RapidWeaver Stacks add-on info:
With the PageScale Stack you can scale your entire RapidWeaver Stacks page – in preview and/or edit. You can also just choose to scale a div.
Being able to scale you're entire page in Edit is sometimes nice when you need to copy-paste Stacks from top to bottom of your crowded RapidWeaver page.
You can scale your page in 10% steps from 10% to 200%.
RapidWeaver, stacks, responsive, free stack.