Designated by a colon preceding the name, pseudo-classes are independent of particular elements and instead look at what's happening within the document.
伪类的表示方法是在名称前面加一个冒号。伪类与特定元素无关，而是根据文档中发生的情况应用样式。
A simple selector is either a type selector or universal selector followed immediately by zero or more attribute selectors, ID selectors, or pseudo-classes, in any order.
一个简单选择符或者是一个类型选择符，或者是一个全局选择符，紧跟在后的是零个或多个属性选择符，ID选择符或伪类，次序任意。
A simple selector is either a type selector or universal selector followed immediately by zero or more attribute selectors, ID selectors, or pseudo-classes, in any order.
一个简单选择符或者是一个类型选择符，或者是一个全局选择符，紧跟在后的是零个或多个属性选择符，ID选择符或伪类，次序任意。
应用推荐