How to set z index for web components

Am designing a social website and i need to know to make z index work properly for div components to work with floating components like chat box in website, without inter fearing with other div components in website.

I prefer to use css base methods, please advice...

Thanks.

z-index doesn't work on floats. you can however add a position: relative as well for you css in combination to float: left and then the z-index should kick in.

Do you have a link to your page?