diff --git a/lua/mellifluous/highlights/custom_groups.lua b/lua/mellifluous/highlights/custom_groups.lua
index 0ac9ea1..011f11e 100644
--- a/lua/mellifluous/highlights/custom_groups.lua
+++ b/lua/mellifluous/highlights/custom_groups.lua
@@ -1,12 +1,5 @@
 local M = {}
 
-local function fallback_if_none(color, fallback_color)
-    if type(color) == "string" and color == "NONE" then
-        return fallback_color
-    end
-    return color
-end
-
 -- Any shared highlight groups that cannot be found in general highlights or
 -- treesitter highlights are created here.
 function M.get(colors)
@@ -17,11 +10,9 @@ function M.get(colors)
         MainKeyword = { fg = colors.main_keywords, style = config.styles.main_keywords or {} },
 
         IndentLine = function(bg)
-            bg = fallback_if_none(bg, colors.bg)
             return { fg = shader.replicate_shade(colors.bg, colors.fg5, bg) }
         end,
         IndentLineInactive = function(bg)
-            bg = fallback_if_none(bg, colors.bg)
             return {
                 fg = config.is_bg_dark and shader.replicate_shade(colors.bg, colors.bg4, bg)
                     or shader.replicate_shade(colors.bg, colors.dark_bg2, bg),
@@ -30,7 +21,6 @@ function M.get(colors)
 
         MenuButton = { fg = colors.ui_blue },
         MenuButtonSelected = function(bg)
-            bg = fallback_if_none(bg, colors.bg)
             local applied_bg = config.is_bg_dark and shader.replicate_shade(colors.bg, colors.bg4, bg)
                 or shader.replicate_shade(colors.bg, colors.dark_bg2, bg)
             return {
diff --git a/lua/mellifluous/init.lua b/lua/mellifluous/init.lua
index d415abd..92bd016 100644
--- a/lua/mellifluous/init.lua
+++ b/lua/mellifluous/init.lua
@@ -19,6 +19,7 @@ function M.load()
     local colors = require("mellifluous.colors").get_colors()
     local highlighter = require("mellifluous.utils.highlighter")
 
+    require("mellifluous.utils.shader").set_background_color(colors.bg)
     require("mellifluous.highlights").set(highlighter, colors)
     require("mellifluous.config").set_highlight_overrides(highlighter, colors)
 
diff --git a/lua/mellifluous/utils/shader.lua b/lua/mellifluous/utils/shader.lua
index c6373c0..24db30c 100644
--- a/lua/mellifluous/utils/shader.lua
+++ b/lua/mellifluous/utils/shader.lua
@@ -1,5 +1,7 @@
 local M = {}
 
+local bg_color
+
 local function clip(val, from, to)
     if val > to then
         return to
@@ -10,6 +12,11 @@ local function clip(val, from, to)
 end
 
 function M.replicate_shade(from_color, to_color, target)
+    -- assume bg_color for any transparent colors
+    from_color = from_color ~= "NONE" and from_color or bg_color
+    to_color = to_color ~= "NONE" and to_color or bg_color
+    target = target ~= "NONE" and target or bg_color
+
     local from_hsl = from_color:get_hsl()
     local to_hsl = to_color:get_hsl()
     local color = require("mellifluous.color")
@@ -52,4 +59,8 @@ function M.get_higher_contrast(color, amount)
     return color:darkened(amount)
 end
 
+function M.set_background_color(new_bg_color)
+    bg_color = new_bg_color
+end
+
 return M