Remember that scripting in CSS actually used to be a thing - IE used to have 'behavior' and 'expression' properties that would load external scripting code or e

Remember that scripting in CSS actually used to be a thing - IE used to have 'behavior' and 'expression' properties that would load external scripting code or execute inline JavaScript. 'behavior' was commonly used to fix some PNG-transparancy issues in early IE versions (pngfix.htc) and 'expression' was a much more powerful (and dangerous) version of current 'calc'.