title: R shiny: center and resize textInput
body: <p>I am trying to do something (or so I thought) relatively simple. I have a simple shiny page with just a textInput box and an actionButton.</p>
  
  <p>I want them both to appear in the center (vertically and horizontally) of the window.</p>
  
  <p>The way I've started going about it is to use a fluidPage with two fluidRows, one for each element:</p>
  
  <pre><code>library(shiny)
  library(shinyapps)
  
  shinyUI(fluidPage(theme = "bootstrap.css",
     fluidRow(
        column(8, align="center", offset = 2,
        textInput("string", label="",value = ""),
        tags$style(type="text/css", "#string { height: 50px; width: 100%; text-align:center; font-size: 30px;}")
        )
     ),
  
     fluidRow(
        column(6, align="center", offset = 3,
           actionButton("button",label = textOutput("prediction")),
           tags$style(type='text/css', "#button { vertical-align: middle; height: 50px; width: 100%; font-size: 30px;}")
        )
     )
  )
  )
  </code></pre>
  
  <p>I can get the button to appear in the center (horizontally) but not the textInput box. If I don't specify a width for the textInput, it is centered, but if I increase it extends it to the right and so no longer sits in the center. Ideally I'd like it to take up 100% of the width of the column (which is why I defined column size 8 and offset 2) just like the button, but when I specify a width as a percentage, it doesn't change.</p>
  
  <p>In addition to this I'd like both the textInput and button to appear in the vertical center of the window, but I don't know how to approach that apart from putting in a dummy fluidRow before the first one to eat up some space.</p>
  
  <p>Thanks for any help, I think I've probably spent more time trying to get this page to display properly than I have on the whole rest of the app.</p>