Icon social, menu links problems

Hello,

I would like to chance a social icon in css with :

#top .social_bookmarks li:hover a {
background: transparent !important;
}
#top .social_bookmarks li a:before{
content: “” !important;
display: block !important;
width: 30px !important;
height: 30px !important;

}
#top .social_bookmarks li.social_bookmarks_instagram a:before {
background: url(../myiconofinstagram.jpg) repeat center center;background-size:30px 30px !important;
}

Without success, impossible to show my icon (PNG)…

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Second problem, with burger menu.

I would like every links are black #000 but on hover, the black is more clear… even if :

#av-burger-menu-ul li a:active .avia-menu-text,#av-burger-menu-ul li a:hover .avia-menu-text,#av-burger-menu-ul li a{color:#000 !important}

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Thanks you for your help.