.searchbox {
  margin-bottom: 20px; 
  position:relative; 
  display:inline-block;
}
.searchbox .textbox {
  width: 400px;
  height: 30px;
}
.searchbox-btn {
  white-space: nowrap; 
  margin-top: 3px; position: 
  absolute;
  top: 0;
  left: 370px;
  font-size: 1.14286rem;
}
.searchbox-btn > a {
  text-decoration: none;
}

@media screen and (max-width: 767px) {
 .searchbox{
    display: block;
 }
 .searchbox .textbox {
    width: 100%;
 }
 .searchbox-btn {
   left: 93%
 }
}