Hello everybody! Someone of you know how to center the screen as well as I show you the code. Will you help me to use a style sheet properly in the center please?

<style type="text/css">
#quote { /*style for quote division*/
position:relative;
width:375px;
height:70px;
border:1px solid black;
font-family:sans-serif;
font-size:95%;
padding:3px;
background-color:lightyellow;
}
#auth { /*style for quote author, if any*/
position:absolute;
bottom:3px;
right:10px;
}
</style>