I was designing and building a portfolio page for a photographer. He mostly does black & white portraits with either a white or black background so I had the idea of splitting the page into a light and dark side (Star Wars joke definitely intentional).
I worked waaay too long on a *diagonal* CSS wipe animation when the user switches sides and I was quite proud of it.
Half a year later we realize that basically no one has noticed the switch button. Analytics confirmed it was less than 4% of visitors. 🤦‍♂️