:read-write CSS pseudo-class

label,
input[type="submit"] {
  display: block;
  margin-top: 1em;
}

*:read-write {
  background-color: ivory;
  border: 2px solid darkorange;
  border-radius: 5px;
}

<p>Please fill in your details:</p>

<form>
  <label for="email">Email Address:</label>
  <input id="email" name="email" type="email" value="test@example.com">

  <label for="note">Short note about yourself:</label>
  <textarea id="note" name="note">Don't be shy</textarea>

  <label for="pic">Your picture:</label>
  <input id="pic" name="pic" type="file">

  <input type="submit" value="Submit form">
</form>

:read-write {
  /* ... */
}

body {
  font-family: "Josefin Sans", sans-serif;
  margin: 10px auto;
}

legend {
  color: white;
  background: black;
  padding: 5px 10px;
}

fieldset > div {
  margin-bottom: 10px;
  display: flex;
  justify-content: space-between;
}

button,
label,
textarea {
  display: block;
  font-family: inherit;
  font-size: 100%;
  margin: 0;
  box-sizing: border-box;
  padding: 5px;
  height: 30px;
}

textarea {
  width: 50%;
}

textarea {
  height: 70px;
  resize: none;
}

label {
  width: 40%;
}

textarea:read-only {
  border: 0;
}

textarea:read-write {
  box-shadow: inset 1px 1px 3px #cccccc;
  border-radius: 5px;
}

<form>
  <fieldset>
    <legend>Confirm details</legend>
    <div>
      <label for="address">Address:</label>
      <textarea id="address" name="address" readonly>
123 Choco Mountain,
Awesome Ridge,
CA</textarea
      >
    </div>
    <div>
      <label for="instructions">Delivery instructions</label>
      <textarea id="instructions" name="instructions"></textarea>
    </div>
  </fieldset>
  <button type="submit">Confirm</button>
</form>

<p contenteditable>This paragraph is editable; it is read-write.</p>

<p>This paragraph is not editable; it is read-only.</p>

body {
  font-family: sans-serif;
}

p {
  font-size: 150%;
  padding: 5px;
  border-radius: 5px;
}

p:read-only {
  background-color: red;
  color: white;
}

p:read-write {
  background-color: lime;
}