expose alternate bg palette

lua/zenbones/init.lua

@@ -6,10 +6,10 @@ local diff_bg_l = 0
 
 local lightness = vim.g.zenbones_lightness
 if lightness == "bright" then
-	normal_bg = normal_bg.abs_li(3).sa(6)
+	normal_bg = p.bg_bright
 	diff_bg_l = -4
 elseif lightness == "dim" then
-	normal_bg = normal_bg.abs_da(3).de(12)
+	normal_bg = p.bg_dim
 	diff_bg_l = 4
 elseif lightness ~= nil then
 	local error_msg = "Unknown zenbones_lightness value: " .. vim.inspect(lightness)

lua/zenbones/palette.lua

@@ -1,9 +1,14 @@
 local lush = require "lush"
 local hsluv = lush.hsluv
 
+local sand = hsluv(39, 12, 94)
+local stone = hsluv(230, 30, 22)
+
 return {
-	bg = hsluv(39, 12, 94), -- sand
-	fg = hsluv(230, 30, 22), -- stone
+	bg = sand,
+	bg_bright = sand.abs_li(3).sa(6),
+	bg_dim = sand.abs_da(3).de(12),
+	fg = stone,
 	leaf = hsluv(112, 72, 42),
 	water = hsluv(236, 84, 40),
 	rose = hsluv(4, 70, 40),