Complex sentence: CSS was introduced in December 1996 by the W3C to support presentation and layout; this allowed HTML code to be semantic rather than both semantic and presentational, and improved web accessibility, see tableless web design.
Split into simpler sentences: CSS was introduced in December 1996 by the W3C to support presentation and layout. This allowed HTML code to be semantic rather than both semantic and presentational, and improved web accessibility, see tableless web design.