How to set up display properties for a crosstab is CSS?

I am woundring how to setup css class and code like in this tutorial.

myalerting.css ?

Set up display properties for a crosstab: Design Studio 1.2 - YouTube.

Design Studio 1.2: Set up display properties for a crosstab

if you have sample file please share I am sure other can be befits from as well.

I would like to use color display on numbers or icons in seperate column if the value in certain range  or a value is below or avove business needs.

Thanks.