The theme of a WordPress blog is like its skin, its graphical interface… So the theme is part of the blog’s identity.
Should that identity be preserved across platforms, even when some of the platforms are mobile? A recent post suggests that it typically isn’t. WordPress.com’s mobile default is a mobile theme, rather than a mobile version of the blog’s “main” theme.
For self-hosted WordPress, there are several plugins available. The most popular seem based on the rule: if mobile platform, then mobile theme.
There are some aspects of theme design that don’t translate well to mobile. For example, the theme for this blog shows a lot of white space. That doesn’t work on mobile, when there isn’t much space to spare.
On the other hand, colors do work on mobile. The WordPress.com CSS upgrade doesn’t let me tweak the color scheme of the mobile themes. I wish it did.
For self-hosted blogs, it might be good practice to have a little CSS file that specifies colors, and other aspects of themes that carry over well to mobile, and invoke that file from every theme the blog uses.
I’m sure someone has written a good, thoughtful account of aspects of theme design, and the extent to which each aspect should be similar or different between mobile and other themes. If you know of it, please leave a link in the comments.