I Finally Added Dark Mode, and It Forced Me to Fix More Than Colors

I am building DocBeacon, a doc sharing and tracking SaaS. People spend a surprising amount of time inside analytics dashboards, heatmaps, and reading paths, so dark mode kept coming up in feedback.

I used to treat dark mode as a "later" feature. Then I realized it is not really a theme choice, it is a UX quality signal. If someone is reviewing a proposal at night or checking engagement stats between calls, bright white screens feel rough, and it quietly makes the product feel less polished.

What surprised me: implementing dark mode exposed a bunch of small issues I had been ignoring.

Visual hierarchy: some charts looked fine in light mode but became unreadable in dark mode.

Empty states and loading states: subtle borders and skeletons basically vanished.

Heatmaps and highlights: colors that were "loud but acceptable" in light mode became distracting in dark mode, so I had to rethink contrast.

Icons and badges: a few "it is fine" UI decisions were suddenly not fine.

So now dark mode is basically my forced audit of the UI. It is still in testing, and I plan to ship it this week.

Question for other IH builders: do you treat dark mode as a conversion feature, a retention feature, or just table stakes? And when you shipped it, what broke in your UI that you did not expect?