Developers are struggling with cross-browser compatibility issues due to the vast differences between browsers and their features. Internet Explorer is a major pain point, with only 4% market share but still being used by millions of people globally. CSS is another significant issue, with its complexity and unpredictability causing problems for developers. JavaScript is also a challenge, with different ECMAScript versions and native support issues across browsers. Rendering issues occur when elements work on one browser but not others due to differences in browser engines. Layout and styling issues are prevalent, particularly with CSS Flexbox and Grid, which can create design inconsistencies across browsers. Slow adoption of new features by browsers is a problem, as well as browser compatibility issues with Progressive Web Apps (PWAs). Polyfills are often tedious to write, but they are essential for maintaining consistent web applications across all platforms. The lack of perfect cross-browser compatibility is frustrating for developers, and the situation is expected to improve over time.