Question

This is a duplicate from UI.StackExchange.com:
https://ux.stackexchange.com/questions/1004/mixing-percent-and-fixed-css

Should you ever apply percentage and fixed CSS together? Will it cause problems, and if so what kinds?

• Does mixing degrade browser render performance?
• Will mixing give you weird results on initial load with progressive rendering browsers?

Below is just a dumbed-down example of mixed usage, it could be any mixture. I am not looking for validation of the example. I have heard you should never do what I have in the example below, so I am trying to find out if using CSS in this manner is an issue.

Example mix usage:

<style>
.container
{
    width:300px;
}
.cell
{
    width:25%;
}
</style>

<table class="container">
     <tr>
        <td class="cell"><td>
        <td class="cell"><td>
        <td class="cell"><td>
        <td class="cell"><td>
     </tr>
</table>

Answer 1

+1 Good question. You may want to have a look at this article: “Fixed-width, liquid, and elastic layout” It goes over fixed width layout (em) and elastic layouts (%), and if you click to go to the next page it looks at ‘Elastic-liquid hybrid’ – where width: is set one way, with max-width: set the other. I know the article linked to above isn’t exactly what you asked, but it’s an example of mixed use within a single CSS style.

---

Edit: After some further reading I did find a quite a few contradictory opinions on the subject. I found several articles that held the idea that “you just can’t mix up pixels and percentages“. Though, for the most part, these sites were fairly dated. When I narrowed the search to only articles that have been put up within the past year, things changed a bit. There were still a few opinions against mixing, but they typically didn’t explain why, and seemed to of the “I always heard it was a bad idea” variety.
The majority of more recent information that I’ve found on the topic seems to indicate that mixing percentage with fixed widths is a perfectly acceptable practice, as long as it’s done with an understanding of the results.

see:

• “Fixed vs. Fluid vs. Elastic Layout: What’s The Right One For You?” (Jun 2009)
• “For A Beautiful Web: Changing Man Layout”
  …

Full Disclosure: I’ve been a mixer for many years, without really knowing whether my approach was ‘correct.’