slight problem with leaflet and flexdashboard

[MySchizo Buddy]

Using the zoom button on a leaflet map causes the map height to increase, pushing any text above the map. This happens in Rstudio only and not in Firefox
Use this working code

---
title: "Quakes"
output: flexdashboard::flex_dashboard
runtime: shiny
---
```{r setup, include=FALSE}

library(flexdashboard)
library(leaflet)

data(quakes)
```


Load Data
=====================================  

### Location Map

```{r}

p("Following are quake locations.")

renderLeaflet({
  leaflet(data = quakes[1:20,]) %>% addTiles() %>%
  addMarkers(~long, ~lat, popup = ~as.character(mag))
})
```

Before and after images are attached.