Controls
- drag rectangle zoom (release to zoom)
- shift+drag / right-drag pan, flick for momentum
- wheel zoom toward cursor
- click on Mandelbrot → open Julia set for that c
- J toggle Julia · M back to Mandelbrot
- ← ↑ → ↓ pan · + − zoom · 0 reset
- B history back · 1–4 palette
- A color drift · S bookmark · H help
- hover (Mandelbrot) → live Julia preview + reticle