I would argue that Emacs should the same behavior as web browsers, for 2
reasons:
- While it might seem nice to adapt text color to the surroundings, note
that the right-hand side example is in Emacs is still problematic, since
one can't really see the black square frame around the blue plot.
- It would be hard to argue with any SVG producer that their SVGs are
broken if browsers display them just fine.

For reference, here are the SVGs, which by the way where generated with
Python's matplotlib library as follows:

```
import matplotlib.pyplot as plt
plt.plot([1,2]); plt.savefig("x-white.svg")
plt.plot([1,2]); plt.savefig("x-transparent.svg", transparent=True)
```