HTML Tutorial: How to Use Flexbox for Page Layout

HTML Tutorial: How to use Flexbox for page layout

Introduction:
When developing web pages, page layout is a crucial part. In order to achieve adaptive and flexible layout, Flexbox has become one of the most popular solutions. This tutorial will introduce the basic concepts and usage of Flexbox, and provide specific code examples for readers' reference.

1. What is Flexbox?
Flexbox (flexible box layout model) is a new feature of CSS3 that can simplify page layout and provide better flexibility and responsiveness. Make page layout more flexible by defining the behavior of containers and items.

2. Basic concepts of Flexbox

1. Container: The element whose display is set to flex or inline-flex is called a container, and the container is the root parent element of the Flexbox layout.
2. Item (Item): The child elements in the container are called items, and each item is assigned to a row (row) or a column (column) of the container.
3. Main Axis: The main direction of the container is called the main axis, which can be horizontal (row) or vertical (column).
4. Cross Axis: The direction perpendicular to the main axis is called the cross axis.

3. How to use Flexbox for page layout

1. Create a Flex container:
   To create a Flex container, just change the display attribute of the HTML element Set to flex or inline-flex. For example:

   <div class="container">
     <!-- 子元素 -->
   </div>

   CSS code:

   .container {
     display: flex;
   }

2. Set the main axis direction:
   You can set the arrangement direction of items in the Flex container through the flex-direction property. Commonly used values ​​are: row (arranged from left to right in the horizontal direction, default value), row-reverse (arranged from right to left in the horizontal direction), column (arranged from top to bottom in the vertical direction), column-reverse (arranged in the vertical direction) arranged from bottom to top).

   .container {
     display: flex;
     flex-direction: row;
   }

3. Define the alignment of items on the main axis:
   You can use the justify-content attribute to define the alignment of items on the main axis. Commonly used values ​​include: flex-start (left-aligned), flex-end (right-aligned), center (center-aligned), space-between (aligned at both ends, equal spacing between items), space-around (each equal spacing around items).

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

4. Define the alignment of items on the cross axis:
   You can use the align-items attribute to define the alignment of items on the cross axis. Commonly used values ​​include: flex-start (top alignment), flex-end (bottom alignment), center (center alignment), baseline (baseline alignment), stretch (stretch to fill the container).

   .container {
     display: flex;
     align-items: center;
   }

5. Set the line wrapping method of the item:
   If the items in the container exceed the size of the container, you can set the line wrapping method of the item through the flex-wrap attribute. Commonly used values ​​include: nowrap (no line wrapping), wrap (line wrapping, arranging items from the new line), wrap-reverse (line wrapping, arranging items starting from the last line).

   .container {
     display: flex;
     flex-wrap: wrap;
   }

6. Set the alignment of items on the cross axis:
   You can use the align-content attribute to define the alignment of multi-line items on the cross axis. Commonly used values ​​include: flex-start (top alignment), flex-end (bottom alignment), center (center alignment), space-between (alignment at both ends, equal spacing between lines), space-around (each line The surrounding spacing is equal), stretch (each line stretches to fill the container).

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

4. Summary:
This tutorial introduces the basic concepts and usage of the Flexbox layout model. Flexible page layouts can be achieved by defining the behavior of containers and items. I hope this tutorial will be helpful for you to learn and master Flexbox layout.

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