I know it’s a silly little thing - but this is literally the most proud I’ve been of something I’ve designed. 🥲 A hover effect for links on my website. It has a blue underline without hover, and on hover the underline becomes a light background with border-radius, that gets a shadow and blurs the surrounding text.

(Notice the blur over the comma (only works in Firefox, though!), and the way the G pushes space for itself on return.)