Change color of action button - r

Question

I would like to know if it is possible to change the color of an actionButton within an observeEvent.
In ui I have :
actionButton("bell","",icon=icon("bell"),
class = "btn action-button",
style = "color: white;
background-color: blue")
In server.R, my observeEvent is :
observeEvent(data_moment[1,c("facebook")]=="NA", {
disable("bell")
})
What I want :
If data_moment[1,c("facebook")]=="NA" I would like to disable the bell button, and set its color to grey.
Do you know how I can do ?

Answer 1

Just add a css rule for disabled Buttons in you css file
.btn.disabled {
background-color: red;
}
if you don't have any separate css-file you can add it to your UI with a script tag like this
library(shiny)
runApp(shinyApp(
ui = fluidPage(
shinyjs::useShinyjs(),
tags$style(".btn.disabled {
background-color: red;
}"),
actionButton("test", "Test"),
actionButton("submit", "Choose")
),
server = function(input, output, session) {
observeEvent(input$submit, {
shinyjs::disable("test")
})
}
))

Answer 2

Based on this answer
Ui:
uiOutput("button")
Server:
output$button <- renderUI({
if(is.na(data_moment[1,c("facebook")])){
actionButton(inputId= "bell","",
style = "color: white;
background-color: ...;
")
disable("bell")
}
else {
actionButton(inputId= "bell","",
style = "color: white;
background-color: blue;
")}
})