Change the width property of: before the CSS selector by using JQuery


I have a page that has an image in it and I styled it using :before CSS selectors.
The image is dynamic so it hasn't a fixed width; So I need to set :before rule's width dynamically.
I want do it in client side using JQuery.
Assume this:

    width: 300px;
    float: left;
    content: "";
    height: 430px;

    width: 500px;
    float: right;
    padding: 5px;
    overflow: hidden;
    text-align: justify;

How Can I only change the width property of class with :before selector (and not one without it) using JQuery?

I don't think there's a jQuery-way to directly access the pseudoclass' rules, but you could always append a new style element to the document's head like:

$('head').append('<style>.column:before{width:800px !important;}</style>');

See a live demo here

I also remember having seen a plugin that tackles this issue once but I couldn't find it on first googling unfortunately.