Put spacing between divs in a horizontal row?

Question

I have 4 divs in a horizontal row. I want to put space between the divs (using margin, I guess?), but the divs overflow their parent container when I do that.

With zero margin, they line up nicely on one line:

<div style="width:100%; height: 200px; background-color: grey;">
  <div style="width: 25%; float:left; margin: 0px; background-color: red;">A</div>
  <div style="width: 25%; float:left; margin: 0px; background-color: orange;">B</div>
  <div style="width: 25%; float:left; margin: 0px; background-color: green;">C</div>
  <div style="width: 25%; float:left; margin: 0px; background-color: blue;">D</div>
</div>

Now when I introduce a margin of 5px, the last button wraps:

<div style="width:100%; height: 200px; background-color: grey;">
  <div style="width: 25%; float:left; margin: 5px; background-color: red;">A</div>
  <div style="width: 25%; float:left; margin: 5px; background-color: orange;">B</div>
  <div style="width: 25%; float:left; margin: 5px; background-color: green;">C</div>
  <div style="width: 25%; float:left; margin: 5px; background-color: blue;">D</div>
</div>

I guess this is because the width attribute, when a percentage, doesn't take the margin into account for the element's total width? What's the right way to do this?

Thanks

Answer 1

A possible idea would be to:

1. delete the width: 25%; float:left; from the style of your divs
2. wrap each of the four colored divs in a div that has style="width: 25%; float:left;"

The advantage with this approach is that all four columns will have equal width and the gap between them will always be 5px * 2.

Here's what it looks like:

.cellContainer {
  width: 25%;
  float: left;
}

<div style="width:100%; height: 200px; background-color: grey;">
  <div class="cellContainer">
    <div style="margin: 5px; background-color: red;">A</div>
  </div>
  <div class="cellContainer">
    <div style="margin: 5px; background-color: orange;">B</div>
  </div>
  <div class="cellContainer">
    <div style="margin: 5px; background-color: green;">C</div>
  </div>
  <div class="cellContainer">
    <div style="margin: 5px; background-color: blue;">D</div>
  </div>
</div>

Answer 2

I would suggest making the divs a little smaller and adding a margin of a percentage.

<div style="width:100%; height: 200px; background-color: grey;">
  <div style="width: 23%; float:left; margin: 1%; background-color: red;">A</div>
  <div style="width: 23%; float:left; margin: 1%; background-color: orange;">B</div>
  <div style="width: 23%; float:left; margin: 1%; background-color: green;">C</div>
  <div style="width: 23%; float:left; margin: 1%; background-color: blue;">D</div>
</div>

http://jsfiddle.net/YJT7q/