Web developers face significant challenges in ensuring cross-browser compatibility due to the variety of browsers and their different rendering engines. This complexity is compounded by developers' innate browser preference biases, often favoring widely used ones like Google Chrome. Despite the dominance of certain browsers, it remains essential for developers to accommodate less popular ones, such as Internet Explorer, to reach all potential users effectively. Two primary approaches to manage browser compatibility are Graceful Degradation and Progressive Enhancement, with the latter generally preferred for building a universal base experience first. Developers can leverage CSS's fault tolerance to handle unsupported properties and utilize tools like Modernizr and feature queries for browser feature detection, enhancing consistency across platforms. Modernizr, a JavaScript library, offers extensive support for detecting next-gen HTML and CSS features, while native CSS feature queries (@supports) provide a more lightweight solution but lack support in older browsers like Internet Explorer. Despite these advancements, comprehensive cross-browser testing remains indispensable for validating website functionality across various browsers and versions, ensuring a seamless user experience.