diff --git a/frontend/index.html b/frontend/index.html
index bef8837..ef7deaa 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -762,7 +762,7 @@
   <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" onclick="var n=document.getElementById('help-nav');var o=document.getElementById('help-nav-overlay');if(n){n.classList.toggle('open');if(o)o.classList.toggle('visible');var s=document.getElementById('help-nav-search');if(n.classList.contains('open')&&s)setTimeout(function(){s.focus()},150);document.body.style.overflow=n.classList.contains('open')?'hidden':''}">
+        <button class="help-hamburger" id="help-hamburger" title="Sommaire" aria-label="Afficher le sommaire" onclick="var n=document.getElementById('help-nav');if(n){n.style.display=n.style.display==='none'?'flex':'none'}">
           <i data-lucide="menu" style="width:18px;height:18px"></i>
         </button>
         <div class="editor-title" id="help-title">Guide d'utilisation ObsiGate</div>
@@ -772,14 +772,10 @@
           </button>
         </div>
       </div>
-      <div class="help-nav-overlay" id="help-nav-overlay" onclick="var n=document.getElementById('help-nav');var o=document.getElementById('help-nav-overlay');if(n)n.classList.remove('open');if(o)o.classList.remove('visible');document.body.style.overflow=''"></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-close" id="help-nav-close" title="Fermer" aria-label="Fermer le sommaire" onclick="var n=document.getElementById('help-nav');var o=document.getElementById('help-nav-overlay');if(n)n.classList.remove('open');if(o)o.classList.remove('visible');document.body.style.overflow=''">
-              <i data-lucide="x" style="width:16px;height:16px"></i>
-            </button>
           </div>
           <div class="help-nav-search-wrap">
             <input type="text" class="help-nav-search" id="help-nav-search" placeholder="Rechercher dans l'aide..." autocomplete="off" spellcheck="false">
diff --git a/frontend/js/auth.js b/frontend/js/auth.js
index c4105f0..5597a70 100644
--- a/frontend/js/auth.js
+++ b/frontend/js/auth.js
@@ -465,7 +465,7 @@ const AdminPanel = {
       <div class="admin-form-card">
         <h3>${title}</h3>
         <form id="admin-user-form">
-          ${!isEdit ? '<div class="form-group"><label>Nom d\'utilisateur</label><input type="text" name="username" required pattern="[a-zA-Z0-9_-]{2,32}" placeholder="username"></div>' : ""}
+          ${!isEdit ? '<div class="form-group"><label>Nom d\'utilisateur</label><input type="text" name="username" required pattern="[a-zA-Z0-9_\-]{2,32}" placeholder="username"></div>' : ""}
           <div class="form-group"><label>Nom affiché</label><input type="text" name="display_name" value="${isEdit ? user.display_name || "" : ""}"></div>
           <div class="form-group"><label>${isEdit ? "Nouveau mot de passe (vide = inchangé)" : "Mot de passe"}</label><input type="password" name="password" ${!isEdit ? 'required minlength="8"' : ""} placeholder="${isEdit ? "Laisser vide pour ne pas changer" : "Min. 8 caractères"}"></div>
           <div class="form-group"><label>Rôle</label><select name="role"><option value="user" ${isEdit && user.role === "user" ? "selected" : ""}>Utilisateur</option><option value="admin" ${isEdit && user.role === "admin" ? "selected" : ""}>Admin</option></select></div>
diff --git a/frontend/js/config.js b/frontend/js/config.js
index bb2590e..ce59ef4 100644
--- a/frontend/js/config.js
+++ b/frontend/js/config.js
@@ -195,6 +195,9 @@ function initHelpModal() {
     modal.classList.add("active");
     closeHeaderMenu();
     safeCreateIcons();
+    // Reset TOC to CSS default (mobile: hidden, desktop: visible)
+    const nav = document.getElementById("help-nav");
+    if (nav) nav.style.display = '';
     if (!helpNavInitialized) {
       initHelpNavigation();
       helpNavInitialized = true;
@@ -220,9 +223,6 @@ function initHelpNavigation() {
   const navList = document.getElementById("help-nav-list");
   const nav = document.getElementById("help-nav");
   const searchInput = document.getElementById("help-nav-search");
-  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;
@@ -238,23 +238,16 @@ function initHelpNavigation() {
     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 = "";
-  }
+  // ── Mobile: simple display toggle ──
   function isMobile() { return window.innerWidth <= 768; }
-
-  if (hamburger) hamburger.addEventListener("click", openTOC);
-  if (navClose) navClose.addEventListener("click", closeTOC);
-  if (overlay) overlay.addEventListener("click", closeTOC);
+  function toggleTOC() {
+    if (nav.style.display === 'none' || nav.style.display === '') {
+      nav.style.display = 'flex';
+      if (searchInput) setTimeout(() => searchInput.focus(), 150);
+    } else {
+      nav.style.display = 'none';
+    }
+  }
 
   // ── Scroll to section ──
   function scrollToSection(targetId) {
@@ -262,7 +255,7 @@ function initHelpNavigation() {
     if (!section) return;
     section.scrollIntoView({ behavior: "smooth", block: "start" });
     section.setAttribute("tabindex", "-1");
-    if (isMobile()) closeTOC();
+    if (isMobile()) nav.style.display = 'none';
   }
 
   // ── Focus the content pane ──
@@ -281,7 +274,9 @@ function initHelpNavigation() {
 
   // ── Focus TOC active link ──
   function focusTOC() {
-    if (isMobile() && !nav.classList.contains("open")) openTOC();
+    if (isMobile() && (nav.style.display === 'none' || nav.style.display === '')) {
+      nav.style.display = 'flex';
+    }
     const activeLink = navList.querySelector(".help-nav-link.active:not(.hidden)");
     if (activeLink) { activeLink.focus(); return; }
     const firstLink = navList.querySelector(".help-nav-link:not(.hidden)");
diff --git a/frontend/style.css b/frontend/style.css
index 0da9f35..55d3f1c 100644
--- a/frontend/style.css
+++ b/frontend/style.css
@@ -2193,9 +2193,6 @@ select {
   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;
@@ -2227,19 +2224,6 @@ select {
   letter-spacing: 0.05em;
   color: var(--text-muted);
 }
-.help-nav-close {
-  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-close:hover { color: var(--accent); border-color: var(--accent); }
 .help-nav-search-wrap {
   padding: 0 12px 8px;
   flex-shrink: 0;
@@ -6449,49 +6433,28 @@ body.popup-mode .content-area {
     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;
-  }
-
+  /* TOC: collapsible block at top (not slide-over) */
   .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);
+    position: static;
+    width: 100%;
+    min-width: 100%;
+    max-height: none;
+    height: auto;
+    z-index: auto;
+    transform: none;
+    transition: none;
+    border-right: none;
+    border-bottom: 1px solid var(--border);
+    box-shadow: none;
     flex-shrink: 0;
+    display: none;  /* hidden by default on mobile */
   }
-  .help-nav.open {
-    transform: translateX(0);
-  }
-
-  .help-nav-close {
-    display: inline-flex;
+  .help-nav-header {
+    padding: 10px 16px 6px;
   }
 
   /* Content full-width */