title: Change color of selected tab in shinydashboard tabBox
body: <p>Is there a way to change the color that indicates the active tab of a shinydashboard tabBox? I have changed the "skin" of the dashboard to "red". While this affects the highlighted active tab of the sidebar, it does not seem to have an effect regarding the selected tab in a tabBox. </p>
  
  <p>I have only found solutions for changing the acutal background color of a selected tab (e.g., <a href="https://stackoverflow.com/questions/49358329/shinydashboard-change-background-based-on-selected-tab">Shinydashboard - Change background based on selected tab</a>), however, I could not find anything regarding the little line on top of a selected tab in a tabBox. In my examples, the selected tabs (Tab1, Tab3, Tab1) should have a red indicator instead of the blue one the have now. </p>
  
  
  
  <pre class="lang-r prettyprint-override"><code>    library(shiny)
      library(shinydashboard)
  #&gt; 
  #&gt; Attaching package: 'shinydashboard'
  #&gt; The following object is masked from 'package:graphics':
  #&gt; 
  #&gt;     box
  
      body &lt;- dashboardBody(
          fluidRow(
              tabBox(
                  title = "First tabBox",
                  # The id lets us use input$tabset1 on the server to find the current tab
                  id = "tabset1", height = "250px",
                  tabPanel("Tab1", "First tab content"),
                  tabPanel("Tab2", "Tab content 2")
              ),
              tabBox(
                  side = "right", height = "250px",
                  selected = "Tab3",
                  tabPanel("Tab1", "Tab content 1"),
                  tabPanel("Tab2", "Tab content 2"),
                  tabPanel("Tab3", "Note that when side=right, the tab order is reversed.")
              )
          ),
          fluidRow(
              tabBox(
                  # Title can include an icon
                  title = tagList(shiny::icon("gear"), "tabBox status"),
                  tabPanel("Tab1",
                           "Currently selected tab from first box:",
                           verbatimTextOutput("tabset1Selected")
                  ),
                  tabPanel("Tab2", "Tab content 2")
              )
          )
      )
  
      shinyApp(
          ui = dashboardPage(dashboardHeader(title = "tabBoxes"), skin = "red", dashboardSidebar(), body),
          server = function(input, output) {
              # The currently selected tab from the first box
              output$tabset1Selected &lt;- renderText({
                  input$tabset1
              })
          }
      )
  #&gt; 
  #&gt; Listening on http://127.0.0.1:7512
  </code></pre>
  
  <p><img src="https://i.imgur.com/hB0nZf3.png" alt=""></p>
  
  <p><sup>Created on 2019-10-18 by the <a href="https://reprex.tidyverse.org" rel="nofollow noreferrer">reprex package</a> (v0.3.0)</sup></p>
  
  <pre class="lang-r prettyprint-override"><code>devtools::session_info()
  #&gt; - Session info ----------------------------------------------------------
  #&gt;  setting  value                       
  #&gt;  version  R version 3.6.1 (2019-07-05)
  #&gt;  os       Windows 10 x64              
  #&gt;  system   x86_64, mingw32             
  #&gt;  ui       RTerm                       
  #&gt;  language (EN)                        
  #&gt;  collate  German_Germany.1252         
  #&gt;  ctype    German_Germany.1252         
  #&gt;  tz       Europe/Berlin               
  #&gt;  date     2019-10-18                  
  #&gt; 
  #&gt; - Packages --------------------------------------------------------------
  #&gt;  package        * version date       lib source        
  #&gt;  assertthat       0.2.1   2019-03-21 [1] CRAN (R 3.5.3)
  #&gt;  backports        1.1.4   2019-04-10 [1] CRAN (R 3.5.3)
  #&gt;  callr            3.3.2   2019-09-22 [1] CRAN (R 3.5.3)
  #&gt;  cli              1.1.0   2019-03-19 [1] CRAN (R 3.5.3)
  #&gt;  crayon           1.3.4   2017-09-16 [1] CRAN (R 3.4.2)
  #&gt;  curl             4.1     2019-09-16 [1] CRAN (R 3.5.3)
  #&gt;  desc             1.2.0   2018-05-01 [1] CRAN (R 3.5.1)
  #&gt;  devtools         2.2.1   2019-09-24 [1] CRAN (R 3.5.1)
  #&gt;  digest           0.6.21  2019-09-20 [1] CRAN (R 3.5.3)
  #&gt;  ellipsis         0.3.0   2019-09-20 [1] CRAN (R 3.5.3)
  #&gt;  evaluate         0.14    2019-05-28 [1] CRAN (R 3.5.3)
  #&gt;  fs               1.3.1   2019-05-06 [1] CRAN (R 3.5.3)
  #&gt;  glue             1.3.1   2019-03-12 [1] CRAN (R 3.5.3)
  #&gt;  highr            0.8     2019-03-20 [1] CRAN (R 3.5.3)
  #&gt;  htmltools        0.3.6   2017-04-28 [1] CRAN (R 3.5.1)
  #&gt;  httpuv           1.5.2   2019-09-11 [1] CRAN (R 3.5.3)
  #&gt;  httr             1.4.1   2019-08-05 [1] CRAN (R 3.5.3)
  #&gt;  jsonlite         1.6     2018-12-07 [1] CRAN (R 3.5.2)
  #&gt;  knitr            1.25    2019-09-18 [1] CRAN (R 3.5.3)
  #&gt;  later            0.8.0   2019-02-11 [1] CRAN (R 3.5.3)
  #&gt;  magrittr         1.5     2014-11-22 [1] CRAN (R 3.4.1)
  #&gt;  memoise          1.1.0   2017-04-21 [1] CRAN (R 3.4.1)
  #&gt;  mime             0.7     2019-06-11 [1] CRAN (R 3.5.3)
  #&gt;  pkgbuild         1.0.5   2019-08-26 [1] CRAN (R 3.5.3)
  #&gt;  pkgload          1.0.2   2018-10-29 [1] CRAN (R 3.5.1)
  #&gt;  prettyunits      1.0.2   2015-07-13 [1] CRAN (R 3.5.1)
  #&gt;  processx         3.4.1   2019-07-18 [1] CRAN (R 3.5.3)
  #&gt;  promises         1.0.1   2018-04-13 [1] CRAN (R 3.5.1)
  #&gt;  ps               1.3.0   2018-12-21 [1] CRAN (R 3.5.2)
  #&gt;  R6               2.4.0   2019-02-14 [1] CRAN (R 3.5.3)
  #&gt;  Rcpp             1.0.2   2019-07-25 [1] CRAN (R 3.5.3)
  #&gt;  remotes          2.1.0   2019-06-24 [1] CRAN (R 3.5.3)
  #&gt;  rlang            0.4.0   2019-06-25 [1] CRAN (R 3.5.3)
  #&gt;  rmarkdown        1.15    2019-08-21 [1] CRAN (R 3.5.3)
  #&gt;  rprojroot        1.3-2   2018-01-03 [1] CRAN (R 3.5.1)
  #&gt;  sessioninfo      1.1.1   2018-11-05 [1] CRAN (R 3.5.3)
  #&gt;  shiny          * 1.3.2   2019-04-22 [1] CRAN (R 3.5.3)
  #&gt;  shinydashboard * 0.7.1   2018-10-17 [1] CRAN (R 3.5.2)
  #&gt;  stringi          1.4.3   2019-03-12 [1] CRAN (R 3.5.3)
  #&gt;  stringr          1.4.0   2019-02-10 [1] CRAN (R 3.5.2)
  #&gt;  testthat         2.2.1   2019-07-25 [1] CRAN (R 3.5.3)
  #&gt;  usethis          1.5.1   2019-07-04 [1] CRAN (R 3.5.3)
  #&gt;  webshot          0.5.1   2018-09-28 [1] CRAN (R 3.5.1)
  #&gt;  withr            2.1.2   2018-03-15 [1] CRAN (R 3.5.1)
  #&gt;  xfun             0.9     2019-08-21 [1] CRAN (R 3.5.3)
  #&gt;  xml2             1.2.2   2019-08-09 [1] CRAN (R 3.5.3)
  #&gt;  xtable           1.8-4   2019-04-21 [1] CRAN (R 3.5.3)
  #&gt;  yaml             2.2.0   2018-07-25 [1] CRAN (R 3.5.1)
  #&gt; 
  #&gt; [1] E:/R_LIBS_USER
  #&gt; [2] E:/R-3.6.1/library
  </code></pre>