To center a div horizontally and vertically, 1. Use Flexbox: the parent container to set display: flex, justify-content and align-items as center; 2. Use Grid: the parent container to set display: grid, place-items as center; 3. Add transform to absolute positioning: set child elements to absolute, top and left to 50%, and then translate -50%. It should be noted that margin: 0 auto can only achieve horizontal centering.
Wanting a div
to center horizontally and vertically in the page is a common requirement in front-end layout. There are several ways to implement it, but the applicable methods in different scenarios are slightly different. Here are several practical and easy-to-understand ways.
Quickly implement with Flexbox
Flexbox is one of the most commonly used and convenient tools in modern web layouts. You only need to set a few properties on the parent container to easily achieve centering.
.parent { display: flex; justify-content: center; /* horizontal center*/ align-items: center; /* vertical center*/ }
In this way, the child elements in .parent
(such as your div
) will be automatically centered.
This method works for most modern browsers and is also very compatibility. If your project does not need to support too old browser versions, this should be the preferred option.
Tip: If you only want to center a specific
div
, you can temporarily set its parent toflex
without global changes.
Using Grid layout is also easy
CSS Grid also provides a simple way to achieve centering effect, suitable for situations where you are already using Grid.
.parent { display: grid; place-items: center; }
This code is equivalent to setting both vertical and horizontal centering.
Grid is written more concise than Flex, but if you just do a simple centering, there may be no need to switch the entire layout system for this function.
- Advantages : The grammar is more intuitive.
- Disadvantages : It is a bit "small" for doing small things like centering.
Classic method: Absolute positioning transform
If your div
is an absolute positioning element that is separated from the document stream, or the parent container cannot set flex
or grid
, you can use the following method:
.child { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); }
This method is suitable for pop-up windows, floating layers and other scenarios.
It does not rely on the display mode of the parent container, so it is more flexible, but it also means you need to manually handle the positioning context, such as making sure the parent is position: relative
.
Don't forget margin: 0 auto can only be centered horizontally
A common mistake for beginners is thinking that margin: 0 auto
can be vertically centered. In fact, it can only control the horizontal centering, and it needs to be matched with the width to take effect.
.child { width: 200px; margin: 0 auto; }
If you just want the block-level element to be centered horizontally, then that's fine; but if you want to center vertically at the same time, you have to change to another method.
Basically these common practices. Just choose the most suitable one according to the specific situation. Flex and Grid are the most convenient, and the traditional positioning method is more flexible, depending on how you use it.
The above is the detailed content of How to center a div vertically and horizontally with CSS. For more information, please follow other related articles on the PHP Chinese website!

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