CSS style as color attribute on font tags

Question 1

style="color:rgb(255,255,0)". The font tag is deprecated and inline style should also be avoided. Don't forget your double quotes on attribute names: attr="value" not attr=value

This would be best done in CSS using a target class:

<p class="my-class">Some text</p>

In your css file:

.my-class {
  color: rgb(255,255,0);
}

The
tag is also not to be used for layout. It should only be used for new-lines in text. Instead, use display: block on the elements that should be on a new line.

Here's a complete sample: (note that <p> tags have display: block by default)

<p class="red-text">Red</p>
<p class="green-text">Green</p>
<p class="gold-text">Gold</p>

CSS:

.red-text {
  color: #FF0000; 
}

.green-text {
  color: green; 
}

.gold-text {
  color: rgb(255,255,0);
}

Live demo (click).

Question 2

How about this?

 <style>
   .red{
       color: #FF0000;
  }
</style>

HTML Tag:

 <div class="red" >Red</div>

Question 3

<html>
<head>
<title>webpage name</title>
</head>
<body>
<font color="#FF0000">Red</font> (it's look right).
<BR>
<font color=green>Green</font>(wrong).
<BR>
<font color= rgb(255,255,0)>Gold</font>(wrong).
</body>
</html>

modified

<html>
<head>
<title>webpage name</title>
</head>
<body>
<font color="#FF0000">Red</font>
<BR>
<font color="green">Green</font>
<BR>
<font color="rgb(255,255,0)">Gold</font>
</body>
</html>