After YCM was installed, no other configuration was added to. vimrc.
JavaScript can be completed automatically now (for example, if you enter Obj, a popup will automatically appear to let you select the required completion), but css needs to be completed by omnicomplete according to [c-x] [c-o]. how can css files be completed automatically like JavaScript?
Put this code in your. vimrc and change the number 4 to your indent setting.
let g:ycm_semantic_triggers = { \ 'css': [ 're! ^\s{4}', 're! :\s+' ], \ }
Reference link:YCM will not use omnicompletion results in .css files · Issue #413 · Valloric/YouCompleteMe