mkdocs-material/material/.icons/fontawesome/regular/square-full.svg

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><!--! Font Awesome Free 6.1.2 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc.--><path d="M512 0v512H0V0h512zm-48 48H48v416h416V48z"/></svg>