How does the background image of the WeChat applet fill the entire screen

1. In the wxss file of the page, set the style of the background image:

page{
    background-image: url(图片路径);
    background-size: 100% 100%;
    background-repeat: no-repeat;
}

2. In the json file of the page, set the style of the background image:

{
  "backgroundTextStyle": "dark",
  "backgroundColor": "#ffffff",
  "backgroundImage": "图片路径",
  "backgroundSize": "100% 100%"
}