// run when checkbox is clicked to synchronise the delivery details with billing details
function IsDeliverySame_clicked() {

    if (document.stage.deliverysame.checked) {

        document.stage.dfirstname.value = "";
        document.stage.dfirstname.className = "DisabledTextBox";
        document.stage.dfirstname.disabled = true;
        
        document.stage.dsurname.value = "";
        document.stage.dsurname.className = "DisabledTextBox";
        document.stage.dsurname.disabled = true;
        
        document.stage.daddress1.value = "";
        document.stage.daddress1.className = "DisabledTextBox";
        document.stage.daddress1.disabled = true;

        document.stage.daddress2.value = "";
        document.stage.daddress2.className = "DisabledTextBox";
        document.stage.daddress2.disabled = true; 

        document.stage.dtown.value = "";
        document.stage.dtown.className = "DisabledTextBox";
        document.stage.dtown.disabled = true;

        document.stage.dpostcode.value = "";
        document.stage.dpostcode.className = "DisabledTextBox";
        document.stage.dpostcode.disabled = true;

    } 
    else 
    {

        document.stage.dfirstname.value = "";
        document.stage.dfirstname.className = "RequiredTextBox";
        document.stage.dfirstname.disabled = false;
        document.stage.dfirstname.focus();

        document.stage.dsurname.value = "";
        document.stage.dsurname.className = "RequiredTextBox";
        document.stage.dsurname.disabled = false;
        
        document.stage.daddress1.value = "";
        document.stage.daddress1.className = "RequiredTextBox";
        document.stage.daddress1.disabled = false;

        document.stage.daddress2.value = "";
        document.stage.daddress2.className = "NonRequiredTextBox";
        document.stage.daddress2.disabled = false; 

        document.stage.dtown.value = "";
        document.stage.dtown.className = "NonRequiredTextBox";
        document.stage.dtown.disabled = false;

        document.stage.dpostcode.value = "";
        document.stage.dpostcode.className = "RequiredTextBox";
        document.stage.dpostcode.disabled = false;

    }
}