device-level media features are identical in a fresh realm
Check id media-surface-vs-realm
What an ordinary browser yields
All twenty-five device-level features identical in both realms. Viewport-scoped features (orientation, colour scheme, display mode) are shown but deliberately not asserted, because they legitimately differ.
What a detector infers
Media features are answered by the layout engine rather than by the JavaScript properties that describe the same machine, which is what makes them worth asking twice. This check takes twenty-five DEVICE-level features — the pointer and hover capabilities of the attached input hardware, colour gamut, dynamic range, monochrome and colour-index depth, forced-colours and inverted-colours accessibility state, update cadence — and evaluates them in both the page and a fresh iframe. Device capability belongs to the machine, not to a document, so every realm of one browser must answer identically. The split matters as much as the check. Media features answer questions about three different things, and only device capability is realm-invariant: `orientation` follows the viewport's aspect ratio, so a 1x1 probe iframe is legitimately a different orientation than a landscape window, and `prefers-color-scheme` follows the document's own color-scheme declaration, which about:blank does not inherit from the page. Both were measured differing on a completely stock Chrome. Asserting on them would have failed every real browser, so they are collected for the read-out and never compared — the check asserts only the twenty-five that were verified to agree.
How to resolve it
Nothing to fix if the answers agree. If they disagree, something is answering media queries for the page world while the layout engine keeps answering honestly one realm away — the durable fix is to give the browser the real capability rather than to rewrite its answer.
Read in the wild by
Kasada
Around 29 probes read media features — input capability, colour, accessibility state — resolved by the layout engine rather than by JS properties.
prefers_color_scheme, prefers_reduced_motion, prefers_contrast, any_hover, any_pointer, forced_colors, inverted_colors, color_gamut, dynamic_range, …
Kasada ips.js teardown — the full 427-probe listEvery attribution traces to a published artifact. See the sources and their limits.
Other checks in Capability surfaces
- the device-API family is present or absent as a unit
device-api-family-coherenceWeb Bluetooth, WebUSB, WebSerial and WebHID are one family on Chromium desktop - the same secure-context gating, the same desktop platforms… - Firefox resistFingerprinting announces itself when enabled
firefox-resist-fingerprinting-identifiableFirefox's privacy.resistFingerprinting substitutes CONSTANTS rather than randomness, and a constant is itself a fingerprint. - the CSS feature surface is identical in a fresh realm
css-surface-vs-realmWhich CSS properties, values and selectors an engine understands is decided when the browser is compiled. - the codec matrix is identical in a fresh realm
codec-surface-vs-realmcanPlayType answers come from the media stack compiled into the browser, and the shape of that matrix is genuinely informative: branded… - supported <input> types are identical in a fresh realm
input-surface-vs-realmAssigning an unrecognised type to an <input> element does not throw — the element silently falls back to reporting type "text". - emoji advance widths are identical in a fresh realm
emoji-surface-vs-realmEmoji do not render from the page's fonts but from a platform font supplied by the operating system — Segoe UI Emoji on Windows, Apple Color… - the Web Animations surface is identical in a fresh realm
animation-surface-vs-realmThe Web Animations API exposes a small, precisely specified surface: whether Element.animate exists, whether the timeline and KeyframeEffect… - the platform theme resolves the CSS system colours coherently
system-colors-vs-platformThe CSS system-colour keywords — Highlight, HighlightText, Canvas, CanvasText, ButtonFace, ButtonText, GrayText and their newer siblings…
Clearcote is a browser built for fingerprint coherence
It is a Chromium fork, maintained by the same people who wrote this reference. It ships as a compiled browser rather than as a stealth script injected into someone else's — which is a description of how it is built, and is not an argument about how it behaves on this check.
This audit takes no position on how Clearcote scores on Capability surfaces checks, on this one, or anywhere else. It has no baseline corpus of other people's fingerprints to rank you against and no vendor scoreboard — nearly every check is self-referential, asking one browser the same question through two independent APIs and reporting whether both answers can be true at once. It runs identically on any browser, including ours. Run it on yours and read the result yourself.
See the other checks in Capability surfaces — the family media-surface-vs-realm belongs to.