title: Change colour and size of font in header of tabBox
body: <p>Although I am not very familiar with CSS, I have been able to include it in my R code to change various elements of my shiny app. However, I am unable to work out which element I need to change in order to change the colour and size of the font in the header of my tabBox, which comes from the package shinydashboard. </p>
  
  <p>The other boxes in my app have headers with dark backgrounds and light fonts. I have been able to change the background of the tabBox header so it is dark (see below code), but there is no element I see that seems to affect the font.</p>
  
  <p>I can change the font size of the tab labels using <code>font-size</code> in the <code>body</code>, or I can change the colour of the text in the box using <code>color</code>. But I am not able to find anything that relates to the attributes of the header title itself!</p>
  
  <p>Thanks for your help. </p>
  
  <p>Example code: </p>
  
  <pre><code>library(shiny)
  library(shinydashboard)
  
  ui &lt;- dashboardPage(
    dashboardHeader(),
    dashboardSidebar(),
    dashboardBody(
      tabBox(title = "Title of box", 
             tabPanel("Tab A"),
             tabPanel("Tab B")),
      tags$head(tags$style(HTML('
                                /* tabBox background */                    
                                .nav-tabs-custom&gt;.nav-tabs {
                                background-color: #2F4858;
                                }
                               '
      )
      )
      )
    )
  )
  
  server &lt;- function(input, output, session) {
  
  }
  
  shinyApp(ui, server)
  </code></pre>