What positioning is based on fixed positioning?

Fixed positioning is based on the browser window, not the parent element or other elements. When an element's position attribute is set to fixed, the element is removed from the document flow and its position is determined by the top, right, bottom, and left attributes. When using pixel values, the element is positioned relative to the upper left corner of the browser window. You can adjust the element's position by setting the value of these properties. If you use a percentage value, the position of the element is dynamically adjusted based on the size of the browser window.

Fixed positioning is a value of the positioning attribute (position) in CSS, which can position the element at a specific position in the browser window, even if the page is scrolled. The element will also always stay in the same position. This positioning method is based on the browser window, not on the parent element or other elements.

Specifically, when the position attribute of an element is set to fixed, the element will be separated from the document flow, and its position is determined by the top, right, bottom, and left attributes. The values ​​of these properties can be pixel values, percentages, or auto. When using pixel values, the element is positioned relative to the upper left corner of the browser window. You can adjust the element's position by setting the value of these properties. If you use a percentage value, the position of the element is dynamically adjusted based on the size of the browser window.

Fixed positioning is often used for elements that need to always be displayed on the page, such as navigation bars, return to top buttons, etc. No matter which part of the page the user scrolls, these elements stay in the same place for ease of use. In some complex page layouts, fixed positioning can also be used to achieve some special effects, such as fixed background images, sidebars, etc.

It should be noted that fixed positioning elements will break away from the document flow, which may cause some layout problems. For example, if a fixed positioning element blocks other elements, it may affect the user's interactive experience. In addition, fixed positioning elements may also block important content on the page, so attention should be paid to their rationality and accessibility when used.

There is also a relative positioning method, which is also one of the commonly used positioning methods in CSS. Relative positioning is relative to the position of the element in the normal document flow. By setting attributes such as left and top, the element can be offset relative to its original position. This positioning method does not break away from the document flow, and the elements are arranged according to their offset position.

Relative positioning is often used when the position of an element needs to be adjusted. For example, when making a form, you can set the label element to relative positioning, and offset the label element relative to its original position by setting the left and top attributes. , to facilitate users to view and fill in the form content.

It should be noted that the position of relatively positioned elements will be affected by other elements. If the positions of surrounding elements change, the relative position of relatively positioned elements will also change accordingly. Therefore, when using relative positioning, you need to consider the surrounding layout environment to ensure that it does not negatively affect the layout and use of the page.

In short, there are many positioning methods in CSS, and you can choose the appropriate positioning method according to specific needs and scenarios. Fixed positioning is often used for elements that need to always be displayed on the page, while relative positioning is often used when the position of the element needs to be adjusted. When using these positioning methods, you need to pay attention to the rationality and accessibility of their use to ensure that the layout and use of the page are not affected.

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