След като тобавихте това в индекса не забравяйте и да добавите този код на custom.css попринцип който ще да бъде

.social_icons{
left: 0; margin: 16% auto auto 10px; position: fixed;
}

.social_icons img{
    opacity: 0.5;
    filter: alpha(opacity=50);
    -webkit-transition: all 1s ease-in-out;
    -webkit-transform: rotate(-360deg);
    -moz-transition: all 1s ease-in-out;
    -o-transition: all 1s ease-in-out;
    -ms-transition: all 1s ease-in-out;
}

.social_icons img:hover{
	padding: 7px;
    opacity: 100;
    filter: alpha(opacity=40);
    -moz-transition: all 0.5s ease-out;
    -o-transition: all 0.5s ease-out;
    -webkit-transition: all 05s2s ease-out;
    -ms-transition: all 0.5s ease-out;
    transition: all 0.5s ease-out;
    -webkit-transform: rotate(360deg);
    -moz-transform: rotate(360deg);
    -o-transform: rotate(360deg);
    -ms-transform: rotate(360deg);
}