This lightline.vim theme is based off of the existing ayu theme and is, currently, still a work in progress.
I have only created the mirage color scheme with plans to add dark and light variants at a later time.
Clone or download the theme, and copy ayu.vim to ~/.vim/bundle/lightline.vim/autoload/lightline/colorscheme.
Apply the theme in your .vimrc by adding -- or editing -- the following,
let g:lightline = {
\ 'colorscheme': 'ayu',
\ }