Use light text for hero title in dark mode

[fflaten]

Suggest to keep hero title light even in dark mode.

Before:

After:

Also moves hero-specific styling to main page css module where the rest is.

[fflaten]

Just a suggestion/personal preference so feel free to close. What do you prefer? Felt out of place on the blue background when both button and logo are light.

[bravo-kernel]

Looks much better 👍