黑暗主题RMarkdown

Question

我在为RMarkdown文档设置Darkly主题时遇到问题。我得到的是浅绿色背景。有解决方案吗？见下文

---
title: "Untitled"
author:
date: "July 29, 2020"
output:
  flexdashboard::flex_dashboard:
   theme: darkly
runtime: shiny
---
  
  
  ```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```



```{r eruptions, echo=FALSE}
inputPanel(
  selectInput("n_breaks", label = "Number of bins:",
              choices = c(10, 20, 35, 50), selected = 20),
  
  sliderInput("bw_adjust", label = "Bandwidth adjustment:",
              min = 0.2, max = 2, value = 1, step = 0.2)
)

renderPlot({
  hist(faithful$eruptions, probability = TRUE, breaks = as.numeric(input$n_breaks),
       xlab = "Duration (minutes)", main = "Geyser eruption duration")
  
  dens <- density(faithful$eruptions, adjust = input$bw_adjust)
  lines(dens, col = "blue")
})
```