Using CSS to transition the fill property of an SVG path on hover

Answer 1

In order to transition/fade, CSS needs a starting value and an ending value.
Because you set the color for the path using the SVG attribute fill="#FAFAFA", CSS doesn't process it and the transition doesn't fade.

Instead if you use CSS to set the color, the transition will behave as expected

So all I had to do to make the transition work is give the #europe a starting fill to transition from.

 path { transition: fill .4s ease; }
 /* set fill for before and for during hover */
 #europe       path { fill: red; }
 #europe:hover path { fill: white; }

Here's a working JSFiddle.

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Or, doing it inline can be more convenient (style=""):

Just in order for CSS to do your fading, it needs to handle the start and end values in CSS/inline style (as opposed to using the SVG fill= attribute).