HTML

<div class="loader">
  <div class="square" ></div>
  <div class="square"></div>
  <div class="square last"></div>
  <div class="square clear"></div>
  <div class="square"></div>
  <div class="square last"></div>
  <div class="square clear"></div>
  <div class="square "></div>
  <div class="square last"></div>
</div>

SCSS CSS LESS

$squarew: 15px;
$squareh: 15px;
$squaremargin: 5px;
$loaderw: $squarew * 3 + $squaremargin *2;
$loaderh: $squareh * 3 + $squaremargin *2;
$delayenter: 0.3s;
$topenter: -10px;

@mixin transition($value) {
  -webkit-transition: $value ;
   -moz-transition: $value ;
          transition: $value ;
}

@mixin delay( $delay ) {
  -webkit-animation-delay: $delay;
   -moz-animation-delay: $delay;
  animation-delay: $delay;
}
@-webkit-keyframes enter{
  0%   { 
    opacity: 0;
    top: $topenter;
  }
  5%   { 
    opacity: 1;
    top: 0px;
  }
  50.9% { 
    opacity: 1;
    top: 0px;
  }
  55.9% { 
    opacity: 0;
    top: - $topenter;
  }
}
@keyframes enter{
  0%   { 
    opacity: 0;
    top: $topenter;
  }
  5%   { 
    opacity: 1;
    top: 0px;
  }
  50.9% { 
    opacity: 1;
    top: 0px;
  }
  55.9% { 
    opacity: 0;
    top: - $topenter;
  }
}
@-moz-keyframes enter{
  0%   { 
    opacity: 0;
    top: $topenter;
  }
  5%   { 
    opacity: 1;
    top: 0px;
  }
  50.9% { 
    opacity: 1;
    top: 0px;
  }
  55.9% { 
    opacity: 0;
    top: - $topenter;
  }
}


body{ background: #1fbeca; }
*{  margin: 0;}

.loader{
  position: absolute;
  left: 50%;
  top: 50%;
  margin-left: - $loaderw / 2;
  margin-top: - $loaderh / 2;
}
.square{
  background: white;
  width: $squarew;
  height: $squareh;
  float: left;
  top: $topenter;
  margin-right: $squaremargin;
  margin-top: $squaremargin;
  position:relative;
  opacity: 0;
  -webkit-animation: enter 6s infinite;
  animation: enter 6s infinite;
}
.enter{
  top: 0px;
  opacity: 1;
}
.square:nth-child(1){
  @include delay(6 * $delayenter);
}
.square:nth-child(2){
 @include delay(7 * $delayenter);
}
.square:nth-child(3){
  @include delay(8 * $delayenter);
  background: #fdc96f;
}
.square:nth-child(4){
  @include delay(3 * $delayenter);
}
.square:nth-child(5){
  @include delay(4 * $delayenter);
}
.square:nth-child(6){
  @include delay(5 * $delayenter);
}
.square:nth-child(7){
  }
.square:nth-child(8){
  @include delay(1 * $delayenter);
}
.square:nth-child(9){
  @include delay(2 * $delayenter);
}
.clear{
  clear: both;
 }
.last{
   margin-right:0;
}