码农教程 - 一技在手,衣食无忧! tools

目录

CSS Layout - Horizontal & Vertical Align

❮ Previous Next ❯

▲ ▼
◀ ►

Center elements
horizontally and vertically

Center Align Elements

To horizontally center a block element (like <div>), use margin: auto;

Setting the width of the element will prevent it from stretching out to the edges of its container.

The element will then take up the specified width, and the remaining space will be split equally between the two margins:

This div element is centered.

Example

.center {
  margin: auto;
  width: 50%;
  border: 3px solid green;
  padding: 10px;
}
Try it Yourself »

Note: Center aligning has no effect if the width property is not set (or set to 100%).

Center Align Text

To just center the text inside an element, use text-align: center;

This text is centered.

Example

.center {
  text-align: center;
  border: 3px solid green;
}
Try it Yourself »

Tip: For more examples on how to align text, see the CSS Text chapter.

Center an Image

To center an image, set left and right margin to auto and make it into a block element:

Paris

Example

img {
  display: block;
  margin-left: auto;
  margin-right: auto;
  width: 40%;
}
Try it Yourself »

Left and Right Align - Using position

One method for aligning elements is to use position: absolute;:

In my younger and more vulnerable years my father gave me some advice that I've been turning over in my mind ever since.

Example

.right {
  position: absolute;
  right: 0px;
  width: 300px;
  border: 3px solid #73AD21;
  padding: 10px;
}
Try it Yourself »

Note: Absolute positioned elements are removed from the normal flow, and can overlap elements.

Left and Right Align - Using float

Another method for aligning elements is to use the float property:

Example

.right {
  float: right;
  width: 300px;
  border: 3px solid #73AD21;
  padding: 10px;
}
Try it Yourself »

The clearfix Hack

Note: If an element is taller than the element containing it, and it is floated, it will overflow outside of its container. You can use the "clearfix hack" to fix this (see example below).

Without Clearfix

With Clearfix

Then we can add the clearfix hack to the containing element to fix this problem:

Example

.clearfix::after {
  content: "";
  clear: both;
  display: table;
}
Try it Yourself »

Center Vertically - Using padding

There are many ways to center an element vertically in CSS. A simple solution is to use top and bottom padding:

I am vertically centered.

Example

.center {
  padding: 70px 0;
  border: 3px solid green;
}
Try it Yourself »

To center both vertically and horizontally, use padding and text-align: center:

I am vertically and horizontally centered.

Example

.center {
  padding: 70px 0;
  border: 3px solid green;
  text-align: center;
}
Try it Yourself »

Center Vertically - Using line-height

Another trick is to use the line-height property with a value that is equal to the height property:

I am vertically and horizontally centered.

Example

.center {
  line-height: 200px;
  height: 200px;
  border: 3px solid green;
  text-align: center;
}

/* If the text has multiple lines, add the following: */
.center p {
  line-height: 1.5;
  display: inline-block;
  vertical-align: middle;
}
Try it Yourself »

Center Vertically - Using position & transform

If padding and line-height are not options, another solution is to use positioning and the transform property:

I am vertically and horizontally centered.

Example

.center {
  height: 200px;
  position: relative;
  border: 3px solid green;
}

.center p {
  margin: 0;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
Try it Yourself »

Tip: You will learn more about the transform property in our 2D Transforms Chapter.

Center Vertically - Using Flexbox

You can also use flexbox to center things. Just note that flexbox is not supported in IE10 and earlier versions:

I am vertically and horizontally centered.

Example

.center {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 200px;
  border: 3px solid green;
}
Try it Yourself »

Tip: You will learn more about Flexbox in our CSS Flexbox Chapter.

Test Yourself With Exercises

Exercise:

Use the margin property to make sure that the <div> element is center aligned according to its parent element.

<style>
.intro {
  width: 200px;
  : ;
}
</style>

<body>

<div class="intro">
Lorem ipsum dolor sit amet,
consectetur adipiscing elit.
Phasellus imperdiet, nulla et dictum interdum,
nisi lorem egestas odio,
vitae scelerisque enim ligula venenatis dolor.
</div>

</body>

Start the Exercise


❮ Previous Next ❯