Tell me more about the rendering stages: layout (reflow) and paint (repaint)

The rendering process in the browser involves several stages, among which layout (reflow) and paint (repaint) are important.

• Layout (reflow) — the stage where the browser calculates the sizes and positioning of all elements on the page. If dimensions, content, or styles affecting geometry change, a re-calculation of element placement occurs.

• Paint (repaint) — the stage where the browser draws pixels on the screen, rendering colors, text, shadows, and other visual effects. If properties affecting appearance but not size change (e.g., text color), a repaint occurs without reflow.

Avoiding frequent reflows and repaints is important for performance, as reflow is more costly. For example, changing the width property will cause a reflow, while changing the color property will only cause a repaint.