HarmonyOS如何修改promptAction.showToast显示的toast样式？

showCustomOffsetToast(text : string, alignment:DialogAlignment, offset : Offset) {  
    let dialog : CustomDialogController = new CustomDialogController(  
      {  
        builder: customTextToast({label:text}),  
        autoCancel: false,  
        alignment: alignment,  
        maskColor: '#00000000',  
        backgroundColor: '#00000000',  
        customStyle: false,  
        offset: offset  
      }  
    );  
    dialog.open();  
    this.autoClose(dialog);  
  }  
  autoClose(dialog : CustomDialogController){  
  let timeId = setTimeout(() => {  
    dialog.close()  
    clearTimeout(timeId)  
  },1500);  
  }