dcim: fix #3964 by moving away from properties to inline styles

netbox/dcim/models/__init__.py

@@ -395,7 +395,7 @@ class RackElevationHelperMixin:
                 fill='black'
             )
         )
-        link.add(drawing.rect(start, end, fill='#{}'.format(color)))
+        link.add(drawing.rect(start, end, style='fill: #{}'.format(color), class_='slot'))
         hex_color = '#{}'.format(foreground_color(color))
         link.add(drawing.text(device.name, insert=text, fill=hex_color))