input[type="text"],
      input[type="email"],
      input[type="tel"],
      textarea, fieldset {
        width : 100%;
        border: 1px solid #333;
        box-sizing: border-box;
      }

      input:invalid {
        box-shadow: 0 0 5px 1px red;
      }

      input:focus:invalid {
        box-shadow: none;
      }