When you launch a new site or push out a new version of your web page, did you check how your site looks in both IE and Firefox? If you haven’t, you should now. If you have been reading the posts here, you’ll know that Firefox has a fairly significant browser market share, and it is actually gaining on IE.
It is a known issue that IE and Firefox can render differently. Sometimes the difference is minor: An extra line feed here, a different shade of blue there. You might not like it, but it doesn’t really affect the user experience. However, there can cases where the difference is more pronounced, for example, columns designed to be next to each other now could become one on top of the other. In these cases, your visitors will leave as soon as they enter your site.
This has implications in SEO. Lost visitors means your site is missing out on possible additional links as well as possible repeat visits. Also, search engines know what visitors click on and how long they stay there. Well, maybe not always how long they stay on a site, but if a visitor clicks on a search result to go to site A, and 3 seconds later that visitor clicks on a different search result from the same query, it doesn’t take a sophisticated algorithm for search engines to see that site A isn’t attractive to users. Over time, site A’s rankings will suffer.
So, do yourself and your visitors a favor, and make sure you check how your site renders in both Firefox and IE.