Fix code block background color issue by removing inline_theme

[modernchina123]

Problem

Code blocks display with gray background colors on each line in production, even though local preview shows correctly without backgrounds.

Root Cause

The inline_theme: base16 configuration in _config.yml causes Rouge to generate inline styles (style="background-color: ..."). Inline styles have higher CSS specificity than class-based styles, making it impossible to override with CSS rules, even with !important.

Solution

Removed inline_theme: base16 from _config.yml. Now Rouge will use CSS classes instead of inline styles, allowing our existing CSS rules in _includes/head.html to properly override background colors.

Changes

• Removed inline_theme: base16 from kramdown.syntax_highlighter_opts in _config.yml

Testing

• ✅ Local preview verified - code blocks display without line backgrounds

Notes

• This change should fix the production issue where code blocks show gray backgrounds on each line
• All existing CSS rules for removing backgrounds remain in place and will now work correctly