我有這些文本字段和搜索按鈕以及一些其他按鈕:

button {
  font-family: Arial Narrow, sans-serif;
  font-size: 20pt;
}

.search {}

.search:after {
  content: "";
  clear: both;
  display: table
}

.search input {
  font-family: Arial Narrow, sans-serif;
  font-size: 20pt;
  width: 160px;
  height: 42px;
  padding-left: 15px;
  border-radius: 42px;
  border: 2px solid #404040;
  background: #FFDFBF;
  outline: none;
  position: relative;
  transition: .3s linear;
}

.search input:focus {
  width: 512px;
}

.search button {
  width: 42px;
  height: 42px;
  background: none;
  border: none;
  position: relative;
  left: -44px;
}

<DIV class="search">
  <INPUT type=text name="q">
  <BUTTON>