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CSS CSS Basics (2014) Basic Layout Floats

Float Vs. Flex. Can't center 3 floated items.

Hello Treehouse community, I need help regarding one topic.

I am playing around trying to center 3 floated elements. Although I can probably do it with 2 single elements, I am unable to do add space in between when I float 3 elements.

Let's get to the point. This is how I center 3 elements using the flex technique. For your convenience, I created a Code Pen:


This is the same structure, trying to float 3 centered elements with space in between:


When I add some margin, left or right, to the ".box" element, the structure breaks. Even if I add 1px boarder as well.

If I substitute the "width" from a percentage value to a pixel value, the boxes get stacked together to the left.

.box {
 width: 200px;
 float: left;

Any ideas on how to center those elements with space in between? What are the benefits of a technique versus the other?

Thanks for your support.

Kind regards, Alex

1 Answer

Steven Parker
Steven Parker
227,114 Points

You can add borders to your column boxes, but you must use a different sizing model to prevent overflowing the total width:

.box {
  width: 33.33%;
  float: left;
  box-sizing: border-box;    /* make borders count as part of the width */
  border: 20px solid white;

Unfortunately, there is no "margin-box" sizing model, so if you want to add margins you must compensate for them by reducing the percentage width.

I think you have already demonstrated how flexbox is a far superior technique to floats for creating column layouts.

Hello Steven,

Thanks for your response!

I completely forgot about the "border box" property, thanks for that! I managed to "center" (it looks totally wonky) the 3 columns, here's an update: https://codepen.io/DeMichieli/pen/qvJYaM?editors=1100#0

I had to break the code for 3 different boxes instead of having one selector for all of them.

Thanks, Alex

Steven Parker
Steven Parker
227,114 Points

So "border-box" doesn't help for the margins, but the "calc" function could be used to accurately compensate for them:

.box1 {
  width: calc(33.33% - 20px);
  margin: 0 10px;

Happy coding!