fix(_sass/_base.scss): use 18pt for list item (instead of 16pt)
fix(_sass/_base.scss): use 18pt for list item (instead of 16pt)

avigad/leanprover.github.io,leanprover/leanprover.github.io,fpvandoorn/leanprover.github.io,soonhokong/leanprover.github.io,fpvandoorn/leanprover.github.io,leanprover/leanprover.github.io,soonhokong/leanprover.github.io,avigad/leanprover.github.io,fpvandoorn/leanprover.github.io,leanprover/leanprover.github.io,soonhokong/leanprover.github.io,avigad/leanprover.github.io