lg:hidden not working with flex

[MZOG]

trafficstars

Hi, I just downloaded theme and started to implement my own header. So I have <div class="flex lg:hidden"> and it should be hidden on lg screen but it's not.

Also I don't know why there is !important added to the flex property.

I've searched all files for any !important but there is none. I'm a bit confused why it's not working.