Firefox and Microsoft Edge Nested css Issue

[AT41]

• C3 version: 0.6.12
• D3 version: 5.9.1
• Browser: Firefox v65.0.1, Microsoft Edge v44.17763.1.0
• OS: MacOS Mojave v10.14.3

Problem Description: See http://jsfiddle.net/noy23p6a/ for reproduction of bug.
c3 automatically sets padding for the legend items, but on Firefox and Edge it doesn't automatically set padding and position for nested css styling. Opening the link using Chrome and Safari works, but not for Firefox and Edge.

Thanks!