The remark-lint-no-multiple-toplevel-headings package is a linting rule for Remark, a popular Markdown processor. It enforces a single top-level heading (H1) per Markdown document, improving document structure and accessibility. By preventing multiple H1 elements, it promotes a clear hierarchy and navigation, aligning with best practices for semantic markup. This lint rule helps maintain consistent Markdown style and ensures that documents are well-organized for both human readers and automated tools. It enhances Markdown quality and readability by enforcing a single primary topic declaration.