Merge remote-tracking branch 'origin/dev'

* origin/dev:
  throw error when css string is invalid
Fix typo in README

raito -> ratio, it was fixed in code but not applied here.
Merge pull request #41 from lqez/master

Fix typo in README
Fix duble quations
Fix utii.functions
Support file contents
Add test
Support parse html page #19
Add error handling
Merge pull request #42 from t32k/support-parse-html

Support parse html page #19
Bump v3.0.0