after pseudo element not appearing in code [duplicate]

问题

I'm trying to use the after pseudo element to add some effects to a site.

<div class="product-show style-show">
  <ul>
    <li>
      ....
      <div class="...">
        <div class="readMore less">...</div>
        <a href="3" class="readMoreLink" onclick="return false;">Read More</a>
      </div>
      ....
    </li>
  </ul>
</div>

And stylesheets:

.product-show .readMore.less {
   max-height: 200px;
   height: 100%;
   overflow: hidden;
}

.product-show .readMore.less:after {
   background: rgba(255, 255, 255, 0);
   display: block;
   position: absolute;
   bottom: 0;
   left: 0;
   width: 100%;
   height: 30px;
 }

I see the styling for .product-show .readMore.less being applied, but I don't see a ::after notation in the HTML blocks when I'm examining the site from Chrome (latest version)/MacOS. I read that there are sometimes issues with older browsers, but I assumed that I should be able to see at least the ::after pseudo element notation if I was defining the style correctly. What am I doing wrong?

回答1:

It's because the pseudo-element isn't generated if the content value is omitted (since the initial/default value is none).

Specify a content value in order to generate the pseudo-element. A value of '' is sufficient.

.product-show .readMore.less:after {
    content: '';
    background: rgba(255, 255, 255, 0);
    display: block;
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 30px;
}

回答2:

As per the MDN:

The content CSS property is used with the ::before and ::after pseudo-elements to generate content in an element.

What this means is that if you don't include the content property, the :after or :before element won't show altogether.

Add this line into your code:

content: ""; // Leave this empty

And see how that affects the result.

Just as a note, you would normally add text into the content property when the :before or :after element is used to display text. In many cases though, you would find that you are simply leaving it empty.

来源：https://stackoverflow.com/questions/29572730/after-pseudo-element-not-appearing-in-code

标签

html

css

pseudo-element

css-content