Complex sentence: From April, 2008, the CSS Zen Garden website was not being actively developed, however on May 7,2013, for the tenth anniversary of the website, Shea opened up submissions again, focusing on HTML5, CSS3 and modern design principles.
Split into simpler sentences: From April, 2008, the CSS Zen Garden website was not being actively developed. However, on May 7,2013, for the tenth anniversary of the website, Shea opened up submissions again, focusing on HTML5, CSS3 and modern design principles.