HarmonyOS CustomDialog底部默认间距

@Entry  
@Component  
struct bindsheet {  
  @State isShow: boolean = false  
  @Builder  
  myBuilder() {  
    Column() {  
      Button("关闭弹窗")  
        .margin(10)  
        .fontSize(20)  
        .onClick(() => {  
          this.isShow = false;  
        })//通过点击事件将isShow属性变为false，bindSheet弹窗关闭  
    }  
    .width('100%')  
    .height('100%')  
  }  
  
  build() {  
    Column() {  
      Button("打开弹窗")  
        .onClick(() => {  
          this.isShow = true  
        })  
          //通过点击事件将isShow属性变为true，bindSheet弹窗弹出  
        .fontSize(20)  
        .margin(10)  
        .bindSheet($$this.isShow, this.myBuilder(), {  
          detents: [SheetSize.MEDIUM, SheetSize.LARGE, 200],  
          backgroundColor: Color.Gray,  
          showClose:false, //不显示关闭按钮  
          enableOutsideInteractive: true, //允许交互，不显示蒙层  
          blurStyle: BlurStyle.Thick,  
          preferType: SheetType.CENTER,  
          shouldDismiss: ((sheetDismiss: SheetDismiss) => {  
            console.log("bind sheet shouldDismiss")  
            sheetDismiss.dismiss()  
          })  
        })  
    }  
    .backgroundColor("#ff578ddd")  
    .justifyContent(FlexAlign.Start)  
    .width('100%')  
    .height('100%')  
  }  
}