There are three common methods to achieve vertical centering: 1. Use Flexbox to achieve centering by setting the display: flex, align-items and justify-content attributes of the container, which is suitable for most block-level layouts; 2. Use Grid layout to achieve two-dimensional centering through the display: grid and place-items attributes, which is suitable for complex layout scenarios; 3. Use absolute positioning transform to achieve independent element centering by positioning the center point of the element and reverse offset, which does not depend on the container type. When choosing, trade-offs should be made based on project requirements and browser compatibility, and avoid using mobile devices that support poor table-cell methods.

Vertical centering looks simple in web page layout, but it often makes people feel troublesome in actual operation. Especially when different devices and contents are changing dynamically, it is not easy to make the elements truly "steadily" vertically centered. There are many common practices, such as using Flexbox, Grid, or some traditional techniques. The key is to understand the scenarios and limitations that each approach applies.

Use Flexbox to achieve vertical centering

Flexbox is the most commonly used and convenient way at present. Just set display: flex on the container, then add align-items: center and justify-content: center to easily achieve vertical and horizontal centering of child elements.

This method is suitable for centering elements in most block-level containers, such as putting text or icons in a div. But it should be noted that it requires that the parent container has a clear height, otherwise it may not take effect.

For example:

 .container {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100px;
}

If you find that an element is not centered, you can check whether its parent has set a height and whether other styles interfere with the behavior of flex.

Use Grid layout to achieve vertical centering

CSS Grid provides a Flexbox-like approach but more 2D layout. Likewise, it can also be very convenient to achieve vertical centering. Just set display: grid and place-items: center to achieve horizontal and vertical centering at the same time.

This approach is especially suitable for complex layouts that require control of rows and columns, such as card lists or dashboard interfaces.

 .container {
  display: grid;
  place-items: center;
  height: 200px;
}

However, it should be noted that Grid is not as compatible with Flexbox in some old browsers. If the project needs to support IE browsers, other solutions may be considered.

Center a single element with absolute positioning

For situations where only a single element is wanted to center, traditional absolute positioning can be used with transform attribute. This method does not require dependence on Flex or Grid, and is suitable for special scenarios such as pop-up windows or floating buttons.

The specific method is to set position: absolute for the element, then move the upper left corner to the center point through top: 50% and left: 50% , and then use transform: translate(-50%, -50%) to pull itself back half of the width and height, so as to achieve true centering.

 .centered {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

The advantage of this method is that it does not depend on the display type of the parent container. It can work normally as long as the parent has a positioning context (such as position: relative ).

Suggestions for choosing between different methods

• If you are doing responsive pages, give Flexbox priority, which is very compatible in modern browsers.
• If you are doing complex two-dimensional layouts, you can use Grid .
• If you just want to center an element and don't want to change the overall layout structure, then use absolute positioning transform .
• Avoid using table-cell, although it can also be centered vertically, the support on the mobile side is not friendly enough and prone to problems.

Basically these methods. Each type has its own advantages and limitations, the key is to flexibly choose according to the actual scenario.

The above is the detailed content of Solving vertical alignment challenges with CSS methods. For more information, please follow other related articles on the PHP Chinese website!