Shinydashboard skin effect is not working after renderUI - r

Question

I am trying to render shinydashboard after login page but shinydashboard skin color is not showing.
my code is as follow:
ui.r
library(shinydashboard)
library(shiny)
uiOutput("page")
Login.R
library(shinydashboard)
ui1Output <- function(id, label = "ui1") {
shinyUI(fluidPage(
mainPanel(
textInput("username","Username",placeholder ="UserName"),
passwordInput("password","Password", placeholder ="Password"),
actionButton("login", "Login")
)))
}
dashbaordpage.R
library(shinydashboard)
dashpageOutput <- 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")
)
)
)
global.R
source('login.R') #login page
source('dashboardPage.R')#dashbaordpage
server.R
library(shiny)
library(shinydashboard)
shinyServer(function(input, output,session) {
output$page <- renderUI({
ui1Output('ui1Output')
})
observeEvent(input$login,
{
if(True)
{
output$page <- renderUI(dashpageOutput)
}
else
{
Logged<-F
showModal(modalDialog(
title = "Error",
"Enter Correct Username and password"
))
}
})
})
Details: when I going dashboard is showing but not with default skin color or any other skin color. I have tried skin='red' like wise option.
Image for reference how actually showing after login.
Please help me.
Thanks in advance.