How do you center a block element using CSS?

To center a block element using CSS, setting the width of the element and applying margin: auto; is the correct approach. This method works because when a block element has a defined width, the browser will calculate the available space on either side of the element and distribute it equally when the margins are set to auto. This effectively centers the block element horizontally within its parent container.

In contrast, using padding: auto; does not achieve the same result because padding adds space inside the element itself rather than adjusting its position with respect to its container. The option involving margin: center is incorrect because there is no margin property with that value; margins can only take specific units or auto values. Lastly, setting the display to inline doesn’t apply to block elements, as inline elements do not respect width properties and cannot be centered in the same way. Instead, they flow within the content and are aligned according to text.