no margin-bottom in bootstrap 3.0

by labanino

HTML

<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/bootstrap/3.0.3/css/bootstrap.min.css">
<script src="http://netdna.bootstrapcdn.com/bootstrap/3.0.3/js/bootstrap.min.js"></script>
<form action="/PerformanceExecution/ViewExecutionResults?class=form-horizontal" method="post">       
        <div class="form-group">
            <label for="inputEmail3" class="col-sm-4 control-label">Page:</label>
            <div class="col-sm-8">
                <select class="form-control" data-val="true" data-val-required="The Page field is required." id="Page" name="Page"><option value="">Choose an option</option>
<option value="HomePage">HomePage</option>
<option value="CommunityResults">CommunityResults</option>
<option value="CommunityDetails">CommunityDetails</option>
<option value="HomeDetails">HomeDetails</option>
</select>
            </div>
        </div>
        <div class="form-group">
            <label for="inputEmail3" class="col-sm-4 control-label">Market Id:</label>
            <div class="col-sm-8">
                <input class="form-control" data-val="true" data-val-number="The field MarketId must be a number." data-val-required="The MarketId field is required." id="MarketId" name="MarketId" type="text" value="">
            </div>
        </div>
        </form>