Code
<html>
<head>
<meta http-equiv="Content-Language" content="ru">
<meta http-equiv="Content-Type" content="text/html; charset=windows-1251">
<title>http://isofter.ucoz.com/</title>
<Script Language="JavaScript">
var computed = false
var decimal = 0
function convert (entryform, from, to)
{convertfrom = from.selectedIndex
convertto = to.selectedIndex
entryform.display.value = (entryform.input.value * from[convertfrom].value / to[convertto].value )}
function addChar (input, character)
{if((character=='.' && decimal=="0") || character!='.')
{(input.value == "" || input.value == "0") ? input.value = character : input.value += character
convert(input.form,input.form.measure1,input.form.measure2)
computed = true
if (character=='.')
{decimal=1}}}
function openVothcom()
{window.open("","Display window","toolbar=no,directories=no,menubar=no");}
function clear (form)
{form.input.value = 0
form.display.value = 0
decimal=0}
function changeBackground(hexNumber)
{document.bgColor=hexNumber}
</Script>
</head>
<body bgColor=#ffffff link="#008000">
<Form Method="POST" Name="background">
<p align="center">
<Input Type="button" Value="yellow" OnClick="changeBackground('#fff000')">
<Input Type="button" Value="black" OnClick="changeBackground('#000000')">
<Input Type="button" Value="white" OnClick="changeBackground('#ffffff')">
<Input Type="button" Value="green" OnClick="changeBackground('#00ff00')">
<Input Type="button" Value="blue" OnClick="changeBackground('#0000ff')">
<Input Type="button" Value="orange" OnClick="changeBackground('#ff8000')">
<Input Type="button" Value="gray" OnClick="changeBackground('#c0c0c0')">
<Input Type="button" Value="red" OnClick="changeBackground('#ff0000')">
</Form>
</body>
</html>
Посмотреть работу скрипта можно здесь: