expose alternate bg palette

lua/zenflesh/init.lua

@@ -6,10 +6,10 @@ local diff_bg_l = 0
 
 local darkness = vim.g.zenflesh_darkness
 if darkness == "stark" then
-	normal_bg = normal_bg.abs_da(3).sa(8)
+	normal_bg = p.bg_stark
 	diff_bg_l = -3
 elseif darkness == "warm" then
-	normal_bg = normal_bg.abs_li(3).de(12)
+	normal_bg = p.bg_warm
 	diff_bg_l = 3
 elseif darkness ~= nil then
 	local error_msg = "Unknown zenflesh_darkness value: " .. vim.inspect(darkness)

lua/zenflesh/palette.lua

@@ -1,9 +1,14 @@
 local lush = require "lush"
 local hsluv = lush.hsluv
 
+local sand = hsluv(39, 9, 9) -- sand
+local stone = hsluv(230, 10, 76) -- stone
+
 return {
-	bg = hsluv(39, 9, 9), -- sand
-	fg = hsluv(230, 10, 76), -- stone
+	bg = sand,
+	bg_stark = sand.abs_da(3).sa(8),
+	bg_warm = sand.abs_li(3).de(12),
+	fg = stone,
 	rose = hsluv(6, 62, 60),
 	leaf = hsluv(111, 47, 61),
 	wood = hsluv(32, 47, 58),