I would like to have the same margin on top and bottom.
My container div looks like:
<div id="search">
    <input id="txtSearch" type="txt">
</div>
My CSS looks like:
#search{
    min-width: 25%;
}
#txtSearch{
    display: block;
    width: 80%;
    height: 60%;
    margin: 0 auto;
    }
For further information please have a look at my JSFIDDLE
 
    