Particles in modalDialog

Hi.
I am trying to use particles as background in a modalDialog but nothing shows. What can be wrong? Code is below.

Ivo

```
library(shiny)
library(shinyparticles)

server <- function(input,output) {
output$ui <- renderUI({
showModal(modalDialog(
div(id="particles-target", h1("Hello World"),
style="height: 400px; width: 600px;"),
size="l"
))
})

}

ui <- fluidPage(
uiOutput('ui'),
particles(target_id="particles-target")
)

shinyApp(ui, server)

```