Συγχώνευση Περιθωρίων CSS
- Προηγούμενη Σελίδα Περιθώρια CSS
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Margin collapsing refers to the formation of a margin when two vertical margins meet.
The height of the merged margin is equal to the larger of the two margins that collapse.
Margin collapsing
Margin collapsing (stacking) is a relatively simple concept. However, in practice, it can cause much confusion when laying out web pages.
In simple terms, margin collapsing refers to the formation of a margin when two vertical margins meet. The height of the merged margin is equal to the larger of the two margins that collapse.
When an element appears above another element, the bottom margin of the first element and the top margin of the second element will collapse. See the following figure:

When an element is contained within another element (assuming there are no padding or borders to separate the margins), their top and/or bottom margins will also collapse. See the following figure:

Although it may seem strange, margins can even collapse with themselves.
Suppose there is an empty element with a margin but no border or padding. In this case, the top margin and the bottom margin meet each other, and they will collapse:

If this margin encounters the margin of another element, it will also collapse:

This is why a series of paragraph elements occupy very little space, because all their margins are merged into a small margin.
Margin collapsing may seem strange at first glance, but in fact, it is meaningful. Take a typical text page composed of several paragraphs as an example. The space above the first paragraph is equal to the top margin of the paragraph. If there is no margin collapsing, the margins between all subsequent paragraphs will be the sum of the adjacent top and bottom margins. This means that the space between paragraphs is twice the space at the top of the page. If margin collapsing occurs, the top and bottom margins between paragraphs will merge together, making the distances consistent.

Note:Only the vertical margins of block boxes in the normal document flow will cause margin collapsing. The margins between inline boxes, floating boxes, or absolutely positioned boxes will not collapse.
All CSS margin properties
Ιδιότητα | Περιγραφή |
---|---|
margin | Απλοποιημένη ιδιότητα για τη ρύθμιση των εξωτερικών περιθωρίων σε μια γραμμή δήλωσης. |
margin-bottom | Ρύθμιση της κάτω εξωτερικής κύριας γωνίας του στοιχείου. |
margin-left | Ρύθμιση της αριστεράς εξωτερικής κύριας γωνίας του στοιχείου. |
margin-right | Ρύθμιση της δεξιάς εξωτερικής κύριας γωνίας του στοιχείου. |
margin-top | Ρύθμιση της επάνω εξωτερικής κύριας γωνίας του στοιχείου. |
- Προηγούμενη Σελίδα Περιθώρια CSS
- Επόμενη Σελίδα Περιθώρια Εσωτερικά CSS