To have your desired visual effect you need to figure out to center the form and get the labels to show above the inputs.
#container{
text-align: center;
}
/* FORMS */
#my_form {
display: inline-block;
text-align: left;
line-height: 1.5;
}
#my_form label {
display: block;
}
#my_form input {
margin: 0.25em 0 0.5em;
}
http://fiddle.jshell.net/g4yzZ/13/
http://fiddle.jshell.net/g4yzZ/13/show