CHROME: Prevent jQuery slideDown() and prependTo() from moving whole screen

Question

I have the following code that prepends an li element to a ul list:

function prependListItem(entryHTML){
    $(entryHTML)
        .hide()
        .css('opacity',0.0)
        .prependTo('#container > ul')
        .slideDown('slow')
        .animate({opacity: 1.0})
}

The prepending works fine; however, I can't seem to prevent/stop the whole screen from moving/scrolling whenever the element is added.

Here is a demonstration of the issue: https://jsfiddle.net/byz7p69s/

Thank you in advance for any help!! Much appreciated :)