I have a pair of section elements identified as container1 and container2 respectively. Both contain a ul element as their first child. The section with the id container1 has a border.
- When a margin is applied to the ul elements, in the case of section#container1 (with a border), the margin appears inside the container. However, for section#container2 where there are no children before the ul element, the margin is outside the container.
- This phenomenon occurs with any first child of a parent when the parent's dimensions are not specified.
Here is the link to the jsbin page. And here is the screenshot of the page.
If the height or width of a parent block element is not defined, any margin set for the first child is treated as if it were set for the parent itself.
However, when a border is present, the margin is placed inside the parent container causing it to expand. Why does this happen?
I am seeking an explanation for this behavior regarding block elements. While I acknowledge that this is fundamental, it is important to understand such intricacies.
If anyone could provide insights on this matter or direct me to resources explaining such nuances, it would be greatly appreciated. There are numerous subtle behaviors like this one that are often overlooked in tutorials. If you have discovered similar details while working on web development projects, feel free to share them in the comments or answers. Such information can be invaluable for those new to the field.