title: transparent box on to my leaflet map using shiny dashboard
body: <p>I'm working on a Shiny App that produce maps with several heat circles using specific longitudes and latitudes for each circle. I want to create a filter box with several inputs and put them on to the map (not next to, above or below the map) and I also want that box to become transparent (low opacity) if the user is not using it. An example of this exact same issue can be adressed using this Shiny App: <a href="https://shiny.rstudio.com/gallery/superzip-example.html" rel="nofollow noreferrer">https://shiny.rstudio.com/gallery/superzip-example.html</a></p>
  
  <p>Take into account that I am using Shinydashboard elements, but the example isn't. Until now, I haven't been able to modify the css style object that it presentes to the way I require.</p>
  
  <p>This is a reproducible peace of code:</p>
  
  <pre><code>### User Interface ----
  ui &lt;- dashboardPage(
   dashboardHeader(title = "Delitos"),
   dashboardSidebar(
     sidebarMenu(
       menuItem("Mapa", tabName = "mapa", icon = icon("th"))
     )
   ),
   dashboardBody(
     tabItems(
  
       tabItem(tabName = "mapa",
               fluidRow(
                 useShinyjs(),
                 tabBox(
                   id = "tabset_mapa",
                   selected = 1,
                   width = "100%",
                   tabPanel("Mapa",
  
                            leafletOutput("mapa1", width = "100%",
                                                 height = 565), value = 1,
  
                            selectInput(inputId = "tentativa_mapa",
                                        label= "Tentativa", 
                                        choices = c("Todos","Sí", "No")),
  
                            selectInput(inputId = "tipo_delito_mapa",
                                        label= "Presunto delito", 
                                        choices = c("assault", "robbery", "murder 1st grd", "racism")),
                            selectInput(inputId = "periodo_tipo_mapa",
                                        label= "Periodo", 
                                        choices = c("Anual", "Trimestral", "Mensual")),
  
                            selectInput(inputId = "provincia_mapa",
                                        label= "Nivel", 
                                        choices = c("National", "By province", "By city")),
  
                            downloadButton('downloadPlot_mapa','Descargar mapa'),
  
                            downloadButton('downloadTab_mapa','Descargar tabla')),
  
                   tabPanel("Tabla", tableOutput("datos_mapa"), value = 2)
                 )
            )
        )
      )
  )
  )
  
  server &lt;- function(input, output, session) {
  
   provinces_example&lt;-read.table(text="province  latitude    longitude   commited_crimes
                 'AZUAY' -2.977837402    -79.59862563    40
                 'BOLIVAR'   -1.608160425    -79.21881726    80
                 'CAÑAR' -2.62647275 -78.74661345    120
                 'CARCHI'    0.497518667 -77.93454964    160
                 'CHIMBORAZO'    -2.295557587    -78.74180743    180
                 'COTOPAXI'  -0.689132059    -79.07517499    200
                 'EL ORO'    -3.599779139    -80.08944846    40
                 'ESMERALDAS'    0.788046309 -79.85938815    80
                 'GALAPAGOS' -0.864657102    -91.18846265    120
                 'GUAYAS'    -1.946949383    -79.54741946    160
                 'IMBABURA'  0.325942394 -78.21791368    180
                 'LOJA'  -4.337267466    -79.60400106    200
                 'LOS RIOS'  -1.681021544    -79.66105689    40
                 'MANABI'    -0.90954183 -80.03392081    80
                 'MORONA SANTIAGO'   -3.364821478    -78.6528047 120
                 'NAPO'  -0.732803451    -77.72780304    160
                 'ORELLANA'  -0.949617383    -75.88180184    180
                 'PASTAZA'   -1.267547808    -77.24877698    200
                 'PICHINCHA' -0.004023516    -78.07462989    40
                 'SANTA ELENA'   -2.234427504    -80.89511306    80
                 'SANTO DOMINGO DE LOS TSACHILAS'    -0.042338801    -79.37282164    120
                 'SUCUMBIOS' 0.145724565 -77.23283688    160
                 'TUNGURAHUA'    -1.278333208    -78.74968472    180
                 'ZAMORA CHINCHIPE'  -3.935345655    -78.74906701    200",h=T,strin=F)
  
   observeEvent(input$periodo_tipo_mapa, {
     if (req(input$periodo_tipo_mapa)=="Anual") {
       shinyjs::show("periodo_input_mapa")
       shinyjs::hide("periodo_input_mapa_t")
       shinyjs::hide("periodo_input_mapa_m")
     } else if (req(input$periodo_tipo_st)=="Trimestral") {
       shinyjs::hide("periodo_input_mapa")
       shinyjs::show("periodo_input_mapa_t")
       shinyjs::hide("periodo_input_mapa_m")
     } else if (req(input$periodo_tipo_st)=="Mensual") {
       shinyjs::hide("periodo_input_mapa")
       shinyjs::hide("periodo_input_mapa_t")
       shinyjs::show("periodo_input_mapa_m")
     }
   })
  
   observeEvent(input$tabset_mapa, {
     if (req(input$tabset_mapa)==1) {
       shinyjs::show("downloadPlot_mapa")
       shinyjs::hide("downloadTab_mapa")
     } else {
       shinyjs::show("downloadTab_mapa")
       shinyjs::hide("downloadPlot_mapa")
     }
   })
  
  ###MAPA----
  
  canton_popup &lt;- paste0("&lt;strong&gt;Provincia: &lt;/strong&gt;", 
                          provinces_example$province,
                          "&lt;br&gt;&lt;strong&gt;Número de denuncias: &lt;/strong&gt;", 
                          formatC(provinces_example$commited_crimes, format="f", big.mark = ".",decimal.mark = ",", digits=0))
  
   output$mapa1 &lt;- renderLeaflet({
     leaflet(provinces_example, options = leafletOptions(minZoom = 0, maxZoom = 14))%&gt;%
       setView(lng = -80.0123274, lat = -2.3201641, zoom = 7)%&gt;%
       addProviderTiles("CartoDB.Positron")%&gt;%
       setMaxBounds(lng1 = -96, lat1 = 4,lng2 = -70, lat2 = -10)%&gt;%
       addTiles()%&gt;% addMarkers( lng = provinces_example$longitude,
                                 lat = provinces_example$latitude, 
                                       popup = canton_popup) %&gt;%
       addMiniMap(centerFixed = c(-0.4,-90.5), zoomLevelFixed = 6, toggleDisplay = TRUE)
   })
  }
  shinyApp(ui, server)
  
  </code></pre>