根据您的链接：
unset是一个CSS值，如果继承了一个属性，则该属性与“继承”相同；如果不继承一个属性，则其属性为“初始”
这是一个例子：
pre { color: #f00;}.initial { color: initial;}.unset { color: unset;}<pre> <span>This text is red because it is inherited.</span> <span >[color: initial]: This text is the initial color (black, the browser default).</span> <span >[color: unset]: This text is red because it is unset (which means that it is the same as inherited).</span></pre>如果您要覆盖样式表中的某些CSS，但您更希望该值是继承的，而不是设置回浏览器的默认值，那么这种情况就很重要。
例如：
pre { color: #00f;}span { color: #f00;}.unset { color: unset;}.initial { color: initial;}<pre> <em>Text in this 'pre' element is blue.</em> <span>The span elements are red, but we want to override this.</span> <span >[color: unset]: This span's color is unset (blue, because it is inherited from the pre).</span> <span >[color: initial]: This span's color is initial (black, the browser default).</span></pre>
