Code
<!-- Плавно изменяет цвет заднего фона  
 Copyright © WINsoft 1997-2007-->  
 <script>  
 function initArray()  
 {  
 this.length = initArray.arguments.length  
 for (var i = 0; i < this.length; i++)  
 this[i+1] = initArray.arguments[i]  
 }  
 var hexChars = "0123456789ABCDEF";  
 function Dec2Hex (Dec)  
 {  
 var a = Dec % 16;  
 var b = (Dec - a)/16;  
 hex = "" + hexChars.charAt(b) + hexChars.charAt(a);  
 return hex;  
 }  
 function bgChanger (begin, end, steps)  
 {  
 steps = steps -1 ;  
 redA = begin.charAt(0) + begin.charAt(1);  
 red_valA = parseInt(redA,'16');  
 redB = end.charAt(0) + end.charAt(1);  
 red_valB = parseInt(redB,'16');  
 red_int = ((red_valB - red_valA) / steps) * -1;  
 grnA = begin.charAt(2) + begin.charAt(3);  
 grn_valA = parseInt(grnA,'16');  
 grnB = end.charAt(2) + end.charAt(3);  
 grn_valB = parseInt(grnB,'16');  
 grn_int = ((grn_valB - grn_valA) / steps) * -1;  
 bluA = begin.charAt(4) + begin.charAt(5);  
 blu_valA = parseInt(bluA,'16');  
 bluB = end.charAt(4) + end.charAt(5);  
 blu_valB = parseInt(bluB,'16');  
 blu_int = ((blu_valB - blu_valA) / steps) * -1;  
 step = 2;  
 red = red_valA;  
 grn = grn_valA;  
 blu = blu_valA;  
 document.bgColor = begin;  
 while ( steps >= step )  
 {  
 red -= red_int;  
 red_round = Math.round(red);  
 red_hex = Dec2Hex(red);  
 grn -= grn_int;  
 grn_round = Math.round(grn);  
 grn_hex = Dec2Hex(grn);  
 blu -= blu_int;  
 blu_round = Math.round(blu);  
 blu_hex = Dec2Hex(blu);  
 document.bgColor = red_hex + grn_hex + blu_hex;  
 step++;  
 }  
 document.bgColor = end;  
 }  
 </script>  
 <body bgcolor=#000000 text=#FFFFFF link="FF0000" vlink="8888FF" alink="FF00FF">  
 <script>  
 <!--  
 bgChanger("000000","000000",25);  
 bgChanger("000000","FF0000",25);  
 bgChanger("FF0000","000000",25);  
 bgChanger("000000","AA00EE",25);  
 bgChanger("AA00EE","000000",25);  
 bgChanger("000000","0000FF",25);  
 bgChanger("0000FF","000000",25);  
 bgChanger("000000","000000",25);  
 // -->  
 </script>
Code
bgChanger("AA00EE","000000",25);