carousel height and width wont change - html

Question

hi so this is the code
<div id='mai'>
<div class="jumbotron">
<div class="container">
<div id="carousel-example-generic" class="carousel slide" data-ride="carousel">
<!-- Indicators -->
<ol class="carousel-indicators">
<li data-target="#carousel-example-generic" data-slide-to="0" class="active"></li>
<li data-target="#carousel-example-generic" data-slide-to="1"></li>
<li data-target="#carousel-example-generic" data-slide-to="2"></li>
</ol>
<!-- Wrapper for slides -->
<div class="carousel-inner" role="listbox">
<div class="item active">
<img src="img/2.jpg" alt="">
<div class="carousel-caption">
...
</div>
</div>
<div class="item">
<img src="img/3.jpg" alt="">
<div class="carousel-caption">
...
</div>
</div>
...
</div>
<!-- Controls -->
<a class="left carousel-control" href="#carousel-example-generic" role="button" data-slide="prev">
<span class="glyphicon glyphicon-chevron-left" aria-hidden="true"></span>
<span class="sr-only">pre</span>
</a>
<a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next">
<span class="glyphicon glyphicon-chevron-right" aria-hidden="true"></span>
<span class="sr-only">nx</span>
</a>
</div>
</div>
</div>
</div>
<h3>Example heading <span class="label label-default">New</span></h3>
<div class="row">
<div class="col-sm-6 col-md-4">
<div class="thumbnail">
<img src="img/4.jpg" alt="..">
<div class="caption">
<h3>برنده لوح تقدیر</h3>
<p>...</p>
<p>Button Button</p>
</div>
</div>
</div>
<div class="col-sm-6 col-md-4">
<div class="thumbnail">
<img data-src="holder.js/300x300" alt="...">
<div class="caption">
<h3>Thumbnail label</h3>
<p>...</p>
<p>Button Button</p>
</div>
</div>
</div>
<div class="col-sm-6 col-md-4">
<div class="thumbnail">
<img data-src="holder.js/300x300" alt="...">
<div class="caption">
<h3>Thumbnail label</h3>
<p>...</p>
<p>Button Button</p>
</div>
</div>
</div>
</div>
i tried to change the height and width with class mai , but it wont change my carousel div height and it will broke my thumbnails and brings them upward towards the main carousel ...
what should i do ????