i tested this problem in ios7 and 8, the dropdown menu always display all the item (please see the attached file).
Hope you can fix this asap. Thanks.

+1

I've not an iPhone to debug the problem, I'm open to PR from you guys :)

It happens on Safari (Version 7.1.3 (9537.85.12.18)) on Mac OSX Mavericks also.

Problem lies with dropdownjs. Needs to use long-form CSS3 transform scale definition in the CSS file (and possibly for transition and transform-origin). Will add issue on dropdownjs repo. Sample fix below:
(FezVrasta/dropdown.js#11)

.dropdownjs > input.focus ~ ul {
-webkit-transform: scale(1);
-moz-transform: scale(1);
-ms-transform: scale(1);
-o-transform: scale(1);
}
.dropdownjs > ul {
position: absolute;
padding: 0;
margin: 0;
min-width: 200px;
-webkit-transform: scale(0);
-moz-transform: scale(0);
-ms-transform: scale(0);
-o-transform: scale(0);
z-index: 10000;
}

continue here
FezVrasta/dropdown.js#11