Nebular stepper scss override

I need to override the nebular stepper, as we know that when the any step completed then the "checkmark" icon displayed but my use case is different I need the number will still remained not checkmark icon but color will change as same as icon (i.e. # ffffff).

### Issue type

**I'm submitting a ...** (check one with "x")

* [ ] feature request

### Issue description
need help in nebular stepper, as we know that when the any step completed then the "checkmark" icon displayed but my use case is different I need the number will remain but color will change as same as icon (i.e. # ffffff).
**Current behavior:**

**Expected behavior:**


**Steps to reproduce:**

**Related code:**

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### Other information:

**npm, node, OS, Browser**
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**Angular, Nebular**
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Thanks in Advance !!