collapse nav items on smaller screens

public/site-styles/style.css

@@ -244,4 +244,87 @@
 #theme-toggle #theme-icon {
     display: block;
     line-height: 1;
+}
+
+/* Responsive Navigation Styles */
+/* Hide mobile nav by default (desktop first) */
+.mobile-nav {
+    display: none;
+}
+
+/* Show desktop nav by default */
+.desktop-nav {
+    display: flex;
+}
+
+/* Mobile breakpoint - hide desktop nav and show mobile nav */
+@media (max-width: 768px) {
+    .desktop-nav {
+        display: none;
+    }
+    
+    .mobile-nav {
+        display: flex;
+    }
+    
+    /* Style the dropdown for mobile */
+    .mobile-nav .dropdown {
+        width: 100%;
+    }
+    
+    .mobile-nav .dropdown summary {
+        margin: 0;
+        padding: calc(var(--pico-spacing) * 0.5) var(--pico-spacing);
+        border-radius: var(--pico-border-radius);
+        cursor: pointer;
+        user-select: none;
+    }
+    
+    .mobile-nav .dropdown[open] summary {
+        border-bottom-left-radius: 0;
+        border-bottom-right-radius: 0;
+    }
+    
+    .mobile-nav .dropdown ul {
+        position: absolute;
+        top: 100%;
+        left: 0;
+        right: 0;
+        background: var(--pico-background-color);
+        border: 1px solid var(--pico-muted-border-color);
+        border-top: none;
+        border-radius: 0 0 var(--pico-border-radius) var(--pico-border-radius);
+        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+        z-index: 1000;
+        margin: 0;
+        padding: 0;
+        list-style: none;
+    }
+    
+    .mobile-nav .dropdown ul li {
+        margin: 0;
+        border-bottom: 1px solid var(--pico-muted-border-color);
+    }
+    
+    .mobile-nav .dropdown ul li:last-child {
+        border-bottom: none;
+    }
+    
+    .mobile-nav .dropdown ul li a {
+        display: block;
+        padding: calc(var(--pico-spacing) * 0.75) var(--pico-spacing);
+        text-decoration: none;
+        color: var(--pico-color);
+        transition: background-color 0.2s ease;
+    }
+    
+    .mobile-nav .dropdown ul li a:hover {
+        background-color: var(--pico-muted-color);
+        opacity: 0.1;
+    }
+    
+    /* Ensure proper positioning context */
+    .mobile-nav li {
+        position: relative;
+    }
 }