Refactor shared layouts and remove unused CSS

app/templates/register.html

@@ -1,9 +1,12 @@
-<h1>Register</h1>
-
-<form method="POST">
-  <input name="username" placeholder="Username" required />
-  <input name="password" type="password" required />
-  <button type="submit">Create Account</button>
-</form>
-
-<a href="{{ url_for('auth.login') }}">Back to Login</a>
+{% extends "base_public.html" %} {% block title %}Register{% endblock %} {%
+block content %}
+<section class="public-card">
+  <h1>Register</h1>
+  <form method="POST" class="auth-form">
+    <input name="username" placeholder="Username" required />
+    <input name="password" type="password" placeholder="Password" required />
+    <button type="submit" class="link-button">Create Account</button>
+  </form>
+  <a href="{{ url_for('auth.login') }}">Back to Login</a>
+</section>
+{% endblock %}