The attr() function in CSS is a powerful function that allows you to use the value of an attribute of an HTML element as the value of a CSS property. This function is commonly used with the content property in pseudo-elements to display the value of an attribute on the page. The attr() function has been around for a while and is widely used in CSS. However, it was limited to only accepting a single argument: the name of the attribute whose value you wanted to use. On top of that, the value retur...