templates/login.html

{% extends "base.html" %}
{% block content %}
<div class="container">
  <h2>Sign In</h2>
  <form method="POST" id="loginForm">
    <input type="text" name="username" id="loginUsername" placeholder="Username" required />
    <input type="password" name="password" id="loginPassword" placeholder="Password" required />
    <button type="submit">Login</button>
  </form>
  <p id="loginMessage"></p>
  <p class="switch-page">
    Don't have an account? <a href="{{ url_for('signup') }}">Sign up here</a>
  </p>
</div>
{% endblock %}