Introduction to two practical attributes of CSS3

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First, use: not () to apply / unapply borders on the menu

Our usual practice is to set a border for each menu item, and then set the border of the last menu to zero

/ * add border * / .nav li {border-right: 1px solid # 666;} / * remove border * / .nav li:last-child {border-right: none;} web front-end development Learning Q-q-u-n: 731771211, share learning methods and small details that need to be paid attention to, and constantly update the latest tutorials and learning methods (detailed front-end project practical teaching video, PDF)

But don't do this, use the: not () pseudo class to achieve the same effect:

.nav li:not (: last-child) {border-right: 1px solid # 666;}

Of course, you can also use .nav li + li or .nav li:first-child ~ li, but not () is clearer and readable

.nav li + li {border-left:1px solid # 666;} / * .nav li:first-child ~ li {border-left:1px solid # fff;} * / II. Use: nth-child (n) to select a project

(note: the subscript of the first child element is 1)

: nth-child (3) indicates the third element in the selection list

: nth-child (2n) represents an even number of tags in the list, that is, select 2nd, 4th, 6th. Label

: nth-child (2n-1) represents the odd tag in the selection list, that is, select 1st, 3rd, 5th, 7th... Label

: nth-child (nasty 3) indicates that the label in the selection list starts from the 3rd to the end (> = 3)

: nth-child (- naugh3) indicates that the tags in the selection list range from 0 to 3, that is, tags less than 3 (