CSS3 (Cascading Style Sheets, Level 3) is widely used on many sites, although with some developers may not be considering the differences CSS3 and earlier, as these nuances do not necessarily know, if we consider a single technology CSS – styles for processing (rendering) HTML-pages.
Consider the most popular features that appeared in CSS3:
border-radius – rounding corners for blocks (values can be defined as once for all angles and for each angle separately);
box-shadow – a shadow for blocks (internal or external);
text-shadow – the shadow of the text;
opacity – transparency for blocks;
function gradient of property background – transfusion of different colors;
the use of background image and background color while property background.
The main problem is the lack of CSS3 support in older browsers (some CSS3 properties are not supported even in new versions), the most “problematic” is Internet Explorer.