html
css
.logo-img path {
The answer from @Praveen is solid.
I couldn't get it to respond in my work, so I made a jquery hover function for it.
CSS
.svg path {
transition:0.3s all !important;
}
JS / JQuery
// code from above wrapped into a function
replaceSVG();
// hover function
// hover over an element, and find the SVG that you want to change
$('.element').hover(function() {
var el = $(this);
var svg = el.find('svg path');
svg.attr('fill', '#CCC');
}, function() {
var el = $(this);
var svg = el.find('svg path');
svg.attr('fill', '#3A3A3A');
});