feat: use new style definitions for hl groups. Keep backward compatibility for string styles

lua/tokyonight/config.lua

@@ -1,17 +1,19 @@
 local M = {}
 
 ---@class Config
+---@field on_colors fun(colors: ColorScheme)
+---@field on_highlights fun(highlights: Highlights, colors: ColorScheme)
 local defaults = {
   style = "storm", -- The theme comes in three styles, `storm`, a darker variant `night` and `day`
   transparent = false, -- Enable this to disable setting the background color
   terminal_colors = true, -- Configure the colors used when opening a `:terminal` in Neovim
   styles = {
     -- Style to be applied to different syntax groups
-    -- Value is any valid attr-list value `:help attr-list`
-    comments = "italic",
-    keywords = "italic",
-    functions = "NONE",
-    variables = "NONE",
+    -- Value is any valid attr-list value for `:help nvim_set_hl`
+    comments = { italic = true },
+    keywords = { italic = true },
+    functions = {},
+    variables = {},
     -- Background styles. Can be "dark", "transparent" or "normal"
     sidebars = "dark", -- style for sidebars, see below
     floats = "dark", -- style for floating windows