您的第一个表单

<form action="/my-handling-form-page" method="post">…</form>

<form action="/my-handling-form-page" method="post">
  <ul>
    <li>
      <label for="name">Name:</label>
      <input type="text" id="name" name="user_name" />
    </li>
    <li>
      <label for="mail">Email:</label>
      <input type="email" id="mail" name="user_email" />
    </li>
    <li>
      <label for="msg">Message:</label>
      <textarea id="msg" name="user_message"></textarea>
    </li>
  </ul>
</form>

<input type="text" value="by default this element is filled with this text" />

<textarea>
by default this element is filled with this text
</textarea>

<li class="button">
  <button type="submit">Send your message</button>
</li>

<style>
  …
</style>

body {
  /* Center the form on the page */
  text-align: center;
}

form {
  display: inline-block;
  /* Form outline */
  padding: 1em;
  border: 1px solid #ccc;
  border-radius: 1em;
}

ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

form li + li {
  margin-top: 1em;
}

label {
  /* Uniform size & alignment */
  display: inline-block;
  min-width: 90px;
  text-align: right;
}

input,
textarea {
  /* To make sure that all text fields have the same font settings
     By default, textareas have a monospace font */
  font: 1em sans-serif;
  /* Uniform text field size */
  width: 300px;
  box-sizing: border-box;
  /* Match form field borders */
  border: 1px solid #999;
}

input:focus,
textarea:focus {
  /* Additional highlight for focused elements */
  border-color: #000;
}

textarea {
  /* Align multiline text fields with their labels */
  vertical-align: top;
  /* Provide space to type some text */
  height: 5em;
}

.button {
  /* Align buttons with the text fields */
  padding-left: 90px; /* same size as the label elements */
}

button {
  /* This extra margin represent roughly the same space as the space
     between the labels and their text fields */
  margin-left: 0.5em;
}

<form action="/my-handling-form-page" method="post">
  <ul>
    <li>
      <label for="name">Name:</label>
      <input type="text" id="name" name="user_name" />
    </li>
    <li>
      <label for="mail">Email:</label>
      <input type="email" id="mail" name="user_email" />
    </li>
    <li>
      <label for="msg">Message:</label>
      <textarea id="msg" name="user_message"></textarea>
    </li>

    …
  </ul>
</form>

<form action="/my-handling-form-page" method="post">
  <div>
    <label for="name">Name:</label>
    <input type="text" id="name" name="user_name" />
  </div>

  <div>
    <label for="mail">Email:</label>
    <input type="email" id="mail" name="user_email" />
  </div>

  <div>
    <label for="msg">Message:</label>
    <textarea id="msg" name="user_message"></textarea>
  </div>

  <div class="button">
    <button type="submit">Send your message</button>
  </div>
</form>

form {
  /* Just to center the form on the page */
  margin: 0 auto;
  width: 400px;

  /* To see the limits of the form */
  padding: 1em;
  border: 1px solid #ccc;
  border-radius: 1em;
}

div + div {
  margin-top: 1em;
}

label {
  /* To make sure that all label have the same size and are properly align */
  display: inline-block;
  width: 90px;
  text-align: right;
}

input,
textarea {
  /* To make sure that all text field have the same font settings
     By default, textarea are set with a monospace font */
  font: 1em sans-serif;

  /* To give the same size to all text field */
  width: 300px;

  -moz-box-sizing: border-box;
  box-sizing: border-box;

  /* To harmonize the look & feel of text field border */
  border: 1px solid #999;
}

input:focus,
textarea:focus {
  /* To give a little highlight on active elements */
  border-color: #000;
}

textarea {
  /* To properly align multiline text field with their label */
  vertical-align: top;

  /* To give enough room to type some text */
  height: 5em;

  /* To allow users to resize any textarea vertically
     It works only on Chrome, Firefox and Safari */
  resize: vertical;
}

.button {
  /* To position the buttons to the same position of the text fields */
  padding-left: 90px; /* same size as the label elements */
}

button {
  /* This extra margin represent the same space as the space between
     the labels and their text fields */
  margin-left: 0.5em;
}