Can't seem to edit UI colours and theme?

### Issue type

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

* [x] bug report
* [ ] feature request

### Issue description

**Current behavior:**
Not sure if this is a bug or just me missing something but no one is helping out on stackoverflow. Trying to implement changes to my chat using the attributes here (https://akveo.github.io/nebular/docs/components/chat-ui/theme#nbchatcomponent) but my chat UI is still unchanged. I am putting these attributes directly into my .scss file and not sure i need to put them in a certain way. Any help on this issue would be great.
**Expected behavior:**
Chat UI should change as expected.
**Steps to reproduce:**
1. Use chat attribute from theme page in scss file
2. Run chatbot

**Related code:**

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### Other information:

**npm, node, OS, Browser**
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**Angular, Nebular**
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