What Works
- Basic HTML5
- CSS2.1 + limited CSS3
- Flexbox (with prefixes on older WebKit)
@font-face (but don’t use — system font is faster)
- Simple JS (form submissions, basic DOM manipulation)
- HTTPS (required for some features)
What to Avoid
- Animations, transitions (ghosting on e-ink)
- Gradients (banding on 16-level grayscale)
- Drop shadows, blurs
- Web fonts (slow to load, use system serif)
- Heavy JS frameworks (React, Vue — too large)
- Images with fine detail (e-ink can’t render well)
- Dark backgrounds (e-ink inverts poorly, use #fff)
Kindle CSS Design Principles