feat: resolve #7 theme_civilytics(): default to a transparent background, opt-in for Civilytics cream

R/theme.R

@@ -36,10 +36,9 @@
 #'   to [civilytics_colors]`["paper_2"]` (`#F2EDE4`).
 #' @param grid Character. Which major gridlines to draw: `"y"` (default,
 #'   horizontal only), `"x"` (vertical only), `"both"`, or `"none"`.
-#' @param paper_bg Logical. If `TRUE` (default), fill the plot and panel
-#'   backgrounds with the warm `paper` color. Set to `FALSE` for a
-#'   transparent background (useful for slides or overlay on colored
-#'   surfaces).
+#' @param paper_bg Logical. If `FALSE` (default), the plot and panel
+#'   backgrounds are transparent (`fill = NA`). Set to `TRUE` to fill them
+#'   with the warm `paper` color (the Civilytics cream canvas).
 #'
 #' @section Font size hierarchy:
 #' All text sizes are derived from `font_size` using relative scale factors.
@@ -68,22 +67,22 @@
 #' \dontrun{
 #' library(ggplot2)
 #'
-#' # Default editorial theme
+#' # Transparent background (default) — composites cleanly onto any surface
 #' ggplot(mpg, aes(displ, hwy)) +
 #'   geom_point() +
 #'   theme_civilytics()
 #'
+#' # Warm paper canvas (opt-in)
+#' ggplot(mpg, aes(displ, hwy)) +
+#'   geom_point() +
+#'   theme_civilytics(paper_bg = TRUE)
+#'
 #' # With both gridlines and brand colors
 #' ggplot(mpg, aes(displ, hwy, colour = class)) +
 #'   geom_point() +
 #'   scale_color_civilytics() +
 #'   theme_civilytics(grid = "both")
 #'
-#' # Transparent background for embedding
-#' ggplot(mpg, aes(displ, hwy)) +
-#'   geom_point() +
-#'   theme_civilytics(paper_bg = FALSE)
-#'
 #' # Larger text for poster or display
 #' ggplot(mpg, aes(displ, hwy)) +
 #'   geom_point() +
@@ -102,7 +101,7 @@ theme_civilytics <- function(
     accent       = unname(civilytics_colors["ember_600"]),
     strip_color  = unname(civilytics_colors["paper_2"]),
     grid         = c("y", "x", "both", "none"),
-    paper_bg     = TRUE) {
+    paper_bg     = FALSE) {
 
   grid <- match.arg(grid)
   half_line  <- font_size / 2

tests/testthat/test_theme.R

@@ -133,9 +133,16 @@ test_that("theme_civilytics uses brand ink color for text", {
   expect_equal(th$text$colour, unname(civilytics_colors["ink"]))
 })
 
-test_that("theme_civilytics uses brand paper color for plot background", {
+test_that("theme_civilytics has transparent background by default", {
   th <- theme_civilytics()
+  expect_true(is.na(th$plot.background$fill))
+  expect_true(is.na(th$panel.background$fill))
+})
+
+test_that("theme_civilytics paper_bg=TRUE opt-in fills with cream", {
+  th <- theme_civilytics(paper_bg = TRUE)
   expect_equal(th$plot.background$fill, unname(civilytics_colors["paper"]))
+  expect_equal(th$panel.background$fill, unname(civilytics_colors["paper"]))
 })
 
 test_that("theme_civilytics uses paper_2 for strip background by default", {