How Can I Effectively Override CSS Text Decoration Inheritance?

Understanding CSS Text Decoration Inheritance

In CSS, overriding text decoration can be a challenge. When a parent element with a text-decoration style is applied, it inherits its decoration to all its child elements. This can cause confusion when trying to control the decoration of specific elements.

The Case of Overriding Text Decoration

Consider the example provided, where the following CSS is used:

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 the HTML is as follows:

• Should not be underlined
• Should be underlined
  • Should not be underlined
  • Should be underlined

Here, the expected behavior is that the nested list items would receive no decoration, while the parent items with the u class would be underlined. However, the result shows that all list items are underlined.

The Explanation

The reason for this behavior lies in the nature of CSS text decoration. Unlike other font properties, text-decoration applies to the entire element, including all nested elements. This means that the decoration defined in the parent container applies recursively to its children, regardless of their own text-decoration styles.

This behavior is documented in the CSS21 specification:

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.

Conclusion

Overriding text decoration in CSS requires understanding this inheritance behavior. To ensure that specific elements do not inherit the decoration from their parent, it is necessary to define text-decoration: none for each level of the nesting.

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