Update website

main.css

@@ -60,6 +60,10 @@ a {
   flex-wrap: wrap;
 }
 
+.menu-toggle {
+  display: none;
+}
+
 .site-nav > a,
 .nav-trigger {
   font-size: 0.92rem;
@@ -406,15 +410,50 @@ a {
 
 @media (max-width: 720px) {
   .site-header {
-    flex-direction: column;
-    align-items: flex-start;
+    display: grid;
+    grid-template-columns: 1fr auto;
+    align-items: center;
+  }
+
+  .menu-toggle {
+    display: inline-grid;
+    gap: 5px;
+    width: 44px;
+    height: 44px;
+    place-content: center;
+    border: 1px solid #e5e7eb;
+    border-radius: 8px;
+    background: #fff;
+    cursor: pointer;
+  }
+
+  .menu-toggle span {
+    display: block;
+    width: 20px;
+    height: 2px;
+    background: #111827;
   }
 
   .site-nav {
+    display: flex;
+    grid-column: 1 / -1;
     width: 100%;
     flex-direction: column;
     align-items: stretch;
     gap: 4px;
+    max-height: 0;
+    overflow: hidden;
+    padding-top: 0;
+    opacity: 0;
+    pointer-events: none;
+    transition: max-height 0.25s ease, opacity 0.2s ease, padding-top 0.2s ease;
+  }
+
+  .site-nav.is-open {
+    max-height: 700px;
+    padding-top: 12px;
+    opacity: 1;
+    pointer-events: auto;
   }
 
   .site-nav > a,