font scale fix

markdown2html.py

@@ -107,7 +107,7 @@ def markdown2html(markdown, basepath, re_render, resources, viewport_width, font
             target_size = round(BASE_PX_SIZE * multiplier * font_scale)
             # Simple style setting (overwrites existing inline style if any)
             # A more robust solution would parse and merge existing styles
-            element['style'] = f"font-size: {target_size}px;"
+            element['style'] = "font-size: {}px;".format(target_size)
 
     # FIXME: report that ST doesn't support <br/> but does work with <br />... WTF?
     stylesheet = resources["stylesheet"] # Use only the base stylesheet