Remove white padding above header on desktop

Site URL: http://www.amosbeck.com

Hi, I was making some changes to my website last night and realized that, at some point, I now have what seems to be some white padding above my header. I'm not sure if I have accidentally enabled this in the design section of the template but I've adjusted about every setting and can't seem to identify where it's come from or how to eliminate it. It also only appears on desktop, appears on all my web pages, but ISN'T on mobile. Anyone know where I should look to remove this padding? Or, at least, adjust the color so it matches if I cannot remove it? I don't have a business subscription, so my code injection for my header hasn't been modified from the default.

Try adding to Design > Custom CSS

header#header {
    margin-top: 0;
}