How to use z-index

The z-index attribute is used to control the stacking order of HTML elements on the page. The larger the value, the higher the element is. Usage steps: Set the z-index attribute for the overlay element. Specify an integer as the attribute value. The larger the value, the higher the stacking order. Make sure the parent element has an explicit positioning attribute, z-index only applies to positioned elements.

How to use z-index

The z-index attribute is used to control the cascading of HTML elements on the page. order. Its value is an integer; the higher the number, the higher the element appears in the stacking order, above other elements.

Usage steps:

1. Set the z-index attribute for the element you want to overlay.
2. Specify an integer as the attribute value. The larger the value, the higher the stacking order of the elements.
3. Make sure the parent element has an explicit positioning attribute. z-index only applies to elements with positioning attributes such as position: absolute, position: fixed, or position: relative.

Example:

<div style="position: relative;">
  <div style="position: absolute; z-index: 2;">元素 1</div>
  <div style="position: absolute; z-index: 1;">元素 2</div>
</div>

In this example, the z-index of "Element 1" is 2, and the z-index of "Element 2" is 1. "Element 1" will appear above "Element 2" because its z-index value is higher.

Other notes:

• If two elements have the same z-index, the later-declared element will appear on top of the earlier-declared element .
• z-index only controls the stacking order of elements within the same parent element and will not affect the stacking order of other elements on the page.
• For fixed positioned elements, z-index is calculated relative to the viewport (browser window), not the parent element.

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