Troubleshooting flexdashboard scrollbars

solve.Rmd_

---
title: "Generated data demo"
output: 
  flexdashboard::flex_dashboard:
    orientation: rows
    vertical_layout: scroll
runtime: shiny
---

```{r setup, include=FALSE}
require(flexdashboard)
```


Column {.sidebar}
-----------------------------------------------------------------------

```{r}

selectInput("assignment", label="Assignment", 
            choices = LETTERS)

```



Row  {data-height=70}
------------------------------------
    
    

### Data 
    
```{r}

renderUI({
  
  "Data"
  
})
```


Row 
------------------------------------


### Assignment
    
```{r}

renderUI({

  fn = tempfile()
  rmarkdown::render( input = "test.Rmd", output_file = fn )  
  return(withMathJax(includeMarkdown(fn)))

})

```

test.Rmd_

---
title: "Untitled"
author: "Richard D. Morey"
date: "22 September 2016"
output: md_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```

## R Markdown

This is an R Markdown document. Markdown is a simple formatting syntax for authoring HTML, PDF, and MS Word documents. For more details on using R Markdown see <http://rmarkdown.rstudio.com>.

When you click the **Knit** button a document will be generated that includes both content as well as the output of any embedded R code chunks within the document. You can embed an R code chunk like this:

```{r cars}
summary(cars)
```

## Including Plots

You can also embed plots, for example:

```{r pressure, echo=FALSE}
plot(pressure)
```

Note that the `echo = FALSE` parameter was added to the code chunk to prevent printing of the R code that generated the plot.