why is this model (style=fill:green) used when something like (fill= "green") still performs the same function.

Answer 1

It's not more complicated. It's just CSS. Actually, using stylesheets can save you time if you set a certain style to a large group of elements. But then you have to move styles to an area called <defs>, not inline as SoloLearn does it.
Note: not all attributes can be set via CSS.

Answer 2

the context is in the coloring of the svg images. both codes can produce the sane result. but solo learn decided to use the former in their example. the style:fill green is more complicated. so why not just use the simpler one. fill="green". I tried it and it still works.

Answer 3

what?

Answer 4

In what context?