A few of the most important CSS3 modules are:
This CSS module defines the box model for the elements it considers the differences between vertical and horizontal rendering. In the flex layout model, the container can be laid out in any direction, and can "flex" or resize itself either growing to fill the space or shrinking to avoid overflowing each other. Both horizontal and vertical alignment of the spaces can easily be manipulated. Nesting can be used to build layouts in two dimensions.
CSS3 Flexible Box Layout Explained
Read about CSS3 borders at W3schools.com
Multiple Backgrounds are the most fun and challenging. Just remember when layering the first image is on top and they go down from there. The box that is your base layer, the most opaque, list that one last. Older browser’s do not support multiple backgrounds so use Modernizr.
<bg-image> = <image> | none
this sets the background image(s) of an element. The Images are drawn with the first one on top (closest to the user) and each subsequent image behind the previous one. Think Photoshop layers!
A value of ‘none’ will count as an ‘ image layer’ yet draws nothing. An image that is empty (missing) also counts as a layer but draws nothing.
Each image is positioned, sized, and tiled according to the value in the other background properties. They are matched up from the first value.
Places to learn more about this feature:
Quick note about Opacity
CSS3 keyframes explained
A web page may have different styles sheet depending on the device it is viewed with. Below are few articles that explain the concepts with examples.
There is no need for me to rewrite all of the great content you can find on selectors, here are some of the best I found:
codrops has a nice tutorial for a simple CSS icon hover effect. The uses a subtle and stylish effect using CSS transitions + animation on the anchor and their pseudo-elements. There are a variety of effects complete with a demo and code download.
CSS3 is the latest version of CSS. “CSS” is an acronym for Cascading Style Sheets, a markup language that describes the rendering of structured documents telling the browser how to render the look and layout of a website. CSS3 offers a wonderful variety of new ways to display content with high visual impact to users across many devices.