How to extend the background in a shiny dashboard - r

Question

Here is a small (silly) code of a shiny dashboard application:
library(shiny)
library(shinydashboard)
ui <- dashboardPage(
dashboardHeader(),
dashboardSidebar(uiOutput("choices")),
dashboardBody()
)
server <- function(input,output) {
output$choices <- renderUI(radioButtons("blabla", NULL, 1:100))
}
shinyApp(ui = ui, server = server)
When you run this code, you see that if you scroll down, the nice background on the right hand side suddenly switches to black. How do I make sure that the background stays nice and uniform throughout the entire page, even if a scroll down and use ui-elements?

Answer 1

I know this is an old question, but I'm adding here for posterity. I did not find a fixed height to be satisfactory as it adds a permanent scrollbar.
Using .content-wrapper { overflow: auto; } seems to work as I expect. I.e.:
dashboardPage(
dashboardHeader(),
dashboardSidebar(
# ...
),
dashboardBody(
# ...
tags$head(tags$style(HTML('.content-wrapper { overflow: auto; }')))
)
)

Answer 2

Just overwrite fixed height to your .content-wrapper class.
library(shiny)
library(shinydashboard)
ui <- dashboardPage(
dashboardHeader(),
dashboardSidebar(
tags$head(tags$style(HTML('.content-wrapper { height: 3000px !important;}'))),
uiOutput("choices")),
dashboardBody()
)
server <- function(input,output) {
output$choices <- renderUI(radioButtons("blabla", NULL, 1:100))
}
shinyApp(ui = ui, server = server)