function color_rechnen() {

var menge = document.forms["color_form"]["menge"].value.replace(',','.');
menge = Math.floor(menge);
if (!menge || menge < 1 || menge > 100) {
	menge = 1;
}
document.forms["color_form"]["menge"].value = menge;

var breite = Math.abs(document.forms["color_form"]["breite"].value.replace(',','.'));
if (!breite || breite < 5) {
	breite = 5;
}
if (breite > 50) {
	breite = 50;
}
document.forms["color_form"]["breite"].value = breite;

var hoehe = 0.5;
var preis = document.forms["color_form"]["preis"].value;
var epreis = document.forms["color_form"]["epreis"].value;
var summa = document.forms["color_form"]["summa"].value;

preis = 7.5;
epreis = 0;
summa = 0;


epreis = Math.round(breite * hoehe * preis * 100) / 100;
summa = Math.ceil(menge * breite * hoehe * preis * 100) / 100;

document.forms["color_form"]["epreis"].value = epreis.toFixed(2)+' €';

document.forms["color_form"]["summa"].value = summa.toFixed(2)+' €';

// alert(epreis);
}