title: Separate background color for each plot in multiple plots
body: <p>I am trying to make striped plots (with altering white and grey background) when plotting 5 box plots in a row. Why is the background color not being applied to the whole plot in my code? The background color does change when I plot the box plots individually.</p>
  
  <pre><code>set.seed(42)
  dev.off()
  windows(width=6, height=4)
  par(mfrow=c(1,5))
  par(mar=c(2,4,1,1)) # bottom, left, top and right
  
  par(bg = 'white')
  boxplot(rnorm(20), ylab = "A")
  title(xlab="n = 54", line=0)
  
  par(bg = 'grey')
  boxplot(rnorm(20),  ylab = "B")
  title(xlab="n = 54", line=0)
  
  par(bg = 'white')
  boxplot(rnorm(20),  ylab = "C")
  title(xlab="n = 54", line=0)
  
  par(bg = 'grey')
  boxplot(rnorm(20),  ylab = "D")
  title(xlab="n = 26", line=0)
  
  par(bg = 'white')
  boxplot(rnorm(20),  ylab = "E")
  title(xlab="n = 6", line=0)
  </code></pre>
  
  <p><strong>To clarify, I want the area inside red rectangles in the figure below to be grey.</strong></p>
  
  <p><a href="https://i.stack.imgur.com/g4yX5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/g4yX5.png" alt="enter image description here"></a></p>