pidgin/nest

c1fbb1f6b8e5
WCAG 2 fixes for contrast and empty header

Testing Done:
Ran WAVE tool browser extension. They have a no-install, web version at https://wave.webaim.org/

As an example, improvement goes from 3+24 errors to 2+0 errors on https://pidgin.im/contact/

The colors are directly-scaled, viable suggestions, but it would be possible to make the green more green by exchanging red/blue for green while maintaining the same level of contrast. As an example #0c8a0c might be a bit more vibrant green. Please let me know if you would like me to suggest other slight color variations.

Bugs closed: NEST-45

Reviewed at https://reviews.imfreedom.org/r/777/
[
"Afrikaans",
"Albanian",
"American English",
"Amharic",
"Arabic",
"Armenian",
"Australian English",
"Azerbaijani",
"Belarusian Latin",
"Bengali",
"Bokmal Norwegian",
"Bosnian",
"British English",
"Bulgarian",
"Canadian English",
"Catalan",
"Chinese",
"Czech",
"Danish",
"Dutch",
"Dzongkha",
"English",
"Esperanto",
"Estonian",
"Euskera (Basque)",
"Finnish",
"French",
"Galician",
"Georgian",
"German",
"Greek",
"Gujarati",
"Hebrew",
"Hindi",
"Hong Kong Chinese",
"Hungarian",
"Indonesian",
"Irish",
"Italian",
"Japanese",
"Kannada",
"Khmer",
"Korean",
"Kurdish",
"Lao",
"Lithuanian",
"Macedonian",
"Malay",
"Marathi",
"Mongolian",
"Myanmar (Burmese)",
"Nepali",
"Norwegian Nynorsk",
"Occitan",
"Oriya",
"Pashto",
"Persian",
"Polish",
"Portuguese",
"Portuguese-Brazil",
"Punjabi",
"Romanian",
"Russian",
"Serbian",
"Serbian Latin",
"Simplified Chinese",
"Sinhala",
"Slovak",
"Slovenian",
"Spanish",
"Swahili",
"Swedish",
"Tamil",
"Telugu",
"Thai",
"Traditional Chinese",
"Turkish",
"Ukrainian",
"Urdu",
"Valencian-Catalan",
"Vietnamese",
"Xhosa"
]