{% load utilities %}

{# Note - submit button not included. #}
<form class="form-horizontal" role="form" method="POST"
  action="{% url 'account_login' %}" id="login-form">
  {% csrf_token %}

  <input type="hidden" name="next" value="{% next_page %}">

  {% if form.errors %}
  <div class="alert alert-danger">
    <b>Error:</b>

    <br>

    <p>Your username and password didn't match. Please try again.</p>
  </div>
  {% endif %}

  <div class="form-group">
    <label for="login-username"
      class="col-sm-2 control-label">Username</label>

    <div class="col-sm-10">
      <input type="text" class="form-control" name="username"
        id="login-username" placeholder="Username"
        value="{{ form.username.value|default:'' }}">
    </div>
  </div>

  <div class="form-group">
    <label for="login-password"
      class="col-sm-2 control-label">Password</label>

    <div class="col-sm-10">
      <input type="password" class="form-control" name="password"
        id="login-password" placeholder="Password"
        value="{{ form.password.value|default:'' }}">
    </div>
  </div>
</form>

{% load utilities %}

{# Note - submit button not included. #}
<form class="form-horizontal" role="form" method="POST"
  action="{% url 'account_login' %}" id="login-form">
  {% csrf_token %}

  <input type="hidden" name="next" value="{% next_page %}">

  {% if form.errors %}
  <div class="alert alert-danger">
    <p>
      <strong>Error:</strong> Your username and password didn't match. Please
      try again.
    </p>

    <p>
      Please also verify that you're logging in with your username and
      <strong>not your email address</strong>.
    </p>
  </div>
  {% endif %}

  <div class="form-group">
    <label for="login-username"
      class="col-sm-2 control-label">Username</label>

    <div class="col-sm-10">
      <input type="text" class="form-control" name="username"
        id="login-username" placeholder="Username"
        value="{{ form.username.value|default:'' }}">
    </div>
  </div>

  <div class="form-group">
    <label for="login-password"
      class="col-sm-2 control-label">Password</label>

    <div class="col-sm-10">
      <input type="password" class="form-control" name="password"
        id="login-password" placeholder="Password"
        value="{{ form.password.value|default:'' }}">
    </div>
  </div>
</form>

Add not about logging in with username
Add not about logging in with username
