For example, the child may flow out of the parent boundary or it may not get upto 100% height that you will see in your browser output.Example 1: This example makes a child flex-box of height 100% using CSS. How can I make Bootstrap columns all the same height? So, if your element is inside another element that has a height of 100px, and you set the child element's height to 100%. Why did the Soviets not shoot down US spy satellites during the Cold War? For height: 100% to work, "container" needs to have an explicit height set. You could do something like the equal height column trick. Here it goes: Simple example. Thanks for the reminder. How to define one or more header cells a cell is related to in HTML ? I'll assume (b)if that is so, I don't think you will be able to do it given your current page structure (at least, not with pure CSS and no scripting). By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. looks like you are looking for sticky footer somehow.You can achieve what you are looking for using display properties used by