.mce-custom-btn-info > button{
    color: #fff!important;
    background-color: #5bc0de;
    border-color: #46b8da;
}
.tox-button[title='Browse Files...']
{
    color: #fff!important;
    background-color: #5bc0de!important;
    border-color: #46b8da!important;
    width:100%;
}