Header

### Description
The header containing the logged in user’s avatar and the branding information.

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### CSS/SASS Variables
*Dependencies are included and configured as part of the provided Update Set.*

| Variable | Comments |
| -------- |:---|
| `$orbit-sidebar-width: 260px !default;` | The width of the right sidebar. |
| `$orbit-navbar-header-bg: $navbar-default-bg !default;` | The background color of the header. |