Input stepping down - php

Question

I'm having a step down issue with my registration form, I've tried everything I can find on google but nothing works.
My DOB section is split into 3 different input boxes, I'm trying to get the right column up beside the left but as soon as I put any styling on it, the year section steps down.
I've tried so many different variations; Float, display, nothing works. Also I've added extra boxes and it's always after the first 2 boxes the step down happens.
When I try to style, notice the year step down:
Always steps down after 2 no matter what order:
HTML code:
<div id="regforms">
<form method="post" action="register.php" name="registerform" id="registerform">
<fieldset2>
<div id="regforms1">
<label for="username"></label><input type="text" name="username" id="username" placeholder="Username"/><br />
<label for="password"></label><input type="password" name="password" id="password" placeholder="Password"/><br />
<label for="email"></label><input type="text" name="email" id="email" placeholder="Email"/><br />
<input type="submit" name="register" id="login" value="Register" />
</div>
<div id="regforms2">
<label for="name"></label><input type="text" name="name" id="name" placeholder="Name"/><br />
<div id="dob">
<label for="dobm"><input type="text" name="month" id="month" placeholder="MM"/><br />
<label for="dobd"><input type="text" name="day" id="day" placeholder="DD"/><br />
<label for="dobd"><input type="text" name="day" id="day" placeholder="DD"/><br />
<label for="dobd"><input type="text" name="day" id="day" placeholder="DD"/><br />
<label for="doby"><input type="text" name="year" id="year" placeholder="YYYY"/><br />
</div>
</div>
</fieldset3>
</form>
</div>
CSS:
#regforms {
margin-top:200px;
border: 0;
display:block;
width:600px;
}
#regforms1 {
padding-right:25px;
width:275px;
float:left;
}
#regforms2 {
width:275px;
float:right;
}
#dob {
}
#month{
width:5%;
margin-right:5px;
}
#day{
width:10%;
margin-right:5px;
}
#year{
width:10%;
margin-right:5px;
}

Answer 1

As Aligarian said, you just need to remove the <br/> tag, although you don't seem to be closing the <label> tags in the DOB fields; you should close them.