Particles in header

Thanks for the great package.

I want to add animation in the header of my dashboard. It works under body of the dashboard but not in header. I tried with tags$li(class='dropdown' in dashboardHeader( ) but it does not show the animation.

```
library(shiny)
library(particlesjs)

ui <- dashboardPage(

dashboardHeader(title = "Basic dashboard"),
dashboardSidebar(),
dashboardBody(

tags$li(class = "dropdown",
tags$div(
id="particles-target",
style = "position: absolute; height: 600px; width: 100%;"
),
particles(target_id = "particles-target")
),

# Boxes need to be put in a row (or column)
fluidRow(
box(plotOutput("plot1", height = 250)),

box(
title = "Controls",
sliderInput("slider", "Number of observations:", 1, 100, 50)
)
)
)
)

server <- function(input, output) {
set.seed(122)
histdata <- rnorm(500)

output$plot1 <- renderPlot({
data <- histdata[seq_len(input$slider)]
hist(data)
})
}

shinyApp(ui, server)

```