Switch to Inline Styles for Code Formatting

blog comments edit

Every once in a while I’ll be reading a blog entry and I’ll come across a place where someone has inserted a block of code. On the blog site, it looks like this:

Formatted code on a web

But in the RSS reader, it looks like this:

Formatting displayed incorrectly for code in an RSS

Not so great. I mean, the code is reasonably legible, but the style sheet renders literally in the reader. I shouldn’t see that CSS - it should be formatting the code, not appearing in the view window.

I also see RSS feeds that do display a nicely formatted block of code:

Code displaying correctly in

At first I thought it was a bug in my reader, so I tried some other readers and got the same result.

So what’s the difference?

The one that appears with the styles displayed literally in the feed uses an inline style sheet to do the formatting. Something like this:

    <pre class="csharpcode">
    <span class="kwrd">virtual</span> BOOL Paint(<span class="kwrd">int</span> button) = 0;
    <style type="text/css">
    .csharpcode, .csharpcode pre
    font-size: small;
    color: black;
    font-family: consolas, "Courier New", courier, monospace;
    background-color: #ffffff;
    .csharpcode .kwrd { color: #0000ff; }

While that sort of thing works well on a web site, it turns out that most RSS readers today don’t support inline style sheets.

The ones that look correct on the web site and in RSS use code like this:

    <pre style="background-color:#FFFFB9;;overflow: auto;"><div><span style="color: #000000; ">@Test
    </span><span style="color: #0000FF; ">public</span><span style="color: #000000; "> </span><span style="color: #0000FF; ">void</span><span style="color: #000000; "> emptyTest() {

Notice how the styles applied are actually inline on the tags, not styles from a style sheet. This sort of local style application is fairly widely supported in RSS readers. The drawback to this sort of style application is that not only is the HTML huge and horrible (usually it’s generated, and we all know how bad generated HTML gets), but if you want to change the look of the code on your site or in your RSS feed, there’s no simple way to do it.

Two recommendations for folks posting inline code snippets who want formatting and a good looking RSS feed:

If you’re going with a style sheet and not inline styles, move the style sheet to somewhere outside the actual entry being syndicated. Include it with a <link rel="stylesheet" type="text/css" href="http://url/to/your.css" /> line in the <head /> section of your site. By pulling it out of the entry proper, folks visiting your site will see the nice formatting, and at the very least the syndicated version will be legible and won’t include a bunch of clutter. On the other hand, it won’t look as pretty in RSS as it does on your site.

If you want people to see nicely formatted code on your site and in RSS, you’ll need to switch to the inline styles applied directly to tags. The Actipro CodeHighlighter control for ASP.NET does this (and there’s a Windows Live Writer plugin that uses it, so you don’t have to set it up on your site if you want to post through Windows Live Writer instead). The GeSHi (Generic Syntax Highlighter) project is a good PHP highlighter that can do either inline styles or use a style sheet. Check into a solution for your chosen platform that will let you apply the styles inline directly to tags.