What are the characteristics of fixed positioning?

Fixed positioning has the characteristics of positioning relative to the viewport, not occupying the document flow, not affected by scrolling, resident in the viewport, fixed position and good compatibility. Detailed introduction: 1. Positioning relative to the viewport. Fixed positioning is positioned relative to the viewport, not relative to other elements in the document flow. This means that no matter how the page scrolls, the fixed positioning element will remain in view. 2. It does not occupy the document flow. Fixed-positioned elements are separated from the document flow and will not affect the layout of other elements. Other elements will ignore fixed-positioned elements, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

Fixed Positioning (Fixed Positioning) is a CSS positioning method that allows elements to be fixed at a specific position on the page relative to the viewport and not change position as the page scrolls. Fixed positioning has the following characteristics:

1. Positioning relative to the viewport: Fixed positioning is positioned relative to the viewport, not relative to other elements in the document flow. This means that fixedly positioned elements will remain at the specified position in the viewport no matter how the page is scrolled.

2. Does not occupy the document flow: fixedly positioned elements are separated from the document flow and will not affect the layout of other elements. Other elements ignore the fixedly positioned element and act as if it does not exist. Therefore, fixedly positioned elements do not affect the position and layout of other elements.

3. Not affected by scrolling: fixedly positioned elements will not change position as the page scrolls. Fixed-positioned elements remain at the specified position in the viewport no matter how the user scrolls the page. This makes fixedly positioned elements very useful for creating fixed navigation bars, floating tooltips, back to top buttons, etc.

4. Permanent viewport: Fixedly positioned elements are always visible, no matter how the user scrolls the page. This makes fixedly positioned elements very useful where important information, advertising or navigation needs to be displayed at all times. Users can access these elements at any time without scrolling the page.

5. Fixed position: The position of fixedly positioned elements is relative to the viewport. You can specify the position of the element relative to the viewport by setting top, bottom, left, right and other attributes. This way, you can precisely control the position of a fixed positioning element so that it appears where you expect it to.

6. Good compatibility: Fixed positioning is widely supported in modern browsers, including Chrome, Firefox, Safari and Edge. For browsers that do not support fixed positioning, elements are displayed according to normal document flow.

The method of using fixed positioning is very simple. You only need to set the position attribute of the element to fixed. At the same time, you also need to specify the position of the element in the viewport. You can use attributes such as top, bottom, left, and right to specify the offset value of the element relative to the viewport.

Here is an example:

.fixed-element {
  position: fixed;
  top: 20px; /* 元素相对于视口顶部的偏移值 */
  left: 20px; /* 元素相对于视口左侧的偏移值 */
}

In the above example, elements of the .fixed-element class will be set to fixed positioning and offset by 20 relative to the top and left of the viewport The position of the pixel.

In summary, fixed positioning is a very practical CSS positioning method. It can fix elements at a specific position on the page and is not affected by page scrolling. Fixed-positioned elements are positioned relative to the viewport, do not occupy the document flow, are resident in the viewport, have a fixed position, and have good compatibility. By rationally using fixed positioning, you can achieve various attractive effects and improve user experience and page interactivity.

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