yandex map lazy load

yandex-map-lazy.css

.ymap-container {
  position: relative;

  margin: 3em 0 2em 0;

  overflow: hidden;

  cursor: pointer;

  background: url('../img/yandex-before-load.jpg') #ffffff no-repeat;
  background-position: center center;
  background-size: cover;
  box-shadow: 0 0 2em  0 rgba(0,0,0,.2);
}

#map-yandex {
  position: relative;
  z-index: 7;

  width: 100%;
  height: 400px;
  cursor: pointer;
  background-color: transparent;
}
.loader {
  position: absolute;
  z-index: 15;
  top: -100%;
  left: 0;

  box-sizing: border-box;
  width: 100%;
  height: 100%;

  overflow: hidden;

  color: #000000;

  transition: opacity .7s ease;

  opacity: 0;
  background-color: rgba(0,0,0,.55);
}
.loader:after,
.loader:before {
  box-sizing: border-box;
}
.loader.is-active {
  top: 0;

  opacity: 1;
}

.loader-default:after {
  position: absolute;
  top: calc(50% - 24px);
  left: calc(50% - 24px);

  width: 48px;
  height: 48px;

  content: '';
  -webkit-animation: rotation 1s linear infinite;
          animation: rotation 1s linear infinite;

  border: solid 8px #ffffff;
  border-left-color: transparent;
  border-radius: 50%;
}

@-webkit-keyframes rotation {
  from {
    -webkit-transform: rotate(0);
            transform: rotate(0);
  }
  to {
    -webkit-transform: rotate(359deg);
            transform: rotate(359deg);
  }
}

@keyframes rotation {
  from {
    -webkit-transform: rotate(0);
            transform: rotate(0);
  }
  to {
    -webkit-transform: rotate(359deg);
            transform: rotate(359deg);
  }
}
@-webkit-keyframes blink {
  from {
    opacity: .5;
  }
  to {
    opacity: 1;
  }
}
@keyframes blink {
  from {
    opacity: .5;
  }
  to {
    opacity: 1;
  }
}