use fill:none instead of fill:transparent

`transparent` is not a valid [svg](http://www.w3.org/TR/SVG/painting.html#SpecifyingPaint) [color](http://www.w3.org/TR/SVG/types.html#DataTypeColor). Use `none` instead.
Merge pull request #1441 from tyrasd/patch-1

use fill:none instead of fill:transparent