如何防止 CSS 继承？

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just set them back to their defaults in the "#sidebar ul li" selector

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You either use the child selector

So using

#parent > child

Will make only the first level children to have the styles applied. Unfortunately IE6 doesn't support the child selector.

Otherwise you can use

#parent child child

To set another specific styles to children that are more than one level below.

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最佳答案

As of yet there are no parent selectors (or as Shaun Inman calls them, qualified selectors), so you will have to apply styles to the child list items to override the styles on the parent list items.

Cascading is sort of the whole point of Cascading Style Sheets, hence the name.

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You could use something like jQuery to "disable" this behaviour, though I hardly think it's a good solution as you get display logic in css & javascript. Still, depending upon your requirements you might find jQuery's css utils make life easier for you than trying hacky css, especially if you're trying to make it work for IE6

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There is a property called all in the CSS3 inheritance module. It works like this:

#sidebar ul li {
all: initial;
}

As of 2016-12, all browsers but IE/Edge and Opera Mini support this property.

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For example if you have two div in XHTML document.

<div id='div1'>
<p>hello, how are you?</p>
<div id='div2'>
<p>I am fine, thank you.</p>
</div>
</div>

Then try this in CSS.

#div1 > #div2 > p{
color: red;
}

affect only 'div2' paragraph.

#div1 > p {
color: red;
}

affect only 'div1' paragraph.

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You can use the * selector to change the child styles back to the default

example

#parent {
white-space: pre-wrap;
}


#parent * {
white-space: initial;
}

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Wrapping with iframe makes parent css obsolete.

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You don't need the class reference for the lis. Instead of having CSS like

li.top-level-nav { color:black; }

you can write

ul#sidebar > li { color:black; }

This will apply the styling only to lis that immediately descend from the sidebar ul.

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Short answer is: No, it's not possible to prevent CSS inheritance. You can only override the styles that are set on the parents. See the spec:

Every element in an HTML document will inherit all inheritable properties from its parent except the root element (html), which doesn’t have a parent. -W3C

Apart from overriding every single inherited property. You can also use initial keyword, e.g. color: initial;. It also can be used together with all, e.g. all: initial;, that will reset all properties at once. Example:

.container {
color: blue;
font-style: italic;
}
.initial {
all: initial;
}

<div class="container">
The quick brown <span class="initial">fox</span> jumps over the lazy dog
</div>

Browser support tables according to Can I use...

all (Currently no support in both IE and Edge, others are good)
initial (Currently no support in IE, others are good)

You may find it useful by using direct children selector > in some cases. Example:

.list > li {
border: 1px solid red;
color: blue;
}

<ul class="list">
<li>
<span>HEADING 1</span>
<ul>
<li>sub-heading A</li>
<li>sub-heading B</li>
</ul>
</li>
<li>
<span>HEADING 2</span>
<ul>
<li>sub-heading A</li>
<li>sub-heading B</li>
</ul>
</li>
</ul>

The border style has been applied only to the direct children <li>s, as border is an non-inherited property. But text color has been applied to all the children, as color is an inherited property.

Therefore, > selector would be only useful with non-inherited properties, when it comes to preventing inheritance.

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You may use Shadow Dom which is a new feature provided by browsers. Browser support is also pretty decent for the date.

Documentation: https://developer.mozilla.org/en-US/docs/Web/Web_Components/Using_shadow_DOM

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You can wrap the element that you don't want to inherit any styles in a div with no style.

Something like this:

<div style='all: revert !important;'>
Your content here
</div>

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here's an live example using cascade, initial and all property:

div {
border: 1px solid red;
margin: 10px;
}


div p {
color: red;
}


.initial {
border-color: initial;
}


.initial p {
color: initial;
}


.asterisk,
.asterisk * {
border-color: initial;
color: initial;
}


.all,
.all * {
all: initial
}

https://jsbin.com/cosabusiwi/1/edit?html,css,output