CSS grid for custom theming in Omega? I cant find the answer to my question by googeling or in the documentation for the theme but im sure ive heard it exists. Does the Omega theme give you a CSS grid to work with? 

So if you wanted to customize a tpl file and have 2 colums, one twice the width of the other, could you just write some CSS a bit like this? 

&lt;div class="1of3"&gt;content here&lt;/div&gt;
&lt;div class="2of3"&gt;more content here&lt;/div&gt;


Im happy to use standard classes but Im trying to avoid adding additional CSS, I would have thought the theme (as a grid based layout) would have classes I could use? Thanks
Absolutely, one might argue that's one of the reasons to use Omega in the first place; as per the first two features listed on the project page:


Fully Responsive Grid layouts based on 960.gs standards.
12, 16, 24 Column Layouts built in.


Have a look in the CSS files with names like alpha-default-normal-12.css under omega/alpha/css/grid/alpha_default/* to discover what classes are available for you to use. 

Those files should make it fairly obvious what conventions Alpha/Omega use for naming those classes too, so you should be able to predict what you need to use easily.