Keep open css3 dialog after postback

I have a CSS3 modal dialog with a gridview that will populate when a search is done. However, when I go and actually do a search (and so the postback is called) the modal dialog closes. If I manually open it again, the gridview is populated as I wanted.

My question is how to keep the modal dialog open in code after searching. Any help would be greatly appreciated!

This is my CSS:

    .modalDialog {
        position: fixed;
        font-family: Arial, Helvetica, sans-serif;
        top: 0;
        right: 0;
        bottom: 0;
        left: 0;
        background: rgba(0, 0, 0, 0.8);
        z-index: 99999;
        opacity:0;
        -webkit-transition: opacity 400ms ease-in;
        -moz-transition: opacity 400ms ease-in;
        transition: opacity 400ms ease-in;
        pointer-events: none;
    }

    .modalDialog:target {
        opacity:1;
        pointer-events: auto;
    }

    .modalDialog > div {
        width: 800px;
        position: relative;
        margin: 10% auto;
        padding: 5px 20px 13px 20px;
        /*border-radius: 10px;*/
        background: #fff;
        /*background: -moz-linear-gradient(#fff, #999);
        background: -webkit-linear-gradient(#fff, #999);
        background: -o-linear-gradient(#fff, #999);*/
    }

    .close {
        background: #606061;
        color: #FFFFFF;
        line-height: 25px;
        position: absolute;
        right: -12px;
        text-align: center;
        top: -10px;
        width: 24px;
        text-decoration: none;
        font-weight: bold;
        -webkit-border-radius: 12px;
        -moz-border-radius: 12px;
        border-radius: 12px;
        -moz-box-shadow: 1px 1px 3px #000;
        -webkit-box-shadow: 1px 1px 3px #000;
        box-shadow: 1px 1px 3px #000;
    }

    .close:hover {
        background: #00d9ff;
    }

      

        
        
        
      

    

and HTML:

<a href="#openModal">Open Modal</a>

<div id="openModal" class="modalDialog">
    <div>   
        <a href="#close" title="Close" class="close">X</a>

        <div>
           <asp:Button ID="SearchBtn" runat="server" 
                  OnClick="Search" Text="Search" />
           <asp:GridView ID="gridview" GridLines="None" 
                  AutoGenerateColumns="False" runat="server">
               <Columns>
                   <asp:BoundField SortExpression="Name" DataField="Name"
                        HeaderText="Name" />
               </Columns>
           </asp:GridView>
        </div>
    </div>
</div>