I have a question about Heat Grid (with circle shape) in CDE.

My datasource result is like below.

| Zone | Value |
| AB | 58.1 |
| CD | 10 |

Value field can has float value 0~100.

I'd like to change Circle shape and color using reference value.

for example,
I'd like to set Yellow color when value is under 50,
and set Black color when value is over 50. ( in this case reference value is 50)

I found some example codes, and found shape.fillStyle.
but I don't know how to change color using reference Value.

please help me.