docs: add adr and note in contribution guideline about browser support

CONTRIBUTING.md

@@ -73,6 +73,11 @@ Please try to stick to this as much as possible. You can serve the SPA with
 you will get redirected to a login page where you can choose a persona. This
 will set a JWT in the local storage.
 
+We agreed on supporting only Chromium based browsers with their 2 latest major
+versions. This allows us to use features that are available for these browsers
+regardless of their support in other browsers. Therefore, please use Chrome or
+Edge for development.
+
 ### API
 
 The API is a NestJS application serving a GraphQL API. Please use the NX CLI to

docs/architecture-decisions/adr008-browser-support.md

@@ -0,0 +1,37 @@
+# ADR008: Browser Support
+
+## Status
+
+Accepted
+
+## Context
+
+Our legacy application has been experiencing issues with Firefox and other
+non-Chromium browsers. These issues have been causing delays in development and
+have been a source of bugs that are hard to track and fix. Moreover, we want to
+leverage the latest web features such as CSS nesting, which are best supported
+and regularly updated in Chromium browsers. Supporting only the latest 2
+versions of Chromium browsers (Chrome and Edge) will allow us to focus our
+efforts on a more narrow range of browsers, reducing the complexity of our
+development and testing processes.
+
+## Decision
+
+We will only officially support the latest 2 versions of Chromium browsers
+(Chrome and Edge). This means that while the application may still work in other
+browsers, we will not be spending resources on testing and fixing issues that
+are specific to those browsers.
+
+## Consequences
+
+- Development will be easier as we only need to consider the latest 2 versions
+  of Chromium browsers.
+- We can leverage the latest web features that are best supported in Chromium
+  browsers.
+- We will need to test the application in the latest 2 versions of Chromium
+  browsers.
+  [This is not possible with Playwright, which always tests against the latest stable version](https://github.com/microsoft/playwright/issues/14435).
+  Therefore, a small possibility of bugs in older versions remains.
+- Users using other browsers may experience issues.
+- We will need to clearly communicate this decision to our users and update our
+  documentation accordingly.