[CSS] user-select: none 의 사용범위

https://ux.stackexchange.com/questions/83184/is-user-select-none-bad-ux/83249

https://www.webpagefx.com/blog/web-design/disable-text-selection/

https://blogs.msdn.microsoft.com/ie_ko/2012/01/18/css-user-select/

https://css-tricks.com/almanac/properties/u/user-select/

http://caniuse.com/#search=user-select