diff --git a/frontend/index.html b/frontend/index.html
index fa2ad66..aca2705 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -762,6 +762,9 @@
   <div class="editor-modal" id="help-modal">
     <div class="editor-container help-container">
       <div class="editor-header">
+        <button class="help-hamburger" id="help-hamburger" title="Sommaire" aria-label="Afficher le sommaire">
+          <i data-lucide="menu" style="width:18px;height:18px"></i>
+        </button>
         <div class="editor-title" id="help-title">Guide d'utilisation ObsiGate</div>
         <div class="editor-actions">
           <button class="editor-btn" id="help-close" title="Fermer l'aide" aria-label="Fermer l'aide">
@@ -769,12 +772,13 @@
           </button>
         </div>
       </div>
+      <div class="help-nav-overlay" id="help-nav-overlay"></div>
       <div class="editor-body help-body" id="help-body">
         <nav class="help-nav" id="help-nav">
           <div class="help-nav-header">
             <div class="help-nav-title">Sommaire</div>
-            <button class="help-nav-toggle" id="help-nav-toggle" title="Afficher/Masquer le sommaire" aria-label="Menu sommaire">
-              <i data-lucide="chevron-down" style="width:16px;height:16px"></i>
+            <button class="help-nav-close" id="help-nav-close" title="Fermer" aria-label="Fermer le sommaire">
+              <i data-lucide="x" style="width:16px;height:16px"></i>
             </button>
           </div>
           <div class="help-nav-search-wrap">
diff --git a/frontend/js/config.js b/frontend/js/config.js
index ea1bbde..03761a2 100644
--- a/frontend/js/config.js
+++ b/frontend/js/config.js
@@ -225,7 +225,9 @@ function initHelpNavigation() {
   const navList = document.getElementById("help-nav-list");
   const nav = document.getElementById("help-nav");
   const searchInput = document.getElementById("help-nav-search");
-  const toggleBtn = document.getElementById("help-nav-toggle");
+  const hamburger = document.getElementById("help-hamburger");
+  const navClose = document.getElementById("help-nav-close");
+  const overlay = document.getElementById("help-nav-overlay");
   const helpContent = document.querySelector(".help-content");
 
   if (!helpBody || !navList || !nav) return;
@@ -235,27 +237,41 @@ function initHelpNavigation() {
   const sectionMap = {};
   allSections.forEach(s => { sectionMap[s.id] = s; });
 
-  // Build text index for content search (section title + text content)
+  // Build text index for content search
   const sectionTextCache = {};
   allSections.forEach(s => {
     sectionTextCache[s.id] = (s.textContent || '').toLowerCase();
   });
 
+  // ── Mobile: open/close TOC slide-over ──
+  function openTOC() {
+    nav.classList.add("open");
+    if (overlay) overlay.classList.add("visible");
+    if (searchInput) setTimeout(() => searchInput.focus(), 150);
+    document.body.style.overflow = "hidden";
+  }
+  function closeTOC() {
+    nav.classList.remove("open");
+    if (overlay) overlay.classList.remove("visible");
+    document.body.style.overflow = "";
+  }
+  function isMobile() { return window.innerWidth <= 768; }
+
+  if (hamburger) hamburger.addEventListener("click", openTOC);
+  if (navClose) navClose.addEventListener("click", closeTOC);
+  if (overlay) overlay.addEventListener("click", closeTOC);
+
   // ── Scroll to section ──
   function scrollToSection(targetId) {
     const section = sectionMap[targetId];
     if (!section) return;
     section.scrollIntoView({ behavior: "smooth", block: "start" });
     section.setAttribute("tabindex", "-1");
-    // On mobile, collapse nav after selection
-    if (window.innerWidth <= 768 && nav) {
-      nav.classList.add("collapsed");
-    }
+    if (isMobile()) closeTOC();
   }
 
-  // ── Focus the content pane (first heading in active section) ──
+  // ── Focus the content pane ──
   function focusContent() {
-    // Find the active section and focus its first heading
     const activeLink = navList.querySelector(".help-nav-link.active:not(.hidden)");
     if (activeLink) {
       const targetId = activeLink.getAttribute("href").substring(1);
@@ -265,12 +281,12 @@ function initHelpNavigation() {
         if (h2) { h2.setAttribute("tabindex", "-1"); h2.focus({ preventScroll: true }); return; }
       }
     }
-    // Fallback: focus the content area itself
     if (helpContent) { helpContent.setAttribute("tabindex", "-1"); helpContent.focus({ preventScroll: true }); }
   }
 
   // ── Focus TOC active link ──
   function focusTOC() {
+    if (isMobile() && !nav.classList.contains("open")) openTOC();
     const activeLink = navList.querySelector(".help-nav-link.active:not(.hidden)");
     if (activeLink) { activeLink.focus(); return; }
     const firstLink = navList.querySelector(".help-nav-link:not(.hidden)");
@@ -301,11 +317,9 @@ function initHelpNavigation() {
       const prev = (currentIdx - 1 + items.length) % items.length;
       items[prev].focus();
     } else if (e.key === "ArrowRight") {
-      // Right arrow: go to content pane
       e.preventDefault();
       focusContent();
     } else if (e.key === "ArrowLeft") {
-      // Left arrow in TOC: stay (prev item)
       e.preventDefault();
       const prev = (currentIdx - 1 + items.length) % items.length;
       items[prev].focus();
@@ -319,12 +333,10 @@ function initHelpNavigation() {
       e.preventDefault();
       const targetId = items[currentIdx].getAttribute("href").substring(1);
       scrollToSection(targetId);
-      // After scrolling, move focus to content
       setTimeout(() => focusContent(), 400);
     }
   });
 
-  // Make nav items focusable
   navList.querySelectorAll("li").forEach((li) => li.setAttribute("role", "none"));
 
   // ── Keyboard navigation in content pane ──
@@ -332,7 +344,6 @@ function initHelpNavigation() {
     helpContent.setAttribute("tabindex", "-1");
     helpContent.addEventListener("keydown", (e) => {
       if (e.key === "ArrowLeft") {
-        // Left arrow in content: go back to TOC
         e.preventDefault();
         focusTOC();
       } else if (e.key === "ArrowUp" && document.activeElement === helpContent) {
@@ -353,7 +364,7 @@ function initHelpNavigation() {
     });
   }
 
-  // ── Search: filter TOC + hide non-matching content sections ──
+  // ── Search: filter TOC + hide non-matching sections + highlight text ──
   let currentQuery = "";
   if (searchInput) {
     searchInput.addEventListener("input", () => {
@@ -369,8 +380,57 @@ function initHelpNavigation() {
     });
   }
 
+  function clearHighlights() {
+    allSections.forEach(section => {
+      section.querySelectorAll(".help-search-highlight").forEach(el => {
+        const parent = el.parentNode;
+        parent.replaceChild(document.createTextNode(el.textContent), el);
+        parent.normalize();
+      });
+    });
+  }
+
+  function highlightText(root, query) {
+    if (!query || query.length < 2) return;
+    const walker = document.createTreeWalker(root, NodeFilter.SHOW_TEXT, null, false);
+    const textNodes = [];
+    while (walker.nextNode()) {
+      const node = walker.currentNode;
+      // Skip nodes inside script, style, or already-highlighted
+      if (node.parentElement && !node.parentElement.closest("script, style, .help-search-highlight, .help-nav")) {
+        textNodes.push(node);
+      }
+    }
+    const regex = new RegExp(`(${query.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')})`, 'gi');
+    textNodes.forEach(node => {
+      const text = node.textContent;
+      if (!regex.test(text)) return;
+      regex.lastIndex = 0;
+      const frag = document.createDocumentFragment();
+      let lastIdx = 0;
+      let match;
+      while ((match = regex.exec(text)) !== null) {
+        if (match.index > lastIdx) {
+          frag.appendChild(document.createTextNode(text.slice(lastIdx, match.index)));
+        }
+        const mark = document.createElement("mark");
+        mark.className = "help-search-highlight";
+        mark.textContent = match[0];
+        frag.appendChild(mark);
+        lastIdx = regex.lastIndex;
+        if (match[0].length === 0) regex.lastIndex++;
+      }
+      if (lastIdx < text.length) {
+        frag.appendChild(document.createTextNode(text.slice(lastIdx)));
+      }
+      node.parentNode.replaceChild(frag, node);
+    });
+  }
+
   function applySearchFilter() {
     const q = currentQuery;
+    // Clear previous highlights
+    clearHighlights();
     // Filter TOC links
     allLinks.forEach((link) => {
       const text = link.textContent.toLowerCase();
@@ -380,7 +440,7 @@ function initHelpNavigation() {
         link.classList.add("hidden");
       }
     });
-    // Filter content sections
+    // Filter content sections + highlight
     allSections.forEach((section) => {
       if (!q) {
         section.classList.remove("help-hidden");
@@ -390,12 +450,13 @@ function initHelpNavigation() {
       const sectionTitle = (section.querySelector("h2, h3")?.textContent || '').toLowerCase();
       if (sectionTitle.includes(q) || sectionText.includes(q)) {
         section.classList.remove("help-hidden");
+        // Highlight matching text in this section
+        highlightText(section, q);
       } else {
         section.classList.add("help-hidden");
       }
     });
     updateActiveLink();
-    // If no visible results, show a message
     ensureNoResultsMessage(q);
   }
 
@@ -415,26 +476,7 @@ function initHelpNavigation() {
     }
   }
 
-  // ── Mobile toggle ──
-  if (toggleBtn) {
-    toggleBtn.addEventListener("click", () => {
-      const wasCollapsed = nav.classList.contains("collapsed");
-      nav.classList.toggle("collapsed");
-      // If expanding, focus search
-      if (wasCollapsed && searchInput) {
-        setTimeout(() => searchInput.focus(), 150);
-      }
-    });
-    // Start expanded on mobile so user sees the TOC immediately
-    // (we use collapsed only after user taps a section or explicitly toggles)
-    window.addEventListener("resize", () => {
-      if (window.innerWidth > 768) {
-        nav.classList.remove("collapsed");
-      }
-    });
-  }
-
-  // ── Scroll spy (IntersectionObserver) ──
+  // ── Scroll spy ──
   function updateActiveLink() {
     const visibleLinks = allLinks.filter(l => !l.classList.contains("hidden"));
     const visibleSections = allSections.filter(s => !s.classList.contains("help-hidden"));
diff --git a/frontend/style.css b/frontend/style.css
index cece3f7..fdc36a4 100644
--- a/frontend/style.css
+++ b/frontend/style.css
@@ -2178,6 +2178,24 @@ select {
 }
 
 /* Help Navigation Menu */
+.help-hamburger {
+  display: none;
+  width: 36px; height: 36px;
+  padding: 0;
+  border: 1px solid var(--border);
+  border-radius: 6px;
+  background: transparent;
+  color: var(--text-secondary);
+  cursor: pointer;
+  align-items: center;
+  justify-content: center;
+  flex-shrink: 0;
+  margin-right: 8px;
+}
+.help-hamburger:hover { color: var(--accent); border-color: var(--accent); }
+.help-nav-overlay {
+  display: none;
+}
 .help-nav {
   width: 260px;
   min-width: 260px;
@@ -2209,7 +2227,7 @@ select {
   letter-spacing: 0.05em;
   color: var(--text-muted);
 }
-.help-nav-toggle {
+.help-nav-close {
   display: none;
   width: 32px; height: 32px;
   padding: 0;
@@ -2221,7 +2239,7 @@ select {
   align-items: center;
   justify-content: center;
 }
-.help-nav-toggle:hover { color: var(--accent); border-color: var(--accent); }
+.help-nav-close:hover { color: var(--accent); border-color: var(--accent); }
 .help-nav-search-wrap {
   padding: 0 12px 8px;
   flex-shrink: 0;
@@ -2290,6 +2308,12 @@ select {
 .help-section.help-hidden {
   display: none;
 }
+.help-search-highlight {
+  background: rgba(250, 204, 21, 0.35);
+  color: inherit;
+  border-radius: 2px;
+  padding: 0 1px;
+}
 
 .help-content {
   flex: 1;
@@ -6393,61 +6417,71 @@ body.popup-mode .content-area {
 
 /* ── Help Modal: Mobile responsive ── */
 @media (max-width: 768px) {
-  .help-container { max-width: 100%; height: 100vh; }
-  .help-container .editor-container {
+  .help-container {
     max-width: 100%;
+    height: 100vh;
     max-height: 100vh;
     border-radius: 0;
   }
+
+  /* Hamburger visible on mobile */
+  .help-hamburger {
+    display: inline-flex;
+  }
+
+  /* TOC: slide-over from left */
+  .help-nav-overlay {
+    display: block;
+    position: fixed;
+    inset: 0;
+    background: rgba(0,0,0,0.5);
+    z-index: 1100;
+    opacity: 0;
+    pointer-events: none;
+    transition: opacity 0.25s ease;
+  }
+  .help-nav-overlay.visible {
+    opacity: 1;
+    pointer-events: auto;
+  }
+
+  .help-nav {
+    position: fixed;
+    top: 0;
+    left: 0;
+    bottom: 0;
+    width: 280px;
+    min-width: 280px;
+    max-height: 100vh;
+    height: 100vh;
+    z-index: 1200;
+    transform: translateX(-100%);
+    transition: transform 0.25s ease;
+    border-right: 1px solid var(--border);
+    box-shadow: 2px 0 16px rgba(0,0,0,0.3);
+    flex-shrink: 0;
+  }
+  .help-nav.open {
+    transform: translateX(0);
+  }
+
+  .help-nav-close {
+    display: inline-flex;
+  }
+
+  /* Content full-width */
   .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;
-    transition: max-height 0.25s ease;
-    overflow: hidden;
-  }
-  .help-nav-header {
-    padding: 10px 16px 6px;
-    cursor: pointer;
-  }
-  .help-nav-toggle {
-    display: inline-flex;
-    transition: transform 0.2s;
-  }
-  .help-nav:not(.collapsed) .help-nav-toggle {
-    transform: rotate(180deg);
-  }
-  .help-nav.collapsed .help-nav-search-wrap,
-  .help-nav.collapsed .help-nav-list {
-    display: none;
-  }
-  .help-nav-search-wrap {
-    padding: 0 12px 6px;
-  }
-  .help-nav-list {
-    max-height: 45vh;
-    flex: none;
-    padding-bottom: 14px;
+    padding: 0;
   }
   .help-content {
-    padding: 14px 12px 40px;
+    padding: 14px 16px 40px;
     flex: 1;
     overflow-y: auto;
     -webkit-overflow-scrolling: touch;
   }
-  .help-content:focus {
-    outline: none;
-  }
+  .help-content:focus { outline: none; }
   .help-hero {
     flex-direction: column;
     gap: 16px;