help me, tha menu is desappeared

hi, i get a problem. I use a child theme in wich i added
#rssfeed { display:none; } to avoid the image of rss feed, ok.
I did a lot of modifyto obtain custom css likely for me. I put the modify of css in tha custom css section in wp backend and I moved it in the styile css of child, but now desappeared the top menu in mobile! what is happenead?? help me please…site psicologaonlinesalerno.it