The CSS thing.

1. css files must use UTF-8 encoding;

2. CSS code must be lowercase;

3. Constant values cannot be quoted unless the value contains spaces. such as: color: "Red" is wrong, should be removed from the quotation marks; font-family: "Century Gothic"; If the name contains spaces, it must be quoted;

4. Background-img:url ("img.jpg"); The URL must be quoted if there is a space, otherwise it is not necessary;

5. Each line must end with a semicolon;

6. Note as/*...*/

7. The!important rule is added with the highest precedence. such as: color:red!important;

8. Box model (or box model). Each element will be rendered as one of the boxes in the browser. There are 6 main types of boxes:

• In-line frame (inline box)
• Inline block-level boxes (inline-block box)
• Block-level boxes (blocks box)
• Table boxes (table box)
• Absolute frame (Absolute box)
• Floating frame (floated box).

9. Elements that use the Float property are rendered as Inline-block.