`mx-auto` sets left and right margins to 'auto'. If an element is block-level and has no explicit width, it will try to take up the full available width of its parent. In this case, `mx-auto` won't visually center it because there's no remaining space to distribute as margins.
Block with `mx-auto` but NO `w-` or `max-w-` class.
This element appears full-width because block elements naturally expand to their container's width if no width is specified. `mx-auto` has no visible centering effect here.
Block with `w-1/2` AND `mx-auto`.
This element has a defined width (`w-1/2`), so `mx-auto` can distribute the remaining horizontal space equally, centering the element.