Defines the space outside the element, on the top side.

默认属性 margin-top: 0;

Removes any margin at the top.

margin-top: 30px;

You can use pixel values.

margin-top: 2em;

You can use (r)em values.

The value is relative to the font size:

  • em: relative to the element's current font size
  • rem: relative to <html> the root element's font size

margin-top: 10%;

You can use percentage values.
The percentage is based on the width of the container.