Tweak the default code highlighting theme

app/config.py

@@ -93,6 +93,9 @@ EMOJI_TPL = '<img src="/static/twemoji/{filename}.svg" alt="{raw}" class="emoji"
 
 _load_emojis(ROOT_DIR, BASE_URL)
 
+# TODO(ts): allow to override this
+CODE_HIGHLIGHTING_THEME = "friendly_grayscale"
+
 
 session_serializer = URLSafeTimedSerializer(
     CONFIG.secret,

app/utils/highlight.py

@@ -5,7 +5,9 @@ from pygments import highlight as phighlight  # type: ignore
 from pygments.formatters import HtmlFormatter  # type: ignore
 from pygments.lexers import guess_lexer  # type: ignore
 
-_FORMATTER = HtmlFormatter(style="vim")
+from app.config import CODE_HIGHLIGHTING_THEME
+
+_FORMATTER = HtmlFormatter(style=CODE_HIGHLIGHTING_THEME)
 
 HIGHLIGHT_CSS = _FORMATTER.get_style_defs()