ControlGroup HUGE Input Text Box, please help...

ControlGroup HUGE Input Text Box, please help...

Hello, I hope everything goes fine with you all!  , I'm sorry to bother you but I have a problem I would like to resolve... 

I would like to do a simple inputbox with a button on the right side... similar to screenshot1 (attached)... but no matter if I copy the html code and the CSS from the jquery mobile page, it produces a HUGE inputbox with a lot of padding... (please check screenshot2)... here's my code... 
  2. <div data-role="controlgroup" data-type="horizontal">
  3.     <select>
  4.         <option>1</option>
  5.     </select>
  6.     <input id="mybox" type="text" data-mini="true" data-wrapper-class="ui-btn" style="">

  8. </div>
I did not include the CSS but the result is the same, it's just huge... 

PLEASE, I would like to understand why this is happening... thank you for your help! :-)