初始值和未设置值有什么区别？

Question

一个简单的例子：

HTML

<p style="color:red!important"> 
    this text is red 
    <em> 
       this text is in the initial color (e.g. black)
    </em>
    this is red again
</p>

CSS

em {
    color:initial;
    color:unset;
}

initial和之间有什么区别unset？仅支持浏览器

Answer 1

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 class="initial">[color: initial]: This text is the initial color (black, the browser default).</span>

  <span class="unset">[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 class="unset">[color: unset]: This span's color is unset (blue, because it is inherited from the pre).</span>

  <span class="initial">[color: initial]: This span's color is initial (black, the browser default).</span>

</pre>