Add microbyte CSS Box Model

[ansharora28]

MicroByte Title: The CSS Box Model

Domain: Developer essentials,Front end

Scope of learning for learners: Learners will get an idea on how to deal with various CSS properties like borders,padding,display,margins and learn about CSS units like ems and rems.

Activities:
Open Chrome developer tools and see how everything on the given page is present inside a box.
Experiment by changing the properties of these boxes using chrome dev tools.
Recreate a given image using CSS properties.
See how CSS units differ and practically observe the differences they can make to an element.