Is it possible to use 2 or more classes in html text box or

Question

Hi,
I have a CSS classes named
class1
{
color:red;
}
class2
{
color:blue;
}
class3
{
color:yellow;
}
and I have a text box
<input type="text" id="txtname" class="class1 class2 class3" >

The text box includes 3 classes. So on running the text box which will be the color of the text and how can I predict the color.