Styled Selector with just CSS

style.css

// CSS

div.select {
    position: relative;
    display: block;
    width: 100%;
    margin-bottom: 1rem;
    border: 1px solid lightgrey;
    border-radius: 10px;
}
div.select select {
    background: transparent;
    color: #2e302d;
    display: inline-block;
    position: relative;
    padding: 8px 30px 6px 10px;
    border: 0;
    border-radius: 0;
    -webkit-appearance: none;
    width: calc( 100% );
    z-index: 1;
    font-size: 16px;
    margin-right: 0px !important;
    line-height: 1em !important;
}
div.select:after {
    content: '\25BC';
    color: lightgrey;
    background: transparent;
    display: block;
    position: absolute;
    width: 30px;
    height: calc( 100% - 22px );
    top: 0px;
    right: 0px;
    padding: 10px 0px 0px 0px;
    z-index: 0;
    text-align: center;
    font-size: 10px;
}

// HTML

  <div class="style-select">
    <select name="model" id="model">'.$select_html.'</select>     
  </div>