Dynamically set CSS class from Eval in Repeater Items in ASP.Net

Hello,

I want to use masonry in repeater but I couldn't.

How can I get a random css class in the repeater?

For example let the css code of a line come as qrt-masonry-grid-item-h-x-2 and the bottom line is qrt-masonry-grid-item-h-x-100.

I want to add a random class this way how can I do?

My masonry css class

qrt-masonry-grid-item-h-x-2 
and 
rt-masonry-grid-item-50

My Repeater 

                        <asp:Repeater ID="rptDetaylar" runat="server">
                            <ItemTemplate>
                                <div class="qrt-masonry-grid-item <%#Eval ("KatID") %> interior">
                                    <div class="qrt-work-item">
                                        <a data-fancybox="works" href="/Fotolar/ProjeDetay/<%#Eval ("KapakFoto") %>" class="qrt-cursor-scale qrt-work-cover-frame">
                                            <img src="/Fotolar/ProjeDetay/<%#Eval ("KapakFoto") %>" alt="work cover">
                                            <div class="qrt-item-zoom qrt-cursor-color"><i class="fas fa-expand"></i></div>
                                            <div class="qrt-work-category"><span><%#Eval ("ProjeAdi") %></span><span>(<%#Eval ("KatAdi") %>)</span></div>
                                        </a>
                                        <div class="qrt-work-descr">
                                            <h4 class="qrt-cursor-color qrt-white">
                                                <a href='/<%# String.Format("ProjeDetay/{0}/{1}",Eval("ProjeID").ToString(),Seo.Temizle(Eval("ProjeAdi").ToString().ToLower())) %>'><%#Eval("ProjeAdi") %></a>
                                            </h4>
                                            <a class="qrt-cursor-scale qrt-work-more qrt-anima-link" href='/<%# String.Format("ProjeDetay/{0}/{1}",Eval("ProjeID").ToString(),Seo.Temizle(Eval("ProjeAdi").ToString().ToLower())) %>'><i class="fas fa-arrow-right"></i></a>
                                        </div>
                                    </div>
                                </div>
                            </ItemTemplate>
                        </asp:Repeater>

in this line normaly theme masonry class

This my div 

<div class="qrt-masonry-grid-item <%#Eval ("KatID") %> interior">

This Thema Div 

<div class="qrt-masonry-grid-item rt-masonry-grid-item-50 interior">

My Repeater Code Behind 

void ProjeDetaylar()
{
    DataTable dtHaberler = klas.GetDataTable("SELECT 	ProjeDetay.ProjeID, 	ProjeDetay.KatID, 	ProjeDetay.ProjeAdi, 	ProjeDetay.Aciklama, 	ProjeDetay.KapakFoto, 	ProjeDetay.BaslangicTarihi, 	ProjeDetay.BitisTarihi, 	ProjeDetay.ArkaPlanGorsel, 	ProjeDetay.SeoBaslik, 	ProjeDetay.SeoKelime, 	ProjeDetay.SeoAciklama, 	ProjeKat.KatID, 	ProjeKat.KatAdi FROM	ProjeDetay	INNER JOIN	dbo.ProjeKat	ON 		ProjeDetay.KatID = ProjeKat.KatID ORDER BY	ProjeDetay.ProjeAdi ASC");
    rptDetaylar.DataSource = dtHaberler;
    rptDetaylar.DataBind();
}

Thanks for help