Q:

additional space between css classes in html markup

what is the difference between this
<p class="class1 class2"></p>

and this
<p class="class1  class2"></p>

the second has an extra space between the classes. both are working fine.
but, will it create any problem while working with javascript or jquery etc?

A:

Having spaces in classes like that should never make a difference, for the exception that some HTML validator might get picky about it. Naturally though, you should try to avoid it.

A:

HTML accepts one space only and converts more than one space to one space. So when you write:

<p class="class1 class2"></p>

it's equal to:
<p class="class1   class2"></p>

Note:However better way is use one space. 

.c1.c2 {
    width: 350px;
    height: 100px;
    background-color: red;
    margin: 10px;
}
<div class="c1               c2">I have more than one space.(We have same style)</div>
<div class="c1 c2">I have one space.(We have same style)</div>

