set up main structure of the UI

UI/templates/login.html

@@ -0,0 +1,27 @@
+{% extends "base.html" %}
+
+{% block title %}Login{% endblock %}
+
+{% block content %}
+<div class="row justify-content-center">
+    <div class="col-md-6">
+        <h2 class="text-center">Login</h2>
+        {% if error %}
+        <div class="alert alert-danger" role="alert">
+            {{ error }}
+        </div>
+        {% endif %}
+        <form method="POST" action="/login">
+            <div class="form-group">
+                <label for="username">Username</label>
+                <input type="text" class="form-control" id="username" name="username" placeholder="Enter your username" required>
+            </div>
+            <div class="form-group">
+                <label for="password">Password</label>
+                <input type="password" class="form-control" id="password" name="password" placeholder="Enter your password" required>
+            </div>
+            <button type="submit" class="btn btn-primary btn-block">Login</button>
+        </form>
+    </div>
+</div>
+{% endblock %}