Make font size dynamic

Author: Kathryn Dale

metrics/interfaces/charts/common/chart_output.py

@@ -44,9 +44,10 @@ def _apply_watermark(self) -> None:
         watermark_text = DataClassification[self.data_classification].value
 
         width = self.figure.layout.width or 800
+        
+        max_font_size = int((width * 0.9) / (len(watermark_text) * 0.5))
 
-        WATERMARK_FONT_SIZE = max(20, int(width * 0.07))
-
+        WATERMARK_FONT_SIZE = max(12, min(max_font_size, 100))
 
         self.figure.add_annotation(
             text=watermark_text,