Add padding and remove the height. For example here is an update of the code you have supplied:
display: block;
margin-left: 10%;
margin-right: 10%;
margin-top: 10px;
padding-top: 10px;
padding-right: 20px;
padding-bottom: 10px;
padding-left: 20px;
UPDATE
Unfortunately padding may not work in Safari (iPhone). In this case try using text indent instead of padding. And add the text indent of the width of your drop down menu. Please see an update of the code you provided:
display: block;
height: 60px;
margin-left: 10%;
margin-right: 10%;
margin-top: 10px;
min-height: 60px;
width: 220px; /* width of 200px plus the 20px for the text indent */
text-indent: 20px;