JSFiddle - React, Tailwind, and code Playground

by twobomb three

HTML

<b>Mobile Phone</b>
<div id="customInput">
  <select>
    <option>+31</option>
    <option>+32</option>
    <option>+33</option>
  </select>
  <input type="text">
</div>

CSS

body{
  
  color:#555;
}
#customInput select{
  background:transparent;
  height:40px;
  float:left;
  border-radius:5px;
  color:#555;
  border:2px solid #AAA;
  padding:5px;
}
input {
  color:#555;
  background:transparent;
  box-sizing:border-box;
  margin-left:5px;
  border-radius:5px;
  border:2px solid #AAA;
  padding:0 5px;
  height:40px;
  float:left;
}