Link colors in dark theme have too low contrast

[Fleker]

Taking a look at a page like /use in dark mode:

The background color is 212121. The color of links is 3F51B5. The content of the links can be hard to read in some scenarios.

Using a tool like WebAim's contrast checker this produces a contrast ratio of 2.34, not passing any standard for contrast. I'd suggest using a lighter color like A1A8DE in the same spectrum to be more visible.

[Fleker]

I was going to make a PR myself, but I'm not seeing where this light-mode/dark-mode logic gets applied when clicking on the theme button.

[shanejonas]

hi @Fleker,

Thanks for the report.

The theming comes from the base gatsby theme, probably should move over to open-rpc org at some point in the future, but right now it lives here: https://github.com/xops/gatsby-openrpc-theme

And more specifically: https://github.com/xops/gatsby-openrpc-theme/blob/master/src/themes/default.tsx