fix code snippets indendations

gui.py

@@ -93,7 +93,7 @@ def _highlight_code_lines(code: str, lang: str) -> list[str]:
             lexer = TextLexer()
     highlighted = highlight(code, lexer, _CODE_FORMATTER)
     lines = highlighted.rstrip("\n").split("\n")
-    return [f'<span style="color:{_CODE_FG};">{line}</span>' for line in lines]
+    return [f'<span style="color:{_CODE_FG}; white-space:pre;">{line}</span>' for line in lines]
 
 
 def _reset_cursor_format(cursor: QTextCursor) -> None: