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

body {
    margin: 0;
    height: 100vh;
    background-color: darkgrey;
    display: flex;
    align-items: center;
    justify-content: center;
  }

select, #amount {
  padding: 10px;
  margin: 20px;
  min-width: 300px;
}

#rateNow, #result{
  padding: 10px;
  width: 100px;
  background-color: antiquewhite;
  margin: 10px;
}