Fix widget compatibility in Edge and Firefox to match Chrome behavior

Expected Behavior As an end user on Microsoft Edge and Mozilla Firefox, I want the widget to load, render, and function exactly as it does in Google Chrome so that interactions, visuals, and performance are consistent across supported browsers. Widget initializes without errors. UI renders correctly with no missing styles or layout shifts. All interactions (clicks, inputs, scrolling, resizing) work as expected. No browser-specific console errors or fallbacks needed by the user. Current Behavior In Edge and Firefox, the widget intermittently fails to initialize or renders a blank/partial UI. Some controls are unresponsive (e.g., buttons or inputs do not fire handlers, or resize/scroll observers do not trigger). Console shows browser-specific errors (e.g., undefined properties or unsupported methods) that do not occur in Chrome. Visual differences appear (layout shifts, missing styles/prefixes) compared to Chrome. Possible Solution Audit and remove Chrome-specific APIs; add feature detection and fallbacks (e.g., use navigator.userAgentData fallback, replace non-standard event.path with Event.prototype.composedPath, avoid webkit-prefixed CSS where standards exist). Update browserslist targets and ensure transpilation/polyfills for Edge/Firefox via build pipeline (e.g., core-js polyfills for modern DOM/Intl features; verify ResizeObserver/MutationObserver usage; ensure pointer/mouse/touch events are handled consistently). Run cross-browser tests and linting (e.g., Sauce/BrowserStack) and add CI to prevent regressions. Verify CSS compatibility (Autoprefixer/PostCSS) and avoid selectors/features not yet supported in Firefox/Edge without fallbacks. Steps to Reproduce Open Microsoft Edge (latest stable) or Mozilla Firefox (latest stable/ESR) on Windows or macOS. Start a private/incognito session or clear cache to avoid cached scripts. Navigate to any page that embeds the widget. Observe: widget fails to load or partially renders; open the browser console to see errors and attempt interactions (clicks, inputs, resize/scroll) to confirm non-parity with Chrome. Context (Environment) Affects users on Edge and Firefox (latest stable/ESR) across Windows 10/11 and macOS. Causes inconsistent experiences and potential conversion loss for non-Chrome users. Goal is functional and visual parity with Chrome, with zero console errors and identical behavior across supported browsers.