Detailed explanation of CSS flexible layout properties: flex and justify-content

Detailed explanation of CSS flexible layout properties: flex and justify-content

In modern web design, flexible layout (flexbox) has become a very useful layout method . Flexible layouts allow us to easily create adaptive and flexible layouts to fit a variety of screen sizes and device types. Two core properties, flex and justify-content, play an important role in flexible layout.

1. Flex attribute

The flex attribute is an attribute that defines a flexible layout container and is used to control the scalability of each sub-item in the flexible container. By setting different flex values, we can implement various adaptive layouts.

The flex property has three values:

1. flex-grow: Set the expansion ratio of the sub-item, the default is 0. When set to 0, it means no scaling; when set to a value greater than 0, it means scaling proportionally.
2. flex-shrink: Set the shrink ratio of the sub-item, the default is 1. When set to 0, it means no shrinkage; when set to a value greater than 0, it means shrinkage in proportion.
3. flex-basis: Set the base size of the sub-item, the default is auto. It can be set to a specific length value, or it can be set to auto, which means that the sub-item itself determines the size.

The sample code is as follows:

.container {
  display: flex;
  justify-content: center;
}

.item {
  flex: 1;
}

In this example, we set up a container and set the container as a flexible layout container by setting display: flex. Then align the sub-items horizontally and center-aligned by setting justify-content: center. The flex value of a child item is 1, which means that all child items expand and contract according to the same proportion.

2. Justify-content attribute

The justify-content attribute is used to adjust the alignment of sub-items in the flexible container. It controls the alignment of subitems on the main axis (horizontal direction).

The justify-content property has the following values:

1. flex-start: The child items are aligned at the starting position of the flex container.
2. flex-end: Subitems are aligned at the end of the flex container.
3. center: The sub-items are centered in the flex container.
4. space-between: Sub-items are evenly distributed in the flex container and the space between items is maintained.
5. space-around: The sub-items are evenly distributed in the flex container, with the same spacing before and after the items.

The sample code is as follows:

.container {
  display: flex;
  justify-content: space-between;
}

.item {
  flex: 1;
}

In this example, we set up a container and set the container as a flexible layout container by setting display: flex. Then set justify-content: space-between to evenly distribute the child items in the container and maintain the space between items.

CSS flexible layout properties flex and justify-content provide a very convenient way to implement adaptive and flexible layout. By leveraging these two properties, we can easily create layouts that adapt to different devices and screen sizes. In actual projects, we can rationally use these two attributes according to needs and design requirements to achieve the best layout effect.

To summarize, the flex property is used to control the scalability of sub-items, while the justify-content property is used to adjust the alignment of sub-items on the main axis. These two attributes are very important and commonly used attributes in flexible layout. By using them properly, we can easily achieve various adaptive layout effects.

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