var jetzt = new Date();
var Monat = jetzt.getMonth();

if (Monat == 0) document.logo1.src = "bilder/winter.jpg";
if (Monat == 1) document.logo1.src = "bilder/winter.jpg";
if (Monat == 2) document.logo1.src = "bilder/fruehling.jpg";
if (Monat == 3) document.logo1.src = "bilder/fruehling.jpg";
if (Monat == 4) document.logo1.src = "bilder/fruehling.jpg";
if (Monat == 5) document.logo1.src = "bilder/sommer.jpg";
if (Monat == 6) document.logo1.src = "bilder/sommer.jpg";
if (Monat == 7) document.logo1.src = "bilder/sommer.jpg";
if (Monat == 8) document.logo1.src = "bilder/sommer.jpg";
if (Monat == 9) document.logo1.src = "bilder/herbstbaum.jpg";
if (Monat == 10) document.logo1.src = "bilder/herbstbaum.jpg";
if (Monat == 11) document.logo1.src = "bilder/winter.jpg";
if (Monat == 12) document.logo1.src = "bilder/winter.jpg";