Where I did studies those subjects
https://github.com/osmarpetry/bootstrap-resposive-site
Everything that comes before or after an element, to make quotes without appearing in the html
Default is static, relative will make all children relative to it. Absolute will be absolute over all statics but will always obey the relative parent. Fixed will leave the fixed element relative to the browser window, it will not move even with scroll…
The block is the list element default, if inline it will make the list horizontal