title: Ghost bars in gghistogram + gganimate
body: <p>I am trying to make an animated histogram with the following code:</p>
  
  <pre><code>library(ggpubr)
  library(gganimate)
  
  p &lt;- gghistogram(df, x = "Idade", bins = 30,
     add = "mean", rug = T,
     color = "Género", fill = "Género",
     palette = c("#0073C2FF", "#FC4E07", "grey"), 
     xlab ="Idade (anos)", ylab = "(n)", 
     title = "Distribuição de Idades") + 
    theme(legend.position = "right")+ 
    theme_ipsum_rc(grid="Y",base_size = 16,axis_title_size = 14)+
    transition_states(Idade, wrap = F) + shadow_mark() + enter_grow() +  exit_fade() 
  
  animate(p,  nframes=100, fps = 10, renderer = gifski_renderer(loop = FALSE))
  </code></pre>
  
  <p>but I am getting different darker blue and red bars (ghosts) like this:</p>
  
  <p><a href="https://i.stack.imgur.com/G3eOL.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/G3eOL.gif" alt="Gosth histrogram bars in gganimante"></a></p>
  
  <p>I can't figure it out. Any ideas on how to remove the darker bars? Thanks!</p>