Dark mode is a user expectation in products and a stylistic choice on marketing sites, and confusing those two cases is where teams waste effort. The honest rule: interfaces people use for hours should respect their theme preference; brand sites should commit to whatever serves the brand, in one theme or two, done properly. Here is the decision and the craft.
When dark mode genuinely matters
Products and dashboards. Anything used daily, at length, or at night: users have a system preference and increasingly expect SaaS interfaces to follow it. Developer tools, analytics, and media products lead here, and in clinical software we shipped, charts and status colors were built to read correctly in both themes from day one, because a night-shift screen is a real use case, not an aesthetic.
Reading-heavy surfaces. Long-form content at night is where dark themes earn their comfort reputation, provided the typography is retuned rather than merely inverted.
When one strong theme wins
Marketing sites live or die on a distinct visual identity, and identity usually means commitment: our own site is deliberately paper-white with ink and one purple, in every lighting condition, because the editorial feel is the brand. Maintaining two themes doubles design and QA for every page; on a five-page brochure site that cost buys little. Skipping dark mode on a brand site is a valid design decision, not a gap, what matters is that the one theme passes contrast and loads fast for everyone.
Doing dark properly, if you do it
Dark mode is a second palette, not a filter. The craft rules: never pure black with pure white (use dark grays with softened text to control glare), desaturate brand colors that vibrate on dark grounds, re-verify every contrast pair because AA failures flip sides in the dark, lift elevation with lighter surfaces instead of shadows, and prepare images and logos for both grounds, transparent assets betray you here. Charts and status colors need their own dark calibration, or “critical red” becomes unreadable exactly where it matters.
The implementation that respects users
Honor the system preference by default, offer a manual toggle that remembers its choice, and never flash the wrong theme on load, the classic dark-mode bug. Built on design tokens, a second theme is a mapping exercise; built on hardcoded colors, it is a rewrite, which is the real reason to decide about dark mode before the build, not after.
The one-line decision
Product: support it, properly. Marketing site: commit to the theme that serves the brand, and spend the saved effort on speed and content. Deciding for your own build? hello@beconfidency.agency.
Thinking like this is the day job of our web design service.