Question: I came across some super-nice interactive textbook-style website which gently introduced the Fourier transform with many intuitive and interactive gra

Question: I came across some super-nice interactive textbook-style website which gently introduced the Fourier transform with many intuitive and interactive graphics. It was top-notch modern, with dynamic SVGs and looked excellent. This was about 6 months ago and I can't find the page anymore and I forgot to bookmark it. If this rings a bell, please share the link! Thanks!