como disse, kando carrega, usa o css normal,
e como disse dinvo, voces terias que implementar ele
mais ta ai o css do nivo que aparece no site de todos
Código: Selecionar todos#slider{position:relative;min-height:220px;background:#202834 url(http://nivo.dev7studios.com/images/loading.gif) no-repeat 50% 50%;margin:0px 0px 50px;}
#slider img{position:absolute;top:0;left:0;display:none;}
#slider a{border:0;display:block;}
.nivo-controlNav{position:absolute;left:47%;bottom:-30px;}
.nivo-controlNav a{display:block;width:10px;height:10px;background:url(http://nivo.dev7studios.com/images/bullets.png) no-repeat;text-indent:-9999px;border:0;margin-right:3px;float:left;position:relative;z-index:99;cursor:pointer;}
.nivo-controlNav a.active{background-position:-10px 0;font-weight:700;}
.nivo-directionNav a{display:block;width:30px;height:30px;background:url(http://nivo.dev7studios.com/images/arrows.png) no-repeat;text-indent:-9999px;border:0;position:absolute;top:45%;z-index:99;cursor:pointer;}
a.nivo-nextNav{background-position:-30px 0;right:15px;}
a.nivo-prevNav{left:15px;}
.nivo-caption a{text-decoration:underline;display:inline !important;}
.nivoSlider{position:relative;}
.nivoSlider img{position:absolute;top:0;left:0;}
.nivoSlider a.nivo-imageLink{position:absolute;top:0;left:0;width:100%;height:100%;border:0;z-index:60;display:none;margin:0;padding:0;}
.nivo-slice{display:block;position:absolute;z-index:50;height:100%;}
.nivo-caption{position:absolute;left:0;bottom:0;background:#000;color:#fff;opacity:0.8px;width:100%;z-index:89;}
.nivo-caption p{margin:0;padding:5px;}
.nivo-html-caption{display:none;}
.nivo-prevNav{left:0;}
.nivo-nextNav{right:0;}
soh substituir tudo o css do css que vem no nivo quando baixa