Debugging HTML and CSS can be a challenging yet integral part of web development, with common issues including syntax errors, cross-browser compatibility, and element outlining. Syntax errors, such as typos or incorrect tag closures, can be detected using validation tools like W3C's CSS Validator, though complex errors might require more detailed analysis with tools like CSS Lint. Cross-browser compatibility has become more significant with the rise of mobile devices, necessitating practices such as CSS normalization and ensuring HTML/CSS properties are universally supported to prevent discrepancies across different browsers. Additionally, tools like the Web Developer plugin and inbuilt browser developer tools can assist in outlining elements and toggling CSS properties to identify style inconsistencies, while adherence to W3C standards can mitigate issues arising from mixed display types. Debugging is an evolving skill that improves with experience, and thorough testing across devices and browsers is crucial before deploying a website to ensure functionality. The article is authored by Arnab Roy Chowdhury, a UI developer and experienced technical blogger.