摆脱文本框验证边框

<label for="username">用户名：</label>
<input type="text" id="username" name="username" required>

document.getElementById("username").style.border = "1px solid transparent";

#username {
  border: 1px solid transparent;
}

<form>
  <label for="username">用户名：</label>
  <input type="text" id="username" name="username" required>
</form>

form {
  border: 1px solid #ccc;
  padding: 20px;
}

label {
  display: block;
  margin-bottom: 10px;
}

<form action="/submit" method="post">
  <label for="username">用户名：</label>
  <input type="text" id="username" name="username" required>
  <button type="submit">提交</button>
</form>