How to remove vertical padding from the <button> in Safari on iPhone?

button {
background:pink;
border:none;
border-radius:5px;
color:black;
cursor:pointer;
font-size:150%;
margin:0;
padding:0;
position:relative;
top:30%;
text-shadow:0 0 1px white;
overflow:visible;
-webkit-appearance:none;
-webkit-box-shadow:0 1px 3px rgba(0, 0, 0, 0.5);
}