To fix cross-browser compatibility issues, test your app in different browsers, use CSS resets, and consider polyfills for unsupported features.

Cross-browser compatibility issues can lead to inconsistent user experiences across different web browsers, making it essential to address these problems during development. Start by testing your web app in various browsers, including Chrome, Firefox, Safari, Edge, and even mobile browsers. Use browser testing tools like BrowserStack or Sauce Labs to easily simulate different environments. Identify any discrepancies in layout, functionality, or performance, and document them for further analysis. Next, implement CSS resets or normalize.css to ensure consistent styling across browsers. These tools help eliminate browser-specific default styles that can lead to unexpected behavior. After establishing a baseline for styles, focus on writing clean and semantic HTML and CSS. Use feature detection libraries like Modernizr to determine whether a browser supports certain features, allowing you to provide fallbacks for unsupported ones. For JavaScript functionality, consider using polyfills to fill in gaps for browsers that lack support for modern features like promises or fetch. Libraries like Babel can help you transpile ES6+ code into a format that is compatible with older browsers. Additionally, avoid using vendor-specific prefixes for CSS properties unless absolutely necessary, as this can lead to maintenance challenges. Instead, rely on standard properties and utilize tools like Autoprefixer to automate prefixing during your build process. Finally, keep abreast of browser updates and changes in compatibility as new features are introduced or deprecated. Regularly updating your application to align with modern web standards will help minimize compatibility issues. By following these steps, you can effectively address cross-browser compatibility issues and create a consistent experience for users across different platforms.