css adapts to the bottom safe area of iphonex

.safe-area-inset-bottom {
  padding-bottom: 0;  
  padding-bottom: constant(safe-area-inset-bottom); // 兼容 IOS<11.2
  padding-bottom: env(safe-area-inset-bottom); // 兼容 IOS>=11.2
}

Note: H5 sets the meta tag viewport-fit value to cover to be effective (the default of the applet), that is, the page content fills the visible window, and the non-default auto/contain value is only in the safe area.