Greetings,
Adding <base rel='nofollow' href="/"> to the HTML causes the diagram's gridlines not to appear. The cause of the problem is that the base tag applies to SVG references which are used to reference the gridlines pattern (full description and workaround here:
https://github.com/meanjs/mean/issues/1224 )
I applied the workaround by changing the reference to include the current full path so that the base tag would not apply to it. For example, if the diagram's ID is "diagram", the following code makes the gridlines appear:
$('#diagram_canvaspattern_gridline').attr('fill', `url(${location.pathname}${location.search}#diagram_canvaspattern_grid)`);
I propose adding the location pathname and search to the fill attribute url as part of the diagram building code to have it working out of the box when base tag is present.