Try this (demo):
.ui-autocomplete {
position: absolute;
top: 100%;
left: 0;
z-index: 1000;
display: none;
float: left;
min-width: 160px;
padding: 5px 0;
margin: 2px 0 0;
list-style: none;
font-size: 14px;
text-align: left;
background-color: #ffffff;
border: 1px solid #cccccc;
border: 1px solid rgba(0, 0, 0, 0.15);
border-radius: 4px;
-webkit-box-shadow: 0 6px 12px rgba(0, 0, 0, 0.175);
box-shadow: 0 6px 12px rgba(0, 0, 0, 0.175);
background-clip: padding-box;
}
.ui-autocomplete > li > div {
display: block;
padding: 3px 20px;
clear: both;
font-weight: normal;
line-height: 1.42857143;
color: #333333;
white-space: nowrap;
}
.ui-state-hover,
.ui-state-active,
.ui-state-focus {
text-decoration: none;
color: #262626;
background-color: #f5f5f5;
cursor: pointer;
}
.ui-helper-hidden-accessible {
border: 0;
clip: rect(0 0 0 0);
height: 1px;
margin: -1px;
overflow: hidden;
padding: 0;
position: absolute;
width: 1px;
}