And a websearch you see projects you can give new life for webmin virtualmin themes if you like.
http://skcript.github.io/better-authentic/
http://www.xenlayer.com/xenlayer-theme.html
And a lot more yup old but are open source as base with the themes from virtualmin themselves you have very much opportunities to code a them with almost in it as you want also the look and feel ux and so on.