Responsiveness not working

### Issue type

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

* [x] bug report
* [ ] feature request

### Issue description

**Current behavior:**
I have a simple sidebar with some menu items and a header and a layout-column. When page is resized the sidebar does not collapse or open as per responsive behavior. Its fixed. I added a menu button to toggle sidebar which works fine. I also subscribed to themeservice and logged the change in screen width, which is also working. so why the sidebar should behave responsively.

**Expected behavior:**
Responsiveness should work

**Steps to reproduce:**

Phoebus List





Page Content

**Related code:**

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### Other information:

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