OTBI layout performance tile how can i make the square border thicker?

Summary

OTBI layout performance tile how can i make the square border thicker?

Content

Hello

We have an OTBI with layout of a sum displayed in a ‘performance tile ‘.
The report displays in the dashboard layout- in a square - see attached file.
We would like to have a THICK border for the square .
The only was option for THICK on the border measure.

how can i make  the external border of the square - tile thicker? 

Thanks 
Revital.