How does the browser decide when to reflow the layout on a page?

Example Concept: Reflow is a process where the browser recalculates the positions and sizes of elements on a webpage. This occurs when changes are made to the DOM, such as adding or removing elements, changing element styles, or resizing the browser window. Reflow can be triggered by JavaScript operations that modify the DOM or CSS properties that affect layout, like width, height, margin, and padding.