Setting Inner Div Width's Percentage Of Parent

I have 2 parent div's. (parent-left and parent-right). Parent left is 50px and parent right takes up remaining screen width, so I set it to 100%. I have 2 child/inner divs within p

Solution 1:

Do not set a width for the #parent-right element, instead set a left-margin equal to the width of the #parent-left element.

<div id='parent-right' style="margin-left:50px;">

Demo at http://jsfiddle.net/gaby/5J38g/