ul[id$=-gf_stla_form_id_my_themes] li.customize-control-button input[id$=_theme_button]{
    background: #0085ba;
    color: #fff;
    cursor:pointer;
    margin-top:15px;
  }
ul[id$=-gf_stla_form_id_my_themes] li.customize-control-button input[id$=_theme_button]:hover {
    background: #008ec2;
    border-color: #006799;
    color: #fff;
  }