$(function() {
          
        var viewportwidth = $(document).width();
        var viewportheight = $(document).height();
        var viewporthalfw = Math.round($(document).width()/2);
        var windowwidth = $(window).width();
        var windowheight = $(window).height();  

        /* main navigation
        ******************************/
        switch (window.location.pathname){
           case "/index.php":
              $("#main-nav #index").addClass("current");
              break;
           case "/novinky.php":
              $("#main-nav #novinky").addClass("current");
              break;
           case "/projekty.php":
              $("#main-nav #galerie").addClass("current");
              break;
           case "/vystava.php":
              $("#main-nav #vystava").addClass("current");
              break;
           case "/konfrontace.php":
              $("#main-nav #konfrontace").addClass("current");
              break;
           case "/autori.php":
              $("#main-nav #autori").addClass("current");
              break;
           case "/tiskem.php":
              $("#main-nav #tiskem").addClass("current");
              break;
           case "/naklad.php":
              $("#main-nav #naklad").addClass("current");
              break;
        }
        
        /* picture preview
        **************************/

        $("a .obraz").click(function(){           
           $("#preview-shade").css("height",viewportheight).css("width",viewportwidth).show();
           
           //ziskaj orig. rozmery obrazu
           var image = new Image();
           image.src = $(this).attr("src");
           var imH = image.height;
           var imW = image.width;
           
           //napasuj obrazok tak aby nebol vacsi ako sirka okna
           if (imW > windowwidth - 100){
              var ratio = imH / imW;
              imW = windowwidth - 100;
              imH = Math.round(imW * ratio);
           }
           //aby nebol vyssi ako vyska okna
           if (imH > windowheight - 40){
              var ratio = imH / imW;
              imH = windowheight - 40;
              imW = Math.round(imH / ratio);
           }

           var imagehalfw = Math.round(imW/2);
           var imagehalfh = Math.round(imH/2);

           $("#preview-window").css("left",viewporthalfw-imagehalfw).css("top",document.body.scrollTop+10).show();
           $("#preview-window").html('<img src="'+image.src+'" width="'+imW+'" height="'+imH+'">');
           return false;
        });

        $("#preview-shade").click(function(){
           $(this).hide();
           $("#preview-window").hide();
        });
        
        $("#preview-window").click(function(){
           $(this).hide();
           $("#preview-shade").hide();
        });

        /* text slider
        **********************/
        $("#slider").addClass("slider");
        $("#slide").show();
        $("#slide").click(function(){
           $("#slide").hide();
           $("#hide").show();
           $("#slider").slideDown("normal");
           return false;
        });
        $("#hide").click(function(){
           $("#hide").hide();
           $("#slide").show();
           $("#slider").slideUp("normal");
           return false;
        });

     });