css - 什么 margin :5px 0; and margin:5px 0 0; mean?

Question

margin:5px 0; 是 margin:5px 0 0 0; 还是 margin:5px 0 5px 0;？

margin:5px 0 0; 是 margin:5px 0 0 0; 的意思吗？

填充当然也一样。

此外，它在所有浏览器(包括 IE6)中是否一致？

Answer 1

根据 Box Model :

• If there is only one value, it applies to all sides.
• If there are two values, the top and bottom margins are set to the first value and the right and left margins are set to the second.
• If there are three values, the top is set to the first value, the left and right are set to the second, and the bottom is set to the third.
• If there are four values, they apply to the top, right, bottom, and left, respectively.

body { margin: 2em }         /* all margins set to 2em */
body { margin: 1em 2em }     /* top & bottom = 1em, right & left = 2em */
body { margin: 1em 2em 3em } /* top=1em, right=2em, bottom=3em, left=2em */

这是由 CSS 标准定义的，因此它应该在所有正确实现 CSS 的浏览器中保持一致。对于浏览器兼容性，请查看 blooberry 的 CSS Support History和 quirksmode .根据 blooberry 的说法，margin 最早是在 IE3 中实现的，所以 IE6 应该没问题。