{% block body %}
{% if session['logged_in'] %}

You're logged in already! <a href="/logout">Logout</a>.

{% else %}
<meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=0.5, maximum-scale=3.0, user-scalable=yes" />
<p>{{ get_flashed_messages()[0] | safe }}</p>

<p>Sign up here.</p>

<form action="/signup" method="POST">
  <p><input type="username" name="username" placeholder="邮箱地址、电话号码"></p>
  <p><input type="password" name="password" placeholder="密码"></p>  
  <p><input type="submit" value="注册"></p>
</form>
{% endif %}
{% endblock %}