Building on top of what Finesse wrote, here is a simpler way to target the svg and change it's gradient.
This is what you need to do:
Some benefits of using classes instead of :nth-child
is that it'll not be affected if you reorder your stops. Also, it makes the intent of each class clear - you'll be left wondering whether you needed a blue color on the first child or the second one.
I've tested it on all Chrome, Firefox and IE11:
.main-stop {_x000D_
stop-color: red;_x000D_
}_x000D_
.alt-stop {_x000D_
stop-color: green;_x000D_
}
_x000D_
<svg class="green" width="100" height="50" version="1.1" xmlns="http://www.w3.org/2000/svg">_x000D_
<linearGradient id="gradient">_x000D_
<stop class="main-stop" offset="0%" />_x000D_
<stop class="alt-stop" offset="100%" />_x000D_
</linearGradient>_x000D_
<rect width="100" height="50" fill="url(#gradient)" />_x000D_
</svg>
_x000D_
See an editable example here: https://jsbin.com/gabuvisuhe/edit?html,css,output