Don't join the Dark Side!
All other github colorschemes fail to capture the real github theme. This one comes as close as I could take it.
Plug 'romgrk/github-light.vim'
let g:Lightline.colorscheme = 'github_light'
If you want a more traditional lightline look let the following.
let g:lightline#colorscheme#github_light#faithful = 0
Theme
Fugitive diff mode & Visual selection
Side-by-side diff
Terminal & Completion popup
Lightline
Lightline alternative