- Добавил Bootstrap и настроил внешний вид форм приложения.

https://www.youtube.com/watch?v=a51jGwoTNmI&list=PLU2ftbIeotGpAYRP9Iv2KLIwK36-o_qYk&index=13

src/main/resources/templates/parts/navbar.ftl

@@ -0,0 +1,29 @@
+<#include "security.ftl">
+<#import "login.ftl" as l>
+
+<nav class="navbar navbar-expand-lg bg-body-tertiary">
+    <div class="container-fluid">
+        <a class="navbar-brand" href="/">Sweater</a>
+        <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent"
+                aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
+            <span class="navbar-toggler-icon"></span>
+        </button>
+        <div class="collapse navbar-collapse" id="navbarSupportedContent">
+            <ul class="navbar-nav me-auto mb-2 mb-lg-0">
+                <li class="nav-item">
+                    <a class="nav-link" aria-current="page" href="/">Home</a>
+                </li>
+                <li class="nav-item">
+                    <a class="nav-link" aria-current="page" href="/main">Messages</a>
+                </li>
+                <#if isAdmin>
+                <li class="nav-item">
+                    <a class="nav-link" aria-current="page" href="/users">Users</a>
+                </li>
+                </#if>
+            </ul>
+        </div>
+        <div class="navbar-text mr-3" >${name}</div>
+        <div><#if name != "unknown"> <@l.logout /> </#if></div>
+    </div>
+</nav>