Bootstrap solution:
https://jsfiddle.net/e76tknpq/
<div class="row">
<div class="product col-md-4 col-lg-4 col-sm-4 col-xs-4"></div>
<div class="product col-md-4 col-lg-4 col-sm-4 col-xs-4"></div>
<div class="product col-md-4 col-lg-4 col-sm-4 col-xs-4"></div>
</div>
<div class="row">
<div class="product col-md-4 col-lg-4 col-sm-4 col-xs-4"></div>
<div class="product col-md-4 col-lg-4 col-sm-4 col-xs-4"></div>
<div class="product col-md-4 col-lg-4 col-sm-4 col-xs-4"></div>
</div>
<div class="row">
<div class="product col-md-4 col-lg-4 col-sm-4 col-xs-4"></div>
<div class="product col-md-4 col-lg-4 col-sm-4 col-xs-4"></div>
<div class="product col-md-4 col-lg-4 col-sm-4 col-xs-4"></div>
</div>
CSS
.product:nth-child(even){
background: red;
height:180px;
}
.product:nth-child(odd){
background: green;
height:180px;
}