change colour of selectizeInput options in R Shiny

Question

I would like to change the colour of each individual option of the selectizeInput menu in my Shiny app. In the following example code below I am able to change

Answer 1

Replacing my code with the above suggested code changed the drop down menu colour but NOT the individual items in the menu:

shinyApp(
  ui = 
    shinyUI(fluidPage(
      tags$head(
        tags$style(HTML("
        .option[data-value=a] {
          background: red !important;
          color: white !important;
        }
        .option[data-value=b] {
          background: green !important;
          color: white !important;
        }
  "))
      ),
      sidebarLayout(
        sidebarPanel(
          selectizeInput("select", label=NULL,
                         choices=c("a", "b"),
                         selected = c("a", "b"),
                         multiple=TRUE, options=list(placeholder="Wybierz"))),
        mainPanel())
    )
    ),
  server = function(input, output){}
)

SOLUTION In order to achieve both items colour coded and the drop down. I needed to add .item to my code

shinyApp(
  ui = 
    shinyUI(fluidPage(
      tags$head(
        tags$style(HTML("
        .option[data-value=a], .item[data-value=a]{
          background: red !important;
          color: white !important;
        }
        .option[data-value=b], .item[data-value=b]{
          background: green !important;
          color: white !important;
        }
  "))
      ),
      sidebarLayout(
        sidebarPanel(
          selectizeInput("select", label=NULL,
                         choices=c("a", "b"),
                         selected = c("a", "b"),
                         multiple=TRUE, options=list(placeholder="Wybierz"))),
        mainPanel())
    )
    ),
  server = function(input, output){}
)

This results in both the menu and drop down menu being coloured.

Answer 2

You can do:

.option[data-value=a] {
  background: red !important;
  color: white !important;
}
.option[data-value=b] {
  background: green !important;
  color: white !important;
}
.option[data-value=c] {
  background: blue !important;
  color: white !important;
}
.option[data-value=d] {
  background: magenta !important;
  color: white !important;
}