ngx-admin with Angular Material

### Issue type

**I'm submitting a

* [*] bug report
* [ ] feature request
* [ ] question about the decisions made in the repository

### Issue description

**Current behavior:**
A simple button in angular material with html
`Basic`

is rendered as

`Basic

`

**Expected behavior:**
While i tried to integrate angular material with ngx-admin.
Style.scss looks like below:

```
@import '~@angular/material/theming';
@include mat-core();
$candy-app-primary: mat-palette($mat-indigo);
$candy-app-accent: mat-palette($mat-pink, A200, A100, A400);
$candy-app-warn: mat-palette($mat-red);
$candy-app-theme: mat-light-theme($candy-app-primary, $candy-app-accent, $candy-app-warn);
@include angular-material-theme($candy-app-theme);
@include nb-theme-global();
```

Same html in ngx-admin & Angular material

` BASIC`

above html is rendered as:

`BASUC BTB`

I could in the source tab of chrome the angular material theme/styles are download properly.

In ngx-admin template the angular-material style are not loading properly and the output is not as expected as with Angular material.
Please guide me if some thing is missed in the styles.scss or any other settings.

### Other information:

node -v
v8.12.0

npm -v
6.4.1

OS: Windows 10
Browser: Chrome
Angular 7.0.3
Nebular 3.0.0