No-Library (pure JS), HTML, CSS, JavaScript
Mootools 1.4.1, HTML, CSS, JavaScript
jQuery 1.10.1, HTML, CSS, JavaScript
jQuery 1.11.0, HTML, CSS, JavaScript
jQuery 2.1.0, HTML, CSS, JavaScript
Some browsers render the viewport's default scroll bar in the body element (Chrome, Safari), others in the html element (Firefox, IE). Animating the scrollTop property on an element which has no scroll bar has no effect, as you may have noticed.