Below the width of 768, I set the background image to fixed, but the actual effect does not work

Design help Layout & Design
1

WiFi- 2024-08-09 at 15.52.58@2x
WiFi- 2024-08-09 at 15.52.58@2x1920×1378 110 KB

Below the width of 768, I set the background image to fixed, and I can see the effect in the editor, but the actual effect of the published site does not work

Here is my site Read-Only: LINK
(how to share your site Read-Only link)