<form>

  <label for="fname">Họ Và Tên</label>

  <input type="text" id="fname" name="fname">

</form>
input[type=text] {
  width: 100%;
  padding: 12px 20px;
  margin: 8px 0;
  box-sizing: border-box;
  border: 3px solid #ccc;
  -webkit-transition: 0.5s;
  transition: 0.5s;
  outline: none;
}

input[type=text]:focus {
  border: 3px solid #555;
}

External CSS

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External JavaScript

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