So a bit of an odd-ball one here, and not sure the title is perfectly correct. I've set up a bare-bones sample repo that is showing this issue as well as put it up on Netlify.
Element-UI is a UI toolkit for Vue 2, and I'm seeing some very odd behaviour when using within a Nuxtjs project. I think it's Nuxtjs specific issue (used components within other apps fine) but if you think otherwise I'll also open a ticket over in their repo too!
The GIF show's it best, but as you can see when I open the date picker, the head goes through a number of weird changes (title changes, meta tags disappear) and never resets itself. Are they doing something weird or is Nuxtjs not handling the DOM changes they do?
GIF recording Sample repo Sample website
Nuxtjs: 0.10.6 (latest from vue init nuxt/starter)
Node: 6.10.2/7.10.0
ElementUI: 1.2.9
Browser/OS: MacOS 10.11+ on Chrome 56+ and Safari 10, Windows 10 on Chrome 56+, Mobile Safari on iOS 10.3