css to implement image adaptive width and height

With the development of the Internet, pictures have become an inevitable part of our daily lives. In website design, the use of pictures can make the website more beautiful and vivid. However, many times, we will encounter a problem: the aspect ratio of the image does not match the layout of the website, resulting in the image being displayed incompletely or stretched and deformed. In order to solve this problem, today we will discuss how to use CSS to achieve adaptive width and height of images.

1. Set the position attribute of the parent element

Before implementing the adaptive width and height of the image, we need to first understand a CSS attribute: position.

The position attribute defines the positioning method of the element, including the following four values:

static: the normal layout of the element, the left, right, top, bottom and z-index attributes are invalid.

relative: relative positioning, the element still retains its original position in the document flow, but can be offset relative to its normal (static) position by setting the top, bottom, left, and right attributes.

Absolute: Absolute positioning, the element is extracted from the document flow and positioned relative to its already positioned ancestor elements.

fixed: fixed positioning, the element is fixedly positioned relative to the browser window.

In the implementation of adaptive width and height of images, we need to use relative or absolute attributes. In order to facilitate the operation, we first set the position attribute of the parent element to relative. The code is as follows:

.parent { position: relative; }

2. Set the position and max-width attributes of the image

After setting the position attribute of the parent element After that, the next step is to set the CSS style of the image. First, we need to set the position attribute of the image to absolute so that it can be positioned in the parent element. At the same time, in order to ensure that the image does not exceed the width of the parent element, we need to use the max-width attribute to control the maximum width of the image and make the image adapt to the width of the parent element. The code is as follows:

.parent { position: relative; } .image { position: absolute; max-width: 100%; }

Through the above code, the width of the image will adapt along with the width of the parent element, while maintaining the original width-to-height ratio without being destroyed.

3. Set the top and left attributes of the image

In order to position the image in the parent element, we also need to set the top and left attributes of the image. Here, we can use the percentage value to set it to achieve adaptive width and height of the image. Normally, we set the position of the image to be centered. The code is as follows:

.parent { position: relative; } .image { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); max-width: 100%; }

By setting the top and left attributes, the image will be positioned based on the center point. Using the transform: translate(-50%, -50%); attribute can center the image without affecting the adaptive width and height of the image.

Summary:

By setting the position attribute of the parent element, the position, max-width, and top and left attributes of the image, we can easily implement the adaptive width and height of the image. For developers who need to use a large number of images in their websites, this method can greatly reduce the workload while improving the user experience of the website.

In practice, we also need to pay attention to the following points:

1. Ensure that the parent element is set correctly to avoid affecting the display of other elements.
2. Pay attention to the centering of the image, especially when using percentage values.
3. Try to use appropriate image sizes and formats to ensure page loading speed.

I hope that through this article, you can better understand how to use CSS to achieve adaptive width and height of images, and become more comfortable in website development.

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