.dropdown {
  position: relative;
  z-index: 10;
  display: inline-block;
  -webkit-user-select: none;
  -moz-user-select: none;
  user-select: none;
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}
.dropdown * {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}
.dropdown button {
  border: 1px solid #ccc;
  padding: 5px;
  cursor: pointer;
  background-color: #fff;
  width: 100%;
  text-align: left;
}
.dropdown ul {
  width: 100%;
  position: absolute;
  visibility: hidden;
  overflow: hidden;
  border: 1px solid #ccc;
  border-top: none;
  height: 0;
  background-color: #fff;
  list-style-type: none;
  padding: 0;
  margin: 0;
}
.dropdown ul.open {
  visibility: visible;
  overflow-y: auto;
  height: auto;
}
.dropdown ul li {
  padding: 5px;
  cursor: pointer;
}
.dropdown ul li:hover {
  background-color: #efefef;
}
.dropdown ul li.selected {
  background-color: #efefef;
}
.caret {
  position: absolute;
  top: 12px;
  right: 7px;
  display: inline-block;
  width: 0;
  height: 0;
  margin-left: 2px;
  vertical-align: middle;
  border-top: 5px dashed;
  border-right: 5px solid transparent;
  border-left: 5px solid transparent;
}