Make div 100 height of browser window. Hi, I have a parent div with height: auto.So what I want to do is make loader have width and height 100 of the parent div, so everything behind is hidden. how do you give the parent element the height of / CSS - 100 Remaining Height Of Parent Div - Free CSS Tutorials, Help, Tips, Tricks, and More. How to make a floated div 100 height of its parent? expand child div within parent div (width:100) firefox which is the standard for css. How can I force it to be 100 of the height of the parent div?For outer height to be based on its content, and have inner base its height on that, make both elements absolutely positioned.