Fix issue filter dropdown conflict with sticky issue header (#1439)
Fix issue filter dropdown conflict with sticky issue header (#1439)

https://user-images.githubusercontent.com/3723666/43109034-b5159d58-8eb2-11e8-9662-06d2626c734b.png
busches/refined-github,sindresorhus/refined-github,sindresorhus/refined-github,busches/refined-github