Help needed to Center Header Image

I’ve been at this for a few days with no luck. How do I center this clickable header image?

My style.css:

#header {

	background: #fff;

	margin: 0 ;

	padding: 0px 0 0 40px ;

	height: 182px;
	width: 640px;
	position: fixed; 

	}

#headerimg {

	margin: 0 0 0 60px;

	height: 182px;

	padding: 0 0 0 0px;

	}

My header.php:

<div id="header">

	<div id="headerimg">

		<a href="<?php bloginfo('url'); ?>">
		<div align="center" style="width:100%;top:0;left:0;position:absolute;">
 	 	<h1><img src="https://www.polypowwow.com/modasuki/wp-content/themes/minimalism/images/Modasukibanner3.jpg" alt="<?php bloginfo('name'); ?>" /></h1>
    </a>

</div>