ES5, 2009, CSS 2.1, 2011. HTML is not the only standard for a web browser Also in that period, Microsoft was failing to comply with the standards for CSS 2, st

ES5, 2009, CSS 2.1, 2011. HTML is not the only standard for a web browser Also in that period, Microsoft was failing to comply with the standards for CSS 2, standardised in 1998, ES3, standardised in 1999, and PNG, standardised in 1996.