A Pen by Andy Walpole.

index.html

 <!--[if gte IE 9]><label for="favcity" class="ie9"><![endif]-->
   <!--[if !IE]><!--><label for="favcity"><!--<![endif]-->
    <select id="favcity" name="select">
      <option value="0">Choose your favorite city</option>
      <option value="1">Amsterdam</option>
      <option value="2">Buenos Aires</option>
      <option value="3">Delhi</option>
      <option value="4">Hong Kong</option>
      <option value="5">London</option>
    </select>
  </label>

style.css

body {
  padding: 20px;
  color: #373737;
  font-size: 62.5%;
  line-height: 2.0em;
}

*, *:before, *:after {
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}

select {
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  border-radius: 0;
}

label[for=favcity] {
  position: relative;
  display: block;
  width: 400px;
  overflow: hidden;
  cursor: pointer;
}

label[for=favcity]::after {
  content: ' ';
  position: absolute;
  right: 0;
  top: 0;
  width: 40px;
  height: 100%;
  display: block;
  background: #24d7ea url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAOBAMAAAGq7RFVAAAAJ1BMVEX///////////////////////////////////////////////////9Ruv0SAAAADHRSTlMACAoREoKDt7y9zc5qtZoyAAAAcklEQVQIHQXBsQnCUAAFwFOCCKbIABaWERzi1yaFAzmEpHYEC8GUKVQEkbyhvOOkZqdWt0/QYKqLzQeF7dv6y/RLwa2wYtk4Xxxe+t8yd1WuM/rcUc2gYHEeoP02umSgTR50ybBPRuiSZAS6ZAQ4jgCAPyjYJiRH4fymAAAAAElFTkSuQmCC') no-repeat center center;
  pointer-events: none;
}

label[for=favcity] select {
  border: 5px solid #eeeeee;
  background: white;
  padding: 7px 20px 7px 20px;
  width: 100%;
  font-size: 16px;
  font-family: monospace;
  cursor: pointer;
}

label[for=favcity] :-moz-any(select) {
  width: 110%;
}

label[for=favcity] select::-ms-expand {
    display: none;
}

label[for=favcity].ie9 select {
  width: 110%;
}

label[for=favcity] select:focus {
  outline: 1px dotted #A9A9A9;
}

Styling-a-dropdown-select-list.markdown

Styling a dropdown select list

A Pen by Andy Walpole on CodePen.

License.