Add help navigation search, mobile toggle, and scroll spy

frontend/style.css

@@ -2183,14 +2183,23 @@ select {
   min-width: 260px;
   background: color-mix(in srgb, var(--bg-secondary) 94%, var(--bg-primary));
   border-right: 1px solid color-mix(in srgb, var(--border) 85%, transparent);
-  padding: 24px 0;
-  overflow: visible;
+  display: flex;
+  flex-direction: column;
   position: sticky;
   top: 0;
   align-self: flex-start;
-  max-height: none;
+  height: 100%;
+  max-height: calc(90vh - 57px);
   flex-shrink: 0;
   backdrop-filter: blur(12px);
+  overflow: hidden;
+}
+.help-nav-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 20px 16px 10px;
+  flex-shrink: 0;
 }
 .help-nav-title {
   font-family: "JetBrains Mono", monospace;
@@ -2199,27 +2208,62 @@ select {
   text-transform: uppercase;
   letter-spacing: 0.05em;
   color: var(--text-muted);
-  padding: 0 22px 14px;
-  border-bottom: 1px solid color-mix(in srgb, var(--border) 85%, transparent);
-  margin-bottom: 12px;
 }
+.help-nav-toggle {
+  display: none;
+  width: 32px; height: 32px;
+  padding: 0;
+  border: 1px solid var(--border);
+  border-radius: 6px;
+  background: transparent;
+  color: var(--text-secondary);
+  cursor: pointer;
+  align-items: center;
+  justify-content: center;
+}
+.help-nav-toggle:hover { color: var(--accent); border-color: var(--accent); }
+.help-nav-search-wrap {
+  padding: 0 12px 8px;
+  flex-shrink: 0;
+}
+.help-nav-search {
+  width: 100%;
+  padding: 7px 10px;
+  border: 1px solid var(--border);
+  border-radius: 8px;
+  background: var(--bg-primary);
+  color: var(--text-primary);
+  font-size: 0.78rem;
+  outline: none;
+  transition: border-color 0.2s;
+}
+.help-nav-search:focus {
+  border-color: var(--accent);
+}
+.help-nav-search::placeholder { color: var(--text-muted); }
 .help-nav-list {
   list-style: none;
   margin: 0;
-  padding: 0 12px;
+  padding: 0 12px 20px;
+  flex: 1;
+  overflow-y: auto;
+  overflow-x: hidden;
+  scrollbar-width: thin;
+  scrollbar-color: var(--border) transparent;
 }
 .help-nav-list li {
-  margin: 0 0 6px;
+  margin: 0 0 3px;
 }
 .help-nav-link {
   display: block;
-  padding: 10px 12px;
-  font-size: 0.88rem;
+  padding: 8px 12px;
+  font-size: 0.85rem;
   color: var(--text-secondary);
   text-decoration: none;
   transition: all 150ms ease;
   border: 1px solid transparent;
-  border-radius: 12px;
+  border-radius: 8px;
+  outline: none;
 }
 .help-nav-link:hover {
   color: var(--accent);
@@ -2228,6 +2272,11 @@ select {
   text-decoration: none;
   transform: translateX(2px);
 }
+.help-nav-link:focus-visible {
+  outline: 2px solid var(--accent);
+  outline-offset: -2px;
+  border-radius: 8px;
+}
 .help-nav-link.active {
   color: var(--accent);
   background: linear-gradient(135deg, color-mix(in srgb, var(--accent) 16%, transparent), color-mix(in srgb, var(--accent) 7%, transparent));
@@ -2235,6 +2284,9 @@ select {
   font-weight: 600;
   box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--accent) 10%, transparent);
 }
+.help-nav-link.hidden {
+  display: none;
+}
 
 .help-content {
   flex: 1;
@@ -6335,3 +6387,52 @@ body.popup-mode .content-area {
   color: var(--text-muted);
   margin-top: 6px;
 }
+
+/* ── Help Modal: Mobile responsive ── */
+@media (max-width: 768px) {
+  .help-container { max-width: 100%; height: 100vh; }
+  .help-container .editor-container {
+    max-width: 100%;
+    max-height: 100vh;
+    border-radius: 0;
+  }
+  .help-body {
+    flex-direction: column;
+    overflow-y: auto;
+  }
+  .help-nav {
+    width: 100%;
+    min-width: 100%;
+    max-height: none;
+    height: auto;
+    position: relative;
+    top: auto;
+    border-right: none;
+    border-bottom: 1px solid var(--border);
+    flex-shrink: 0;
+  }
+  .help-nav-header {
+    padding: 12px 16px 8px;
+  }
+  .help-nav-toggle {
+    display: inline-flex;  /* visible on mobile */
+  }
+  .help-nav.collapsed .help-nav-search-wrap,
+  .help-nav.collapsed .help-nav-list {
+    display: none;
+  }
+  .help-nav-list {
+    max-height: 40vh;
+    flex: none;
+    padding-bottom: 12px;
+  }
+  .help-content {
+    padding: 16px 12px 40px;
+  }
+  .help-hero {
+    flex-direction: column;
+    gap: 16px;
+  }
+  .help-hero-visual { display: none; }
+  .help-section { padding: 24px 0 20px; }
+}