What are the rules of flexible layout?

The rules of flexible layout include: 1. Declaration of containers and items; 2. Main axis and cross axis; 3. Alignment and distribution; 4. Properties of flexible items; 5. Line wrapping and reverse; 6. Space Distribution and sizing; 7. Cross-axis order; 8. Cross-axis alignment; 9. Additional rules for flex containers; 10. Nested flex containers, etc. Detailed introduction: 1. Declaration of containers and items. In flexible layout, containers are used to contain items. The container can be any block-level element; 2. Main axis and cross axis. Items in flexible layout are arranged on the main axis and cross axis. ;3. Alignment and distribution, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

The rules of flexible layout mainly include the following aspects:

1. Declaration of containers and projects: In flexible layout, containers are used to contain projects. The container can be any block-level element, such as a div. In CSS, an element is declared a flex container by setting the display property to flex or inline-flex. The item is the element that needs to be laid out and can be any child element. Elements using flex layout automatically become flex items.

2. Main axis and cross axis: Items in the flexible layout are arranged on the main axis and cross axis. The direction of the main axis depends on the value of the flex-direction property, while the cross axis is perpendicular to the main axis. By setting the flex-direction property, you can define the direction of the main axis, thereby determining the arrangement direction of items.

3. Alignment and distribution: Alignment and distribution are important rules in flexible layout. The justify-content property can control the alignment of items on the main axis, while the align-items property can control the alignment of items on the cross axis. These properties can center the item horizontally and vertically, move it to the left or right, etc.

4. Properties of flexible items: Properties of flexible items include flex-grow, flex-shrink and flex-basis. flex-grow defines the enlargement ratio of the item when there is insufficient space, flex-shrink defines the shrinkage ratio of the item when there is excess space, and flex-basis defines the default size of the item. These properties can be used to control the scalability and resizing of the project.

5. Line wrap and reverse: By setting the flex-wrap attribute, you can control whether the item wraps or not. If set to flex-wrap: wrap, items will wrap within the container. In addition, you can use the flex-reverse attribute to reverse the order of items and implement reverse layout.

6. Spatial distribution and size adjustment: By setting the align-content and justify-content properties, you can control the spatial distribution and alignment of multi-line items. In addition, you can also use the flex-basis, flex-grow and flex-shrink properties to adjust the size of the item to achieve a more flexible layout effect.

7. Cross-axis order: In flexible layout, in addition to being determined by the main axis direction, the order of items can also be adjusted by setting the order of the cross-axis. The order in which items are arranged can be defined using the flex-start, flex-end, flex-left, and flex-right properties, which specify the starting or ending position of the items on the cross axis.

8. Cross-axis alignment: The alignment of the cross-axis can be set individually through the align-self attribute. This allows us to align items on the cross axis, overriding the alignment settings in the container. The align-self attribute can be set to auto, flex-start, flex-end, center, baseline or stretch.

9. Additional rules for elastic containers: For elastic containers, there are some additional rules that need to be followed. For example, a flex container can use the align-items and justify-content properties to control the alignment of items. Additionally, flex containers have an extra sub-item: flex separators. This separator can be used to control the spacing between items, and can be used to align the first item to the edge of the flex container and the last item to the edge of the flex container by setting justify-content: space-between;.

10. Nested flexible containers: In flexible layout, we can nest a flexible container within another flexible container. In this case, the inner container inherits the outer container's alignment, main-axis orientation, and wrapping properties. However, the cross axis of the inner container is always perpendicular to the main axis of the outer container.

The above are the basic rules of flexible layout. By flexibly using these rules, we can achieve various complex layout effects. In actual development, we also need to consider browser compatibility issues to ensure that our website can correctly render and use elastic layout on different browsers and devices.

The above is the detailed content of What are the rules of flexible layout?. For more information, please follow other related articles on the PHP Chinese website!