This is not exactly philosophical, but is practical.
I use Firefox as my primary browser. If you aren’t, you should be. I have found that sometimes WordPress and other sites display rather badly in Firefoox. The best way to describe it is that the sites look like they have been warped back in time to the early 1990s.
Using the Web Developer plug in for Firefox (the Validate CSS tool to be precise) I found two errors in the CSS for WordPress. I used IE to check the pages and they looked fine. Thus, I inferred the problem was on my end and with Firefox. Since the problem was intermittent and also occurred on my office PC, I inferred it had to be something that changed on both computers. The logical candidate was something that Firefox stored but also could be removed/change. This lead me to the Clear Private Data option in the Tools menu of Firefox. I did that (use the default) and it worked fine. My guess would be that it was a cache issue.