Center Header Image

I know this is probably really simple, but I can’t figure it out. I’ve uploaded a new image to my header and although I was able to move it all the way to the top, I can’t get it centered. Website is: https://www.awanderingsole.com.

My stylesheet has this:

#header {
height: 250px;
width: 100%;
}
#logo { margin: 0 }

#logo a {
/* background: url(images/logo.png) no-repeat; */
cursor: pointer;
position: absolute;
top: 0px;
display:block;
}

*Not sure what to add to make it centered. Thanks for looking!