With the DOCTYPE you are using you should close certain tags with />
<link href="mycss.css" rel="stylesheet" type="text/css" />
This includes input tags, and <br> should be <br /> - or switch to HTML5
It is preferable to use a submit button, rather than an input-button:
<input type="submit" name="btnSubmit" id="btnSubmit" value="Submit" />
Your formSubmit() function should be called in the onsubmit event of the form, otherwise it will not be called if someone just presses Enter:
<form action="step2.php" method="get" id="login" onsubmit="formSubmit();">
Your formSubmit() code needs to return false;
if you wish to prevent the form-submission.
You should ideally test against '5' rather than the number 5, as form-values are strings:
if ( document.getElementById("pass").value == '5' )
BTW I would prefer not to use the variable name 'node', but that's just me!