When using * general-purpose selector, its scope of action and performance impact should be clarified. It is often used to reset the default style (such as clear margins, fill), debug layouts, or unify global styles (such as fonts, transitions), but abuse can lead to style conflicts or performance degradation. Since it matches all elements, adding complex properties (such as box-shadow) will slow down rendering, especially in large projects. Additionally, there may be compatibility issues in dynamically loading content or in older browsers. To improve accuracy, it can be used in combination with pseudo-classes or attribute selectors, such as excluding specific classes or restricting child element style inheritance. The key to using * well is "less is more", and prioritizes more specific selectors to avoid unnecessary coverage.

When using * general-purpose selector, it is key to understand its scope of action and performance impact. It matches all elements in the document, and while flexible, abuse can lead to style conflicts or page performance degradation.

Clarify usage scenarios

* Usually used in the following situations:

• Reset the default style : such as clearing margins and padding of all elements.

   * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }

• Debugging purpose : Temporarily highlight all elements and view the layout structure.

  

• Global style control : such as unified font setting, transition effects, etc.

But in most cases, more specific selectors should be preferred to avoid unnecessary style overwrites on all elements.

Pay attention to performance and compatibility

Although modern browsers are already very efficient in handling * , it still performs style calculations on every element in the page. If you add complex style rules inside, it may affect rendering speed, especially in large projects.

Some things to note:

• Avoid using expensive properties such as box-shadow or filter in * .
• Do not rely on * to apply styles on pages where content is loaded dynamically, as new elements may be inconsistent in styles.
• In older browsers (such as IE), some styles may not be applied as expected.

Use more accurately with other selectors

Sometimes you don't really need to select "all elements", but instead want to exclude certain elements, or apply styles only for some nested structures. At this time, you can combine pseudo-classes or attribute selectors to enhance control:

 *:not(.ignore) {
  color: red;
}

It can also be used as style isolation for child elements:

 .container * {
  color: blue;
}

In this way, all child elements under .container will inherit blue text without affecting external elements.

Basically that's it. The key to using * is "less is more" - only use it when it really needs to affect all elements, otherwise try to maintain the accuracy of the selector.

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