Shiny dashboard with yellow sidebar

app.R

library(shiny)
library(shinydashboard)

ui <- dashboardPage(
  dashboardHeader(),
  dashboardSidebar(),
  dashboardBody(),
  tags$head(tags$style(HTML("
    .skin-blue .main-sidebar {
        background-color:  yellow;
                            }")))
)

server <- function(input, output) { }

shinyApp(ui, server)

Thank you a lot!

I didn't know about !important. It is excellent.