.footer-tab-item {
    width: 28px;
    height: 24px; 
    background-size: contain; 
    background-repeat: no-repeat;
}
.middle-content {
    background-size: contain; 
    background-repeat: no-repeat;
}
.middle-content-contacts {
    background-image: url('../images/app-preview/contacts.png');
}
.middle-content-message {
    background-image: url('../images/app-preview/message.png');
}
.middle-content-workbench {
    background-image: url('../images/app-preview/workbench.png');
}
.middle-content-alert {
    background-image: url('../images/app-preview/alert.png');
}
.middle-content-me {
    background-image: url('../images/app-preview/me.png');
}