When working on my laptop the buttons at the lower right of the screen are not shown, i.e. in "PCB Layout" view there are no controls for the grid size or snapping; nothing is shown to the right of the Active Layer status bar box.
I have found a solution to this, so am posting here for anyone else having a similar problem since I couldn't find a solution to the problem by searching.
The solution is to make the width of the browser window wider than 1430 pixels. In my case this is wider than the screen resolution. Alternatively you can zoom out using the browser controls (e.g. Safari>View>Zoom Out) not the upverter controls.
This problem occurs for me regardless of the browser used (Safari 10.1 or Vivaldi 1.10.867.42)