Contrast ratios that are mathematically derived are not always nice or correct. It's notoriously hard to determine perceived brightness from hex codes. That sai

Contrast ratios that are mathematically derived are not always nice or correct. It's notoriously hard to determine perceived brightness from hex codes. That said, it might need some tweaking. I only spent a little time on it and I know it helps to revisit a color scheme a couple of times during different light circumstances.