Expand a div to fill the remaining width

I just discovered the magic of flex boxes (display: flex). Try this: <style> #box { display: flex; } #b { flex-grow: 100; border: 1px solid green; } </style> <div id=’box’> <div id=’a’>Tree</div> <div id=’b’>View</div> </div> Flex boxes give me the control I’ve wished css had for 15 years. Its finally here! More info: https://css-tricks.com/snippets/css/a-guide-to-flexbox/