How to Set up the 100% Height Widget
Drag a rectangle onto your canvas inside Muse. You can style your rectangle and place it wherever you want on the page, however, the top of the rectangle must be touching the top of the canvas inside Muse.
Open up your Library panel inside Muse and drag the 100% Height Enabler widget onto the canvas.
With your rectangle selected, open up your Graphic Styles panel and assign a new graphic style to the rectangle. You can call your graphic style what ever you want, in this example I am naming this 'height.'
Open up your widget Options panel for the 100% Height Enabler widget and locate the field named 'Graphic Style Name.' In this field enter the name of your graphic style.
You can now preview this page in your browser and the rectangle will now be displaying 100% height! Please note that you cannot set this rectangle to 100% width and 100% height.