Here is my form code:
<td align="center" style=" width=50%; height=50%; background: url(images/side.gif) repeat-x ;">
<img src="images/iphone.gif" width="670" height="549" alt="">
<img style="position:fixed; left:280px; bottom:50px;"src="spr2.png" width="2%" height="15%" alt="">
<form style="display:inline-block;" method="POST" action="index.php">
<label style="position:fixed; left: 200px; bottom: 130px;">: اسم المستخدم</label>
<input style="position:fixed; left:50px; bottom:130px;" type="text" name="username" size="20"><br>
<label style="position:fixed; left:200px; bottom:100px;">: كلمة المرور</label>
<input style="position:fixed; left:50px; bottom:100px;" type="password" name="password" size="20"><br>
<input style="position:fixed; left:50px; bottom:60px;" type="submit" value=" تسجيل دخول ">
</form>
</td>
Here are screen shots from different browsers:

The elements change position when I resize the window:

How can I prevent the elements from changing position and width?
For the width issue, try utilizing the
width, like in this JSFiddle.Your problem with
positionmight stem from the fact that you’re using the value offixed. Absolute positioning inside of relative positioning might be more like what you’re going for.