title: Shinydashboard skin effect is not working after renderUI
body: <p>I am trying to render shinydashboard after login page but shinydashboard skin color is not showing.
  my code is as follow:</p>
  
  <p><strong>ui.r</strong></p>
  
  <pre><code>library(shinydashboard)
  library(shiny)
  uiOutput("page")
  </code></pre>
  
  <p><strong>Login.R</strong></p>
  
  <pre><code> library(shinydashboard)
  
  ui1Output &lt;-  function(id, label = "ui1") {
  
    shinyUI(fluidPage(
                        mainPanel( 
  
                                textInput("username","Username",placeholder ="UserName"),
                                passwordInput("password","Password", placeholder ="Password"),
                                actionButton("login", "Login")
                               )))
    }
  </code></pre>
  
  <p><strong>dashbaordpage.R</strong></p>
  
  <pre><code>library(shinydashboard)
   dashpageOutput &lt;- dashboardPage(
    dashboardHeader(title = "Basic dashboard"),
    dashboardSidebar(
      sidebarMenu(
        menuItem("Dashboard", tabName = "dashboard", icon = icon("dashboard")),
        menuItem("Widgets", tabName = "widgets", icon = icon("th"))
      )
    ),
    dashboardBody(
      tabItems(
        # First tab content
        tabItem(tabName = "dashboard",h2("Dashbaord")),
  
        # Second tab content
        tabItem(tabName = "widgets",
                h2("Widgets tab content")
        )
      )
    )
  </code></pre>
  
  <p><strong>global.R</strong></p>
  
  <pre><code>source('login.R') #login page
  source('dashboardPage.R')#dashbaordpage
  </code></pre>
  
  <p><strong>server.R</strong></p>
  
  <pre><code>library(shiny)
  library(shinydashboard)
  
  shinyServer(function(input, output,session) {
  
    output$page &lt;- renderUI({
      ui1Output('ui1Output')
  
    })
  
  
    observeEvent(input$login,
                 {
  
                   if(True)
                   {
                     output$page &lt;- renderUI(dashpageOutput)
                    }
                   else
                   {
                     Logged&lt;-F
                     showModal(modalDialog(
                       title = "Error",
                       "Enter Correct Username and password"
                     ))
                   }
  
                 })
  
  })
  </code></pre>
  
  <p>Details: when I going dashboard is showing but not with default skin color or any other skin color. I have tried <strong>skin='red'</strong> like wise option.</p>
  
  <p><a href="https://i.stack.imgur.com/gpvDM.jpg" rel="nofollow noreferrer">Image for reference how actually showing after login.</a></p>
  
  <p>Please help me.
  Thanks in advance.</p>