1. Place the following on your Page

<style type="text/css">
    .pager
    {
        background-color: #3AC0F2;
        color: white;
        height: 20px;
        min-width: 20px;
        line-height: 20px;
        display: inline-block;
        text-align: center;
        text-decoration: none;
        border: 1px solid #2E99C1;
    }
    .active_pager
    {
        background-color: #2E99C1;
        color: white;
        height: 20px;
        min-width: 20px;
        line-height: 20px;
        display: inline-block;
        text-align: center;
        text-decoration: none;
        border: 1px solid #2E99C1;
    }
</style>

2. Change the Repeater in that article as follows

<asp:Repeater ID="rptPager" runat="server">
    <ItemTemplate>
        <asp:LinkButton ID="lnkPage" runat="server" Text='<%#Eval("Text") %>' CommandArgument='<%# Eval("Value") %>'
            CssClass='<%# Convert.ToBoolean(Eval("Enabled")) == true ? "pager" : "active_pager" %>'
            OnClick="Page_Changed"></asp:LinkButton>
    </ItemTemplate>
</asp:Repeater>