.logo-tb-hover, .logo-wmo-hover {
    display: none
    }
.tb_button > a:hover > img.logo-tb-non-hover, .wmo_button > a:hover > img.logo-wmo-non-hover {
    display: none
    }
.tb_button > a:hover > img.logo-tb-hover, .wmo_button > a:hover > img.logo-wmo-hover {
    display: inline
    }