Simplify installation process.

[Md Hasanuzzaman]

You can simplify your installation process by passing the background image with the section. Something like

<div class="slim-prx" data-bg="bg.jpg">
    <div class="container">
            content
    </div>
</div>

And including required css in js file.

[Sajidur Rahman]

We want to keep markup as clean as possible. So I see no point defining background on data attribute. :)