Dark mode gets handled as a token system rather than a second design. Every colour in the product points to a named token, each token holds one value per theme, and switching themes swaps the value set, so a thousand screens change together from a single file instead of being repainted one by one.
Token discipline decides whether theming stays maintainable, because products that hard-code colours into individual screens face a manual hunt across every file when a theme arrives later. Teams among the best ai product design agencies build the token layer before drawing a single themed screen, and scanning tools guard it afterwards by flagging any new screen that ships a raw colour value instead of a token reference, catching drift at the moment it appears rather than during a painful cleanup a year on.
Why is dark mode not inverted light mode?
Dark mode fails when treated as flipped light mode, because pure inversions produce glowing white text on true black that strains reading, shadows that make no sense against dark surfaces, and brand colours that lose their character against the changed background they now sit on.
Adjustments follow readability rules instead, with dark surfaces set to deep grey rather than true black, text dropped slightly below pure white, and elevation shown through lighter surface layers rather than shadow, since shadow reads poorly in dark settings. Brand colours get re-mixed per theme too, because a blue tuned for white backgrounds often fails contrast checks against grey, so the token file holds a shifted value keeping the same recognisable character while passing every reading test.
How are both themes tested?
Both themes get tested as equals through the same full check suite, since teams that treat dark mode as an afterthought ship it with faults the light theme never had, and users who chose dark mode meet those faults every single session.
Automated contrast scans run across every screen in both themes on every release, measuring each text-and-background pairing against reading thresholds and failing the build when any pairing drops below them. Humans pass the scans with reviewers working full flows in each theme separately, catching the faults machines miss, such as an illustration that vanishes against the dark surface or a chart whose lines become indistinguishable once the background changes beneath them.
What keeps the brand recognisable across themes?
Brand recognition survives theming when identity rests on more than surface colour, so teams anchor it in the logo treatment, the type voice, the spacing rhythm, and the illustration style, which all carry across themes unchanged while the surface palette shifts around them.
Theme settings respect the user’s device preference by default while offering a manual override that persists across sessions, and scheduled switching follows the system clock, where the person enabled it. Every new feature ships in both themes from its first release, because a feature arriving light-only tells dark mode users their choice ranks second, and the token system makes shipping both nearly free once the discipline holds.
Theming built on tokens, adjusted values, equal testing, and stable identity marks gives users a genuine choice between two complete designs. Products holding that standard read comfortably in any light a person happens to sit in, which is what the setting exists to provide.