feat: guide d'utilisation - couverture complete, telechargement MD/PDF, section Architecture Mermaid, guide desktop elargi (#105, BUG-067)

frontend/style.css

@@ -8146,6 +8146,29 @@ body.popup-mode .content-area {
 .cp-browse-filter:focus { border-color: var(--accent); }
 .cp-browse-filter::placeholder { color: var(--text-muted); }
 
+/* ── Help Modal: desktop = wider reading (#105) ──
+   The Tauri shell (body.desktop-mode) and wide web viewports get the full
+   reading layout instead of the 1320px modal cap. */
+body.desktop-mode .help-container {
+  max-width: 1760px;
+  width: 96vw;
+}
+body.desktop-mode .help-content {
+  max-width: 1440px;
+  padding: 36px 56px 64px;
+}
+body.desktop-mode .editor-container {
+  max-height: 94vh;
+}
+@media (min-width: 1400px) {
+  .help-container {
+    max-width: min(1640px, calc(100vw - 48px));
+  }
+  .help-content {
+    max-width: 1280px;
+  }
+}
+
 /* ── Help Modal: Mobile responsive ── */
 @media (max-width: 768px) {
   .help-container,