Drag Handle to Resize Canvas

I like to make fluid, mobile first websites. However, when using Oxygen, I can not design this way visually, because the side bars do not pull out far enough to see the design at smaller sizes. This forces me to use screen size breakpoints, which then adds the styles to a media query, which is not what I want. https://www.facebook.com/groups/2805386309772446/posts/3586460074998395/