Heatmap: how to specify the cell base color instead of white?

Is there a way to change the color of the cells reaching the minimum value (white by default) when using a color gradient?

Example:

library(shiny)
library(apexcharter)

data("vaccines", package = "highcharter")
df <- vaccines %>% subset(year <= 1946)

ui <- fluidPage(
  apexchartOutput("heatmap")
)

server <- function(input, output) {
  output$heatmap <- renderApexchart({
    apex(df,
         aes(year, state, fill = count),
         type = "heatmap") %>% 
      ax_chart(animations = list(enabled = FALSE)) %>%
      ax_dataLabels(enabled=F) %>%
      ax_colors("#0000FF") %>%
      ax_plotOptions(heatmap = heatmap_opts(colorScale = list(min = min(df$count), max = max(df$count))))
  })  
}

shinyApp(ui = ui, server = server)

Submitting a minimum value below the actual dataset minimum value does not do the trick neither:

ax_plotOptions(heatmap = heatmap_opts(colorScale = list(min = min(df$count) - 1000, max = max(df$count))))

dreamRs / apexcharter

Heatmap: how to specify the cell base color instead of white? #34