i.mce-i-smiley {
    background: url(../../../wp-includes/images/smilies/simple-smile.png) no-repeat 50% 50%;
    -webkit-background-size: contain;
    background-size: contain;
}

.mce-smily .mce-grid a {
    width: 24px;
    height: 24px;
    padding: 3px;
    text-align: center;
    border: 0;
    -webkit-border-radius: 1px;
    -moz-border-radius: 1px;
    border-radius: 1px;
}

.mce-smily .mce-grid a:hover {
    background: #b4b9be;
}

.mce-smily .mce-grid a img {
    width: auto!important;
    height: auto!important;
    max-width: 100%;
    max-height: 100%;
    vertical-align: middle;
}