I have a 700x300 background repeating seamlessly under the main content-div. Now I'd like to attach a div at the bottom of the content-div, containing a continuation-to-end of the background image, connecting seamlessly with the background above it.

Due to the nature of the pattern, unless the full 300px height of the background image is visible in the last repeat of the content-div's backround, the background in the div below won't seamlessly connect. Basically, I need the content div's height to be a multiple of 300px under all circumstances. What's a good approach to this sort of problem?

I've tried resizing the content-div on loading the page, but this only works as long as the content div doesn't contain any resizing, dynamic content, which is not my case:

function adjustContentHeight()
{
    // Setting content div's height to nearest upper multiple of column backgrounds height, 
    // forcing it not to be cut-off when repeated.

    var contentBgHeight = 300;
    var contentHeight   = $("#content").height();
    var adjustedHeight  = Math.ceil(contentHeight / contentBgHeight);

    $("#content").height(adjustedHeight * contentBgHeight);
}

$(document).ready(adjustContentHeight);

What I'm looking for there is a way to respond to a div resizing event, but there doesn't seem to be such a thing. Also, please assume I have no access to the JS controlling the resizing of content in the content-div, though this is potentially a way of solving the problem.

Another potential solution I was thinking off was to offset the background image in the bottom div by a certain amount depending on the height of the content-div. Again, the missing piece seems to be the ability to respond to a resize event.