Previously, <style> elements were added to the SVG files in order to make them responsive to light/dark theme changes in the online documentation. For these two diagrams, the reuse of elements via <use> causes additional styling considerations; Browsers attach the cloned element(s) referenced by <use> under a separate 'shadow' DOM, making them inaccessible to normal CSS rule propagation. However, CSS inheritance still allows to control styling across the shadow DOM boundary. To fix, explicitly enable CSS inheritance of the `fill` and `stroke` attributes of copied elements, and apply theme-aware style to the referencing <use> element instead. Move the default `fill` and `stroke` attributes from the source elements into the <use> elements as well. This seems to fix CSS inheritance in Firefox. Amends 8643ae7a766b0f1c24d11d2dc64af6f23c307ad0. Pick-to: 6.10 Change-Id: I966c0a50500b86fc994476e85340d1171a5fc0eb Reviewed-by: Matthias Rauter <matthias.rauter@qt.io>