class attributes is not reflected in the DOM

[ivanceras]

I checked and played around the master branch, but it seems attributes like class is not reflected on the dom element therefore styling the dom is not working.
The weird thing is that that attribute like type and accept works.
i.e

<input type='file' accept='txt'/>

It gets reflected into the DOM.
I set all of the attributes using with something like

div((
   input((
        attributes[
                ("class", Str("pretty"), 
                ("type", Str("file")), 
                ("accept", Str("txt"))
           ]
   ))
))

I've tried going through the code, but still has no idea why it behaves like that.
PS: I've tried it on div, nav, ul, with same behaviour.

[ivanceras]

I just realize that attributes are set programmatically in javascript, so class will be className,

z-index will be zIndex etc.