developer/css/default/social_buttons.css

/* Background colors */
.btn-facebook,.btn-github,.btn-google,.btn-linkedin,.btn-live,.btn-windows,.btn-mailru,.btn-openid,.btn-steam,.btn-twitch,.btn-twitter,.btn-xing,.btn-yandex {
    color: #f9f9f9 !important;
}
.btn-facebook {
    background-color: #3b5998 !important;
}
.btn-github {
    background-color: #6cc644 !important;
}
.btn-google {
    background-color: #dd4b39 !important;
}
.btn-linkedin {
    background-color: #007bb6 !important;
}
.btn-live {
    background-color: #2672ec !important;
}
.btn-windows {
    background-color: #2672ec !important;
}
.btn-mailru {
    background-color: #0857a6 !important;
}
.btn-openid {
    background-color: #f78c40 !important;
}
.btn-steam {
    background-color: #000000 !important;
}
.btn-twitch {
    background-color: #6441a5 !important;
}
.btn-twitter {
    background-color: #2ba9e1 !important;
}
.btn-xing {
    background-color: #006567 !important;
}
.btn-yandex {
    background-color: #ffcc00 !important;
}