Rule Display by Validator

==============
QUESTION
==============

Why did the CSS Validator alter this rule:

FROM -> background: rgb(75%,85%,70%);

TO -> background : rgb(75.0,85.0,70.0);

Note that each of the percent values appear as decimal numbers. For 
example, 75% appears as 75.0. However,  I used a percent -- not a 
number between 0 and 255.

Why were the percents changed to numbers?


==============
WHAT I DID
==============

I pasted the following snippet into the box labeled "VALIDATE BY DIRECT 
INPUT", as follows:

.panel  {
 background: rgb(75%,85%,70%);
}

After clicking CHECK, the Validator  reported "No error or warning 
found", and displayed the rule under the caption "Valid CSS 
Information", as follows:

•  .panel  {
 ◦  background : rgb(75.0,85.0,70.0);
}

Oddly,  Validator is not displaying the same rule I entered in the 
"VALIDATE BY DIRECT INPUT" box.

The link for the CSS Validator I used is:
http://jigsaw.w3.org/css-validator/