Hide sidebar and widget in mobile view

Hi there,

I am working on a website http://themes.momizat.com/?theme=goodnews and the theme author said that they have not yet provided an option to hide the widget or sidebar in mobile or responsive view; I tried my level best to hide it in mobile view with the help of CSS by using the following code but it didn’t work, can anyone help me out on this?

@media screen and (max-width: 599px) {
#momizatposts-2 #momizatsocialcounter-2 #momizatnewsletter-2 {
display: none;
}
}