Bureau structure page

- Add bureau structure page contents.
- Add content slider functionality for mobile org chart.
- Add jump-link__back & jump-link__bg modifiers.
I think the issue is that the `.content-hide` buttons don't share any classes with the `.content-show` ones at the moment. I could create a common class -- maybe around function (org chart/content slider target) or style (link styled button). Without more use cases, it's hard to say whether/how these styles would be reused. Any thoughts?