<style>

	.a{border:1px solid red;height:50px;}

	.b{border:1px solid blue;float:left;}

	.c{border:1px solid green;float:left;}

</style>

<div class="a">

	<div class="b">bbbbbbbbbbbbbbbbb</div>

	<div class="c">ccccccccccccccccc</div>

</div>

<style>

    .a{border:1px solid red;height:50px;}

    .b{padding-left:12px;padding-right:12px;border:1px solid blue;}

    .c{border:1px solid green;float:left;}

    .d{width:300px;margin:0 auto;}

    .b,.c{text-align:center;}

</style>

<div class="a">

<div class="d">

    <div class="b">bbbbbbbbbbbbbbbbb</div>

    <div class="c">ccccccccccccccccc</div>

</div>

</div>