Centering a Placeholder and Input Text in a Text Field

I was wondering if it was possible to center a placeholder and the input which the user will enter in the Text Field. I imagine it would be possible yet I cant figure it out. could anyone help? my code for the Text Field in question is below...

<input type="text" style="font-weight:bold:" name="kword" id="kword" autofocus ="on" placeholder="Enter Keyword(s)" autocomplete ="on"/>

Thanks