How do I get this CSS text-decoration override to work?

问题

Some days I swear I\'m going mad. This is one of those days. I thought my CSS was fairly straight-forward here, but it just doesn\'t seem to be working. What am I missing?

My CSS looks like this:

ul > li {
    text-decoration: none;
}
ul > li.u {
    text-decoration: underline;
}
ul > li > ul > li {
    text-decoration: none;
}
ul > li > ul > li.u {
    text-decoration: underline;
}

And my HTML looks like this:

<ul>
  <li>Should not be underlined</li>
  <li class=\"u\">Should be underlined
    <ul>
      <li>Should not be underlined</li>
      <li class=\"u\">Should be underlined</li>
    </ul>
  </li>
</ul>

Yet it comes up like this:

$\"Image\"$

回答1:

text-decoration does not behave the same as other font/text related styling like font-weight. Applying text-decoration will affect all nested elements as well.

Check this out: http://www.w3.org/TR/CSS21/text.html#propdef-text-decoration

Excerpt:

Text decorations on inline boxes are drawn across the entire element, going across any descendant elements without paying any attention to their presence. The 'text-decoration' property on descendant elements cannot have any effect on the decoration of the element
. . . .
Some user agents have implemented text-decoration by propagating the decoration to the descendant elements as opposed to simply drawing the decoration through the elements as described above. This was arguably allowed by the looser wording in CSS2.

I've got the info from: http://csscreator.com/node/14951

回答2:

You get rid of text-decoration applied to a parent element in those cases:

Out-of-flow elements, such as floated and absolutely positioned ones

li {
  float: left; /* Avoid text-decoration propagation from ul */
  clear: both; /* One li per line */
}
ul { overflow: hidden; } /* Clearfix */

ul {
  overflow: hidden; /* Clearfix */
}
li {
  float: left; /* Avoid text-decoration propagation from ul */
  clear: both; /* One li per line */
}
li.u {
  text-decoration: underline;
}

<ul>
  <li>Should not be underlined</li>
  <li class="u">Should be underlined
    <ul>
      <li>Should not be underlined</li>
      <li class="u">Should be underlined</li>
    </ul>
  </li>
</ul>

Atomic inline-level elements, such as inline blocks and inline tables

But if you use li{display:inline-block}, then you don't have bullets (you lose display:list-item) and the items appear one next to the others.

Then, to have one item per line, you can use

li {
  display: inline-block; /* Avoid text-decoration propagation from ul */
  width: 100%;           /* One li per line */
}

And to add the bullets, you can use ::before pseudo-elements. However, bullets shouldn't be underlined, so you will need to take them out-of-flow or make them atomic inline-level too.

li {
  display: inline-block; /* Avoid text-decoration propagation from ul */
  width: 100%;           /* One li per line */
}
li:before {
  content: '• ';         /* Insert bullet */
  display: inline-block; /* Avoid text-decoration propagation from li */
  white-space: pre-wrap; /* Don't collapse the whitespace */
}
li.u {
  text-decoration: underline;
}

<ul>
  <li>Should not be underlined</li>
  <li class="u">Should be underlined
    <ul>
      <li>Should not be underlined</li>
      <li class="u">Should be underlined</li>
    </ul>
  </li>
</ul>

li {
  display: inline-block; /* Avoid text-decoration propagation from ul */
  width: 100%;           /* One li per line */
}
li:before {
  content: '•';          /* Insert bullet */
  position: absolute;    /* Avoid text-decoration propagation from li */
  margin-left: -.75em;
}
li.u {
  text-decoration: underline;
}

<ul>
  <li>Should not be underlined</li>
  <li class="u">Should be underlined
    <ul>
      <li>Should not be underlined</li>
      <li class="u">Should be underlined</li>
    </ul>
  </li>
</ul>

This behavior is specified in CSS 2.1 and CSS Text Decoration Module Level 3:

Note that text decorations are not propagated to any out-of-flow descendants, nor to the contents of atomic inline-level descendants such as inline blocks and inline tables.

回答3:

o.k.w.'s answer above explains perfectly why you can't do what you are asking without some other changes. No, you're not going mad!

Possible workarounds:

try border-bottom?
wrap the text you want underlined in a span class="u" tag? (to prevent the text-decoration from decorating nested elements)
if you aren't able to change the markup, you could add some scripting to accomplish the same as my previous suggestion.

Best of luck!

回答4:

The reason you´re seeing what you're seeing is that your rule

ul > li.u

takes preference over:

ul > li > ul > li

as a class is specified and that has more weight than the element selectors together.

Edit: What you could try is:

.u ul {
        text-decoration: none;
}
.u {
        text-decoration: underline;
}

and play around with that (perhaps you will have to use li.u instead of just .u).

However, depending on the content you might want to wrap the underlined parts in q, em or strong tags and style these tags instead of using a class. That way you would be describing your content as well as styling it.

回答5:

.u {text-decoration: underline;}

来源：https://stackoverflow.com/questions/1823341/how-do-i-get-this-css-text-decoration-override-to-work

标签

html

css

text-decorations