Collapse device buttons in navigation's top bar region

Problem / Motivation

Once the viewport narrows, navigation's tools region has to fit all of its items into a shrinking column. The responsive-preview bar has no shrink strategy, so the buttons are displayed below each other.

Steps to reproduce

1. Install Drupal core's Navigation module + responsive_preview_navigation.
2. Edit a node
3. Narrow the viewport
4. Observe: device buttons are listed below each other

Proposed resolution

Collapse the buttons when there is not enough space for all of them in the tools region