Display: Block Inside Display: Inline

While the question poses the scenario of a display:block element within a display:inline parent, the fundamental question is about the differences between these two display values in such a scenario.

According to the CSS 2.1 specification, when an inline element contains a block element, the inline box is broken around the block. Anonymous block boxes are created around the inline content before and after the block, and the block becomes a sibling of these anonymous boxes.

This results in a structure where the parent element, even though it is defined as display:inline, behaves differently due to the presence of the display:block child. The parent element effectively becomes a block box containing anonymous block boxes.

Differences Between Display: Inline and Display: Block Parent

Despite the similarity in structure, there are subtle differences between display:inline and display:block parent elements in this scenario:

• Content Flow: Inline elements flow horizontally with text, while block elements flow vertically. The anonymous block boxes created around the inline parent allow for vertical stacking of child elements, simulating block behavior.
• Anonymous Block Box Generation: Display:inline causes anonymous block boxes to be generated for the inline content adjacent to the block child. This is not the case with a display:block parent, where the entire parent element becomes a block box.
• Border Treatment: The CSS 2.1 specification notes that certain properties, such as border, still apply to elements that generate anonymous block boxes. Therefore, a display:inline parent with a border will have the border drawn around the anonymous block boxes, creating an open border at the line breaks. In contrast, a display:block parent with a border will have a closed border around the entire block box.
• Text Wrapping: Inline elements naturally wrap text around them. In this scenario, the anonymous block boxes surrounding the inline content prevent text from wrapping around the block child, as if the parent were a display:block element.