ourDate = new Date();

var time = ourDate.getHours();

//daca e zi, arata stylesheet de zi
if (time > 7 && time < 19)
{
    document.write('<link href="http://www.tabereski.ro/css/style.css" rel="stylesheet" type="text/css" media="screen" />');
}
//altfel, arata-l pe cel de noapte
else
{
   document.write('<link href="http://www.tabereski.ro/css/style-noaptea.css" rel="stylesheet" type="text/css" media="screen" />'); 
}