fluidPage()和dashBoardPage()都是HTML模板，通过使用这两个，你正在使用HTML模板中的HTML模板，当然，如果你想这样做，你可以这样做。所以没有'这是这个应用程序的正确模板'。这一切都取决于你的喜好，而fluidPage()是一个几乎'空'的模板，dashBoardPage()已经定义了一些HTML/CSS元素，如果使用fluidPage()，则必须自己编写代码。
我的意思是plotOutput("distPlot")。你看，如果你注解掉这一行，那个空格就消失了。
请参见下面的代码示例：

library(shiny)
library(shinyjs)
library(shinydashboard)
library(shinyauthr)

# dataframe that holds usernames, passwords and other user data
user_base <- tibble::tibble(
  user = c("a", "user2"),
  password = sapply(c("a", "pass2"), sodium::password_store),
  permissions = c("admin", "standard"),
  name = c("User One", "User Two")
)

  
ui = dashboardPage(
    
     dashboardHeader(
      title = "Title"),
    
    dashboardSidebar(
      tags$div(class = "sidebar-text",style = "text-align: center; font-style: italic;"),
      fileInput("csvFile1", "Load file")),
    
    dashboardBody(
      
      # logout button
      div(class = "pull-right", shinyauthr::logoutUI(id = "logout")),

      # login section
      shinyauthr::loginUI(id = "login"),

      # # Sidebar to show user info after login
      # uiOutput("sidebarpanel"),
      # 
      # # Plot to show user info after login
      # plotOutput("distPlot") ,
      
      useShinyjs(),  # Initialize shinyjs
      
      tags$br(),
      actionButton("knitButton", "Generate report"),
      downloadButton("downloadReport", "Download report", class = "btn-primary", disabled = TRUE))
      
    ) 

server <- function(input, output, session) {
  
  credentials <- shinyauthr::loginServer(
    id = "login",
    data = user_base,
    user_col = user,
    pwd_col = password,
    sodium_hashed = TRUE,
    log_out = reactive(logout_init())
  )
  
  # Logout to hide
  logout_init <- shinyauthr::logoutServer(
    id = "logout",
    active = reactive(credentials()$user_auth)
  )
  
  
  observeEvent(input$knitButton, {
    # Check if two CSV files are uploaded and report options are selected
    if (
      !is.null(input$csvFile1) ) {
      # Show the loading screen
      shinyjs::show("loading")
      
      # Disable the knit button during knitting
      shinyjs::disable("knitButton")
      
      # Pathway to the RMarkdown code
      rmd_path <- "Rmarkdown.Rmd"
      
      knittedFile <- rmarkdown::render(
        rmd_path,
        output_file = "knitted_report.html",
        params = list(
          data1 = input$csvFile1$datapath ) )
      
      output$downloadReport <- downloadHandler(
        filename = paste0("Report.html") ,
        content = function(file) {
          file.copy(knittedFile, file)
        }
      )
      # Hide the loading screen
      shinyjs::hide("loading")
      
      # Show the "Ready" message
      shinyjs::show("ready")
      shinyjs::enable("downloadReport")
    }
  })
  
  
}

shinyApp(ui = ui, server = server)

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