In the 'harmonisations' tab in the variables explorer, the scroll bar is not clearly visible

[timcadman]

Is your feature request related to a problem? Please describe.
In the harmonisation tab in the variables explorer, when there are more cohorts than fit on the page there is a scroll bar to move to the right. However, it is not immediately obvious that this exists:

This is because it is displayed much lower down in the page:

Describe the solution you'd like
The scroll bar is moved up the page so it is visible below the bottom row of the table

[connoratrug]

please see original design as made by agency for proposed solution,

https://drive.google.com/drive/u/1/folders/1nCAasjDQZnqiuptTK3_3hyJL4QAV5h94