feat: use background for thick code border

## Details

Previously we modified how code borders are generated to make them
more configurable. Part of this change replaced the usage of the space
`' '` as our padding character with a block `'█'`.

This works for the most part but has a couple of problems:
- requires inverting a highlight group which is more error prone
- text behaves like foreground so does not play nicely with blending

We now avoid doing this when adding `thick` borders, so use a space and
avoid inverting the highlight group, `thin` borders keep old behavior.

Author: MeanderingProgrammer

CHANGELOG.md

@@ -10,6 +10,10 @@
 - improve completions [#474](https://github.com/MeanderingProgrammer/render-markdown.nvim/pull/474)
   [3254863](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/3254863eb91fed3d9a7433b54327716528f1eacc)
 
+### Bug Fixes
+
+- resolve styles & presets in overrides [eec00fb](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/eec00fbfd7273cdfa0a1154dbef0bb983641eaf8)
+
 ### Collaborator Shoutouts
 
 - @Anaritus

doc/render-markdown.txt

@@ -1,4 +1,4 @@
-*render-markdown.txt*        For NVIM v0.11.3        Last change: 2025 July 31
+*render-markdown.txt*       For NVIM v0.11.3       Last change: 2025 August 04
 
 ==============================================================================
 Table of Contents                          *render-markdown-table-of-contents*

lua/render-markdown/health.lua

@@ -5,7 +5,7 @@ local state = require('render-markdown.state')
 local M = {}
 
 ---@private
-M.version = '8.6.10'
+M.version = '8.6.11'
 
 function M.check()
     M.start('version')

lua/render-markdown/render/markdown/code.lua

@@ -140,9 +140,10 @@ function Render:language(info, language, delim)
         return false
     end
 
-    local left = self:line():text(self.config.language_left, border_hl)
-    local right = self:line():text(self.config.language_right, border_hl)
-    local body = left:extend(text):extend(right)
+    local body = self:line()
+        :text(self.config.language_left, border_hl)
+        :extend(text)
+        :text(self.config.language_right, border_hl)
 
     local border = border_hl and self.config.language_border or ' '
     local width = self.data.body - delim.start_col
@@ -180,11 +181,14 @@ function Render:border(node, thin)
     elseif kind == 'hide' then
         self.marks:over(true, node, { conceal_lines = '' })
     else
-        local icon = kind == 'thin' and thin or '█'
+        local icon = kind == 'thin' and thin or ' '
+        if icon ~= ' ' then
+            highlight = colors.bg_as_fg(highlight)
+        end
         local block = self.config.width == 'block'
         local width = block and self.data.body - node.start_col or vim.o.columns
         self.marks:start('code_border', node, {
-            virt_text = { { icon:rep(width), colors.bg_as_fg(highlight) } },
+            virt_text = { { icon:rep(width), highlight } },
             virt_text_pos = 'overlay',
         })
     end
@@ -234,7 +238,8 @@ end
 function Render:padding(background)
     local col = self.node.start_col
     local start_row, end_row = self.node.start_row, self.node.end_row - 1
-    local empty, widths = {}, col == 0 and {} or self.node:widths()
+    local empty = {} ---@type integer[]
+    local widths = col == 0 and {} or self.node:widths()
     for i, width in ipairs(widths) do
         if width == 0 then
             empty[#empty + 1] = (start_row + i - 1)