CSS Reset can be used contextually by appyling CSS Reset to specific regions of the page.
When CSS Reset is included in a page it applies rules to all HTML elements via type selectors like this: h1 {margin:0;}. The contextual version uses only descendent selectors like this: .yui3-cssreset h1 {margin:0;}. This means you can put that class value on a node in your document to choose which region(s) of your page CSS Reset will be applied to.
Everything within this container will have CSS Reset applied.
Because CSS examples are susceptible to other CSS on the page, this example is only available in a new window at the above link.