {
  width: 100%;
  height: 100%;
}

.js-bg {
  position: relative;
  width: 100%;
  height: 500px;
  border: 1px solid #000;
}

.shape--circle {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background: rgba(0,0,0,0.5);
}

.js-bg-item {
  position: absolute;

  opacity: 0;
  -webkit-transition: transform 1s ease 0s, opacity 1s ease 0s; 
  transition: transform 1s ease 0s, opacity 1s ease 0s
}

.js-bg-item.js-active {
  opacity: 1;
  -webkit-transform: scale(0.6);
  transform: scale(0.6);
  -webkit-transition: transform 1s ease 0s, opacity 1s ease 0s; 
  transition: transform 1s ease 0s, opacity 1s ease 0s
}

.js-bg-item.js-current {
  opacity: 1;
  -webkit-transform: scale(1.6);
  transform: scale(1.6);
  -webkit-transition: transform 1s ease 0s, opacity 1s ease 0s; 
  transition: transform 1s ease 0s, opacity 1s ease 0s
}