ggplotly-size fixed in shiny? Resizing doesnt work

I try to refit this shiny app for my purposes. Since I want to add some text above it, I use the Rmd-Format. The following code is completely the same as in the link, except that I deleted the server- and ui-functions, because otherwise you dont see all the output. (Update: I also threw out the click,zoom and brush-events, to make the code more readable)

```{r cars, echo=FALSE}
library(plotly)
library(shiny)

fluidPage(
  radioButtons("plotType", "Plot Type:", choices = c("ggplotly", "plotly")),
  plotlyOutput("plot", height = "700px"),
  verbatimTextOutput("hover")
)

  output$plot <- renderPlotly({
    # use the key aesthetic/argument to help uniquely identify selected observations
    key <- row.names(mtcars)
    if (identical(input$plotType, "ggplotly")) {
      p <- ggplot(mtcars, aes(x = mpg, y = wt, colour = factor(vs), key = key)) + 
        geom_point()
      ggplotly(p) %>% layout(dragmode = "select")
    } else {
      plot_ly(mtcars, x = ~mpg, y = ~wt, key = ~key) %>%
        layout(dragmode = "select")
    }
  })

  output$hover <- renderPrint({
    d <- event_data("plotly_hover")
    if (is.null(d)) "Hover events appear here (unhover to clear)" else d
  })

```

I added height=700px to plotlyOutput, because I have a bigger dataset and a long legend in my ggplot-graph. However while the plotly graph adjusts - the ggplot-graph does not get bigger than ~500px.

According to this thread, this is an issue of ggplotly. The problem is that I need to set height=700px in plotlyOutput to stop the ggplotly-graph from overplotting my Text-output. What I am searching is either:

1. Another way to stop the overplotting than setting height=700px in plotlyOutput, or alternatively,
2. Another way to change the size of the ggplotly-graph

To achieve the latter I tried adding the height to ggplotly to the layout function afterwards. I even set autosize=FALSE in the corresponding layout. I also tried to specify the height in an extra renderUI-function.