Can't get browsers to display a div with some justified text at the same width

Below is the CSS style this div is using. The div itself is nested within a table. Basically IE displays this differently from FireFox and Chrome. I like the IE rendering better and it seems more inline with what I am seeing in dreamweaver, where as firefox and chrome will display the div wider then it's in IE and dreamweaver for some reason.

I haven't designed anything in a while but it's sad to see that we still have these rendering differences between browsers, is this still the case with HTML5/CSS3 ?

.Class420 {
    font-family:Arial,Helvetica,sans-serif;
    font-size:14px;
    color:#000;
    line-height:30px;
    background-color:#F5F5F5;
    w开发者_运维问答idth:400px;
    text-align:justify;
    padding:15px;
    float: left;
    margin-left: 15px;
    height: 300px;
}

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is this still the case with HTML5/CSS3 ?

Yes. And it's still Internet Explorer which is holding everyone back.