CSS Margin Collapse

Sometimes two margins collapse into a single margin.

Margin Collapse

Top and bottom margins of elements are sometimes collapsed into a single margin that is equal to the largest of the two margins.

This does not happen on left and right margins! Only top and bottom margins!

Look at the following example:


Demonstration of margin collapse:

h1 {
  margin: 0 0 50px 0;

h2 {
  margin: 20px 0 0 0;

In the example above, the <h1> element has a bottom margin of 50px and the <h2> element has a top margin set to 20px.

Common sense would seem to suggest that the vertical margin between the <h1> and the <h2> would be a total of 70px (50px + 20px). But due to margin collapse, the actual margin ends up being 50px.

All CSS Margin Properties

Property Description
margin A shorthand property for setting the margin properties in one declaration
margin-bottom Sets the bottom margin of an element
margin-left Sets the left margin of an element
margin-right Sets the right margin of an element
margin-top Sets the top margin of an element


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