Why Aren't My Absolutely or Fixed-Positioned Elements Where I Expect Them?-CSS Tutorial-php.cn

Why Aren't My Absolutely or Fixed-Positioned Elements Where I Expect Them?

Mary-Kate Olsen

Release： 2024-12-30 09:03:14

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Why Aren't My Absolutely or Fixed-Positioned Elements Where I Expect Them?

Why Absolutely or Fixed-Positioned Elements Are Not Located Where Expected

In CSS positioning, absolutely and fixed elements are placed relative to the viewport or the nearest positioned parent element, respectively. However, understanding their behavior can sometimes be challenging.

Understanding the Static Position

When an element's position property is set to auto or static, it assumes the static position. This means it will be placed as if its position were static. In this case, the element's position is calculated based on its margins, borders, padding, and content.

Scenario 1: Absolute Gray Box Outside the Relative Parent

In your first code snippet, the gray box has an absolute position. However, the parent container (

) has a position: relative; property, which creates a new positioning context for its children. Because the gray box is the last child, it will be positioned relative to the bottom of the container.

Scenario 2: Gray Box Not in the Top-Left Corner

In your second code snippet, you have moved the gray box to the second position within the container. However, it is still not in the top-left corner because the container has a padding: 40px 20px; rule, which affects the hypothetical static position of the element. The gray box will be positioned relative to this adjusted static position.

Conclusion

To correctly position absolute or fixed elements, it is crucial to understand the concept of the static position and how it is calculated based on margins, borders, padding, and content. This knowledge enables you to anticipate the behavior of these elements within different positioning contexts.

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