// Detectar navegador
browser_name = navigator.appName;
browser_version = parseFloat(navigator.appVersion); 

if (browser_name == "Netscape" && browser_version >= 3.0) { roll = 'true'; }
else if (browser_name == "Microsoft Internet Explorer" && browser_version >= 4.0) { roll = 'true'; }
else { roll = 'false'; }

// Precarga de imágenes si el navegador soporta mouseovers
if (roll == 'true') {

var imglist = new Array (
"/img/imgalcantarillado.jpg",
"/img/imgalcantarillado2.jpg",
"/img/imggalerias.jpg",
"/img/imggalerias2.jpg",
"/img/imgmobiliario.jpg",
"/img/imgmobiliario2.jpg",
"/img/imgjardineria.jpg",
"/img/imgjardineria2.jpg",
"/img/imgpavimentos.jpg",
"/img/imgpavimentos2.jpg",
"/img/imgedificacion.jpg",
"/img/imgedificacion2.jpg",
"/img/imgaparcamientos.jpg",
"/img/imgaparcamientos2.jpg",
"/img/imgmedioambiente.jpg",
"/img/imgmedioambiente2.jpg",
"/img/imglimpieza.jpg",
"/img/imglimpieza2.jpg",
"/img/imgmantenimiento.jpg",
"/img/imgmantenimiento2.jpg",
"/img/imgviaria.jpg",
"/img/imgviaria2.jpg",
"/img/redes.jpg",
"/img/redes2.jpg"
);
var imgs = new Array();

var count;
if (document.images)
for (count=0; count<imglist.length; count++)
{imgs[count]=new Image(); imgs[count].src=imglist[count];}
}

function msover2(img1,ref1,img2,ref2) { if (roll == 'true') 
{ document.images[img1].src = ref1; document.images[img2].src = ref2} }
function msout2(img1,ref1,img2,ref2) { if (roll == 'true') 
{ document.images[img1].src = ref1; document.images[img2].src = ref2} }