How to write code to center a box in HBuilder?

To center a box, you can use the following method:

1. Set margin to auto;
   For example, your HTML code is as follows:
2. I am a box
3. The CSS code is written below:
4. The width and height of myBox are set to 200px, and it is centered using the margin property.
5. Use Flexbox layout (recommended):
   For example, your HTML code would be as follows:
6. I am a box
7. The CSS code is as follows:
8. Make sure the container has a height of 100% of the viewport to vertically center the box within.

Both methods can center the box, you can choose which one to use based on your actual needs.