@avlidienbrunn reported an issue where user-supplied HTML elements with name attributes matching DOM variables would prevent JavaScript from accessing those variables. For example, an element like <img src='something.png' name='querySelector'> would cause JavaScript references to document.querySelector to return the image element rather than the querySelector function. Overwriting certain variables would break GitHub’s JavaScript and in some cases cause the browser to become unresponsive.

We addressed this issue by prefixing all user-supplied name attributes in markup with user-content-. To ensure that links to user-supplied named elements on the page still functioned properly, we used JavaScript to find and scroll to the element referenced by the fragment portion of the URL.