Have to agree with @Archibald. Having most of the graphic in SVG but the blue outline in CSS means you switching rendering systems mid graphic. Which isn’t technically wrong - and there may be edge-cases where it makes sense - but for consistency and long term maintenance reasons, I’d probably keep in all in the same file (either CSS or SVG).
Stacking it like this with the cross as the meat in a circle sandwich. You can make the blue circle overlap the other shapes, so it’s impossible to get tiny fit issues like your original problem.