It’s different for each browser, so:
- Firefox (Gecko): https://dxr.mozilla.org/mozilla-central/source/layout/style/res/html.css. Or, browse to
resource://gre-resources/
and look athtml.css
. - Chrome/Safari (WebKit): http://trac.webkit.org/browser/trunk/Source/WebCore/css/html.css
- Internet Explorer (Trident), older versions: http://web.archive.org/web/20170122223926/http://www.iecss.com/
You can also look at the HTML5 Boilerplate stylesheet, which “normalizes the display of a lot of stuff without being a reset in the traditional sense”. It also fixes quite a few bugs/inconsistencies.
It’s also worth looking at: https://github.com/necolas/normalize.css/blob/master/normalize.css