diff --git a/learn.html b/learn.html
index 813c8da..137a02c 100644
--- a/learn.html
+++ b/learn.html
@@ -3,7 +3,7 @@
   <head>
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
-    <title>Learn · DSA</title>
+    <title>learn · DSA</title>
     <script src="script.js"></script>
     <link
       href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css"
@@ -133,26 +133,26 @@
 
         <ul class="list-unstyled ps-0" id="dsa-sidebar-nav">
           <li class="mb-1">
-              <button
-                class="btn btn-toggle d-inline-flex align-items-center rounded border-0 collapsed"
-                data-bs-toggle="collapse"
-                data-bs-target="#topic-name-collapse"
-                aria-expanded="false"
-              >
-                Big O notation
-              </button>
-              <div class="collapse" id="topic-name-collapse">
-                <ul class="btn-toggle-nav list-unstyled fw-normal pb-1 small">
-                  <li>
-                    <a
-                      href="#"
-                      class="link-body-emphasis d-inline-flex text-decoration-none rounded"
-                      data-lesson="DSA/big-o-summary.md"
-                      >Summary</a
-                    >
-                  </li>
-                </ul>
-              </div>
+            <button
+              class="btn btn-toggle d-inline-flex align-items-center rounded border-0 collapsed"
+              data-bs-toggle="collapse"
+              data-bs-target="#topic-name-collapse"
+              aria-expanded="false"
+            >
+              Big O notation
+            </button>
+            <div class="collapse" id="topic-name-collapse">
+              <ul class="btn-toggle-nav list-unstyled fw-normal pb-1 small">
+                <li>
+                  <a
+                    href="#"
+                    class="link-body-emphasis d-inline-flex text-decoration-none rounded"
+                    data-lesson="DSA/big-o-summary.md"
+                    >Summary</a
+                  >
+                </li>
+              </ul>
+            </div>
           </li>
           <!--
             Add a topic to the sidebar with this pattern (each <button>/collapse