How do you keep HTML and CSS organized in large projects?

When working on larger web projects, keeping HTML and CSS clean and organized becomes essential for collaboration and long-term maintenance. Some developers prefer using methodologies like BEM (Block Element Modifier) for CSS, while others rely on component-based structures or frameworks. Naming conventions, separating concerns, and avoiding deeply nested elements can make a big difference. How do you personally approach organizing your code to keep things scalable and easy to manage?