setup: add ui config with transparent bg

This commit also setup highlight for EOF-char & Window-Separator to
match the highlight on Cursor-Line-Number. And sets auto-command
to reset colors after changing the colorscheme.

lua/core/autocommands.lua

@@ -11,3 +11,12 @@ vim.api.nvim_create_autocmd('TextYankPost', {
     vim.hl.on_yank()
   end,
 })
+
+vim.api.nvim_create_autocmd('ColorScheme', {
+  desc = 'Reset colors for some elemnts after changeing the colorscheme.',
+  group = vim.api.nvim_create_augroup('ElementsColorReset', { clear = true }),
+  callback = function()
+    vim.api.nvim_set_hl(0, 'WinSeparator', vim.api.nvim_get_hl(0, { name = 'CursorLineNr' }))
+    vim.api.nvim_set_hl(0, 'EndOfBuffer', vim.api.nvim_get_hl(0, { name = 'CursorLineNr' }))
+  end,
+})

lua/core/init.lua

@@ -4,3 +4,4 @@ require 'core.keymaps'
 require 'core.diagnostics'
 require 'core.autocommands'
 require 'core.lazy-nvim'
+require 'core.ui'

lua/core/ui.lua

@@ -0,0 +1,10 @@
+-- [[ UI Configs ]]
+-- set transparency
+vim.api.nvim_set_hl(0, 'Normal', { bg = 'none', ctermbg = 'none' })
+vim.api.nvim_set_hl(0, 'NonText', { bg = 'none', ctermbg = 'none' })
+vim.api.nvim_set_hl(0, 'SignColumn', { bg = 'none', ctermbg = 'none' })
+vim.api.nvim_set_hl(0, 'FoldColumn', { bg = 'none', ctermbg = 'none' })
+
+-- set WinSeparator & EndOfBuffer to match the highlight on cursor-line-number
+vim.api.nvim_set_hl(0, 'WinSeparator', vim.api.nvim_get_hl(0, { name = 'CursorLineNr' }))
+vim.api.nvim_set_hl(0, 'EndOfBuffer', vim.api.nvim_get_hl(0, { name = 'CursorLineNr' }))