content_save_prefilter to add the 'u-featured' class to the first image in a post - the proposed microformats2 markup for the featured image.
# Just setting up my micro.blog
# Latte at lunch.
# With or without Micro.blog, I'm now totally devoted to self-hosted microblogging. The last few months have completely reinvigorated my blog and prompted me to learn so much.