Cascading Style Sheet - Key Concept

 CSS - Key Points

1.  jQuery css Selector and absolute CSS Selector are same and so richness in css selector
2. Concept of CSS Pseudo Classes (e.g, a:visited {background-color:green} -here :visited is called Pseudo class)
3. Relative and Absolute positioning 
4.  Multi-Classing (e.g, <div class=”module1 weather”>) and Grouping (e.g. h1, h2, p, q #content, .standard {color: #000; margin: 5px;})
5. Box Model =>width = content width + padding + border (not margin)
6. Float on any element disturbs the rest of the (parent) container after that element. So make float:clear before the element where normal flow is again expected
7. Concept of "Relatively Absolute" (Make the parent element relative and child elements as absolute - called relatively absolute to create column structure like float)

(Point 3 explained)

3. Relative and Absolute positioning :

• Relative postion called offset position creates a ghost element and relative means relative to the current position of the element in a normal flow. Browser see the element on the normal flow and mask it (blank as parent style) and then offset the element               
• Absolute positioning of an element is relative to the parent and space inbetween is contrasted and filled by other elements around it