diff --git a/conversations.php b/conversations.php
index 5984e77..9e1f612 100644
--- a/conversations.php
+++ b/conversations.php
@@ -556,20 +556,59 @@
         }
 
         @media (max-width: 768px) {
+            /* Fullscreen sidebar that can slide in/out */
+            .chat-container { padding: 0; gap: 0; }
             .chat-sidebar {
                 width: 100%;
-                position: absolute;
-                z-index: 1000;
+                position: fixed;
+                top: 0;
+                left: 0;
+                z-index: 1100;
                 height: 100vh;
+                transform: translateX(0);
+                transition: transform 240ms ease;
+                box-shadow: none;
             }
-            
+
+            /* Hidden by default on mobile. .open will show it */
+            .chat-sidebar.mobile-hidden { transform: translateX(-110%); }
+
             .chat-main {
                 width: 100%;
+                margin-left: 0;
+                display: flex;
+                flex-direction: column;
+                height: 100vh;
             }
-            
-            .chat-sidebar.show-chat {
-                transform: translateX(-100%);
+
+            /* Header adjustment */
+            .chat-header { padding: 10px 12px; gap: 8px; }
+            .chat-header-avatar { width: 38px; height: 38px; }
+
+            /* Fix input to bottom to emulate mobile chat apps */
+            .chat-input {
+                position: fixed;
+                left: 0;
+                right: 0;
+                bottom: 0;
+                padding: 10px;
+                background: #fff;
+                z-index: 1200;
+                border-top: 1px solid #e9eef2;
             }
+
+            /* Give chat area bottom padding so messages are not hidden under input */
+            .chat-conversations { padding-bottom: 120px; }
+
+            /* Compact avatars and message bubble width */
+            .conversation-avatar { width: 40px; height: 40px; }
+            .message-bubble { max-width: 85%; font-size: 15px; }
+
+            /* Quick replies panel adapt */
+            .quick-replies-panel { left: 8px; right: 8px; bottom: 70px; max-height: 160px; }
+
+            /* Show a small back button in header to open sidebar */
+            #sidebar-toggle { display: inline-flex; }
         }
 
         .reply-preview {
@@ -652,6 +691,7 @@
 
             <div id="chat-area" style="display: none; height: 100%; flex-direction: column;">
                 <div class="chat-header">
+                        <button id="sidebar-toggle" class="btn btn-sm btn-outline-light d-md-none me-2" style="display:none; border-radius:8px; padding:6px 8px;" title="Volver a conversaciones"><i class="fas fa-bars"></i></button>
                     <div class="chat-header-avatar" id="chat-avatar">
                         <i class="fas fa-user"></i>
                     </div>
@@ -966,25 +1006,6 @@
                         }
                     }
                 };
-                openBtn.className = notification.cool ? 'btn btn-sm btn-light' : 'btn btn-sm btn-primary';
-                openBtn.textContent = 'Abrir';
-                openBtn.onclick = async () => {
-                    try {
-                        await fetch('api/mark_notification_read.php', {method:'POST', headers:{'Content-Type':'application/json'}, body: JSON.stringify({id: notification.id})});
-                    } catch(e) { console.warn('mark_notification_read failed', e); }
-                    let data = {};
-                    try { data = notification.data ? JSON.parse(notification.data) : {}; } catch(e) {}
-                    const userId = data.user_id || notification.user_id;
-                    if (userId) {
-                        const conv = this.conversations.find(c => c.user_id == userId);
-                        if (conv) {
-                            this.openConversation(conv.user_id, conv.name, conv.phone_number);
-                        } else {
-                            this.openConversation(userId, 'Usuario', '');
-                        }
-                    }
-                    removeToast();
-                };
 
                 const dismiss = document.createElement('button');
                 dismiss.className = 'btn btn-sm btn-outline-secondary';
@@ -1100,6 +1121,27 @@
                     });
                 }
 
+                // Mobile: sidebar toggle
+                const sidebar = document.querySelector('.chat-sidebar');
+                const sidebarToggle = document.getElementById('sidebar-toggle');
+                if (sidebarToggle && sidebar) {
+                    sidebarToggle.addEventListener('click', (ev) => {
+                        ev.preventDefault();
+                        // toggle mobile-hidden class
+                        sidebar.classList.toggle('mobile-hidden');
+                    });
+                    // ensure sidebar hidden by default on small screens
+                    const applyInitialMobile = () => {
+                        if (window.innerWidth <= 768) {
+                            sidebar.classList.add('mobile-hidden');
+                        } else {
+                            sidebar.classList.remove('mobile-hidden');
+                        }
+                    };
+                    applyInitialMobile();
+                    window.addEventListener('resize', applyInitialMobile);
+                }
+
                 const stopRecBtn = document.getElementById('stop-recording');
                 if (stopRecBtn) stopRecBtn.addEventListener('click', () => this.stopRecording());
                 const cancelRecBtn = document.getElementById('cancel-recording');
@@ -1415,6 +1457,12 @@
                     const releaseBtn = document.getElementById('release-hold-btn');
                     const markUnreadBtn = document.getElementById('mark-unread-btn');
 
+                    // On mobile, hide the sidebar when opening a conversation so chat occupies full screen
+                    const sidebar = document.querySelector('.chat-sidebar');
+                    if (sidebar && window.innerWidth <= 768) {
+                        sidebar.classList.add('mobile-hidden');
+                    }
+
                     if (markUnreadBtn) {
                         markUnreadBtn.style.display = 'inline-block';
                         markUnreadBtn.onclick = async () => {
@@ -2353,84 +2401,66 @@
             }
             
             renderMediaMessage(message) {
-                if (!message.media_url) return '';
-                
-                const mediaType = message.message_type;
-                const mediaUrl = message.media_url;
-                const caption = message.content;
-                
+                if (!message) return '';
+                const mediaType = message.message_type || message.media_type || 'text';
+                const mediaUrl = message.media_url || message.media_url_external || '';
+                const caption = message.content || '';
+                const localFile = message.local_file || '';
+                const localThumb = message.local_thumb || '';
+                const thumb = localThumb ? (`/${localThumb}`) : (localFile ? (`/${localFile}`) : (message.media_url_external || mediaUrl));
+
+                let full = '';
+                if (localFile) {
+                    full = `/api/version/media-url.php?local=${encodeURIComponent(localFile)}`;
+                } else if (message.media_url_external) {
+                    if (message.media_url_external.indexOf('api/get_media.php?id=') !== -1) {
+                        const parts = message.media_url_external.split('id=');
+                        const mid = parts[1] ? decodeURIComponent(parts[1]) : '';
+                        full = `/api/version/media-url.php?id=${encodeURIComponent(mid)}`;
+                    } else if (/^https?:\/\//i.test(message.media_url_external)) {
+                        full = message.media_url_external;
+                    } else {
+                        full = `/api/version/media-url.php?url=${encodeURIComponent(message.media_url_external)}`;
+                    }
+                } else {
+                    full = mediaUrl || '';
+                }
+
                 switch (mediaType) {
                     case 'image':
-                        // Usar miniatura local si existe, al abrir expandir con el archivo local completo o con media-url redirect
-                        const thumb = msg.local_thumb ? (`/${msg.local_thumb}`) : (msg.local_file ? (`/${msg.local_file}`) : (msg.media_url_external || mediaUrl));
-                        let full = '';
-                        if (msg.local_file) {
-                            full = `/api/version/media-url.php?local=${encodeURIComponent(msg.local_file)}`;
-                        } else if (msg.media_url_external) {
-                            // Si viene una ruta del tipo api/get_media.php?id=XXX extraer id
-                            if (msg.media_url_external.indexOf('api/get_media.php?id=') !== -1) {
-                                const parts = msg.media_url_external.split('id=');
-                                const mid = parts[1] ? decodeURIComponent(parts[1]) : '';
-                                full = `/api/version/media-url.php?id=${encodeURIComponent(mid)}`;
-                            } else if (/^https?:\/\//i.test(msg.media_url_external)) {
-                                // URL directa
-                                full = msg.media_url_external;
-                            } else {
-                                // fallback: pasar como url
-                                full = `/api/version/media-url.php?url=${encodeURIComponent(msg.media_url_external)}`;
-                            }
-                        } else {
-                            full = mediaUrl || '';
-                        }
                         return `
                             <div class="message-media">
-                                <a href="#" onclick="openImageLightbox(${JSON.stringify(full)}); return false;" title="Abrir imagen">
-                                    <img src="${thumb}" alt="Imagen" style="cursor:zoom-in">
+                                <a href="#" data-full="${escapeHtml(full)}" data-type="image" data-caption="${escapeHtml(caption)}" onclick="openMediaLightbox(this.dataset.full, this.dataset.type, this.dataset.caption); return false;" title="Abrir imagen">
+                                    <img src="${escapeHtml(thumb)}" alt="Imagen" style="cursor:zoom-in">
                                 </a>
                             </div>
-                            ${caption ? `<div>${caption}</div>` : ''}
+                            ${caption ? `<div>${escapeHtml(caption)}</div>` : ''}
                         `;
-                        
                     case 'video':
-                        let videoSrc = '';
-                        if (msg.local_file) {
-                            videoSrc = `/${msg.local_file}`;
-                        } else if (msg.media_url_external) {
-                            if (msg.media_url_external.indexOf('api/get_media.php?id=') !== -1) {
-                                const parts = msg.media_url_external.split('id=');
-                                const mid = parts[1] ? decodeURIComponent(parts[1]) : '';
-                                videoSrc = `/api/version/media-url.php?id=${encodeURIComponent(mid)}`;
-                            } else if (/^https?:\/\//i.test(msg.media_url_external)) {
-                                videoSrc = msg.media_url_external;
-                            } else {
-                                videoSrc = `/api/version/media-url.php?url=${encodeURIComponent(msg.media_url_external)}`;
-                            }
-                        } else {
-                            videoSrc = mediaUrl;
-                        }
                         return `
                             <div class="message-media">
-                                <video controls>
-                                    <source src="${videoSrc}" type="video/mp4">
-                                    Tu navegador no soporta video.
-                                </video>
+                                <a href="#" data-full="${escapeHtml(full)}" data-type="video" data-caption="${escapeHtml(caption)}" onclick="openMediaLightbox(this.dataset.full, this.dataset.type, this.dataset.caption); return false;" title="Abrir video">
+                                    <div style="position:relative; display:inline-block;">
+                                        <img src="${escapeHtml(thumb)}" alt="Video" style="cursor:zoom-in; max-width:100%; border-radius:6px;">
+                                        <div style="position:absolute; left:50%; top:50%; transform:translate(-50%,-50%); font-size:28px; color:white; text-shadow:0 1px 6px rgba(0,0,0,0.6);"><i class="fas fa-play-circle"></i></div>
+                                    </div>
+                                </a>
                             </div>
-                            ${caption ? `<div>${caption}</div>` : ''}
+                            ${caption ? `<div>${escapeHtml(caption)}</div>` : ''}
                         `;
-                        
-                    case 'audio':
+                    case 'audio': {
                         let audioSrc = '';
-                        if (msg.local_file) {
-                            audioSrc = `/${msg.local_file}`;
-                        } else if (msg.media_url_external) {
-                            if (msg.media_url_external.indexOf('api/get_media.php?id=') !== -1) {
-                                const parts = msg.media_url_external.split('id=');
+                        if (localFile) {
+                            audioSrc = `/${localFile}`;
+                        } else if (message.media_url_external) {
+                            if (message.media_url_external.indexOf('api/get_media.php?id=') !== -1) {
+                                const parts = message.media_url_external.split('id=');
                                 const mid = parts[1] ? decodeURIComponent(parts[1]) : '';
                                 audioSrc = `/api/version/media-url.php?id=${encodeURIComponent(mid)}`;
-                            } else if (/^https?:\/\//i.test(msg.media_url_external)) {
-                                audioSrc = msg.media_url_external;
+                            } else if (/^https?:\/\//i.test(message.media_url_external)) {
+                                audioSrc = message.media_url_external;
                             } else {
-                                audioSrc = `/api/version/media-url.php?url=${encodeURIComponent(msg.media_url_external)}`;
+                                audioSrc = `/api/version/media-url.php?url=${encodeURIComponent(message.media_url_external)}`;
                             }
                         } else {
                             audioSrc = mediaUrl;
@@ -2438,27 +2468,25 @@
                         return `
                             <div class="message-media">
                                 <audio controls>
-                                    <source src="${audioSrc}" type="audio/mpeg">
+                                    <source src="${escapeHtml(audioSrc)}" type="audio/mpeg">
                                     Tu navegador no soporta audio.
                                 </audio>
                             </div>
                         `;
-                        
-                    case 'document':
-                        // Para documentos no descargamos automáticamente; abrir la URL externa (o la redirección por media id) para descargar
+                    }
+                    case 'document': {
                         let docUrl = '';
-                        if (msg.local_file) {
-                            docUrl = `/api/version/media-url.php?local=${encodeURIComponent(msg.local_file)}&download=1`;
-                        } else if (msg.media_url_external) {
-                            if (msg.media_url_external.indexOf('api/get_media.php?id=') !== -1) {
-                                const parts = msg.media_url_external.split('id=');
+                        if (localFile) {
+                            docUrl = `/api/version/media-url.php?local=${encodeURIComponent(localFile)}&download=1`;
+                        } else if (message.media_url_external) {
+                            if (message.media_url_external.indexOf('api/get_media.php?id=') !== -1) {
+                                const parts = message.media_url_external.split('id=');
                                 const mid = parts[1] ? decodeURIComponent(parts[1]) : '';
                                 docUrl = `/api/version/media-url.php?id=${encodeURIComponent(mid)}&download=1`;
-                            } else if (/^https?:\/\//i.test(msg.media_url_external)) {
-                                docUrl = `/api/version/media-url.php?url=${encodeURIComponent(msg.media_url_external)}&download=1`;
+                            } else if (/^https?:\/\//i.test(message.media_url_external)) {
+                                docUrl = `/api/version/media-url.php?url=${encodeURIComponent(message.media_url_external)}&download=1`;
                             } else {
-                                // fallback
-                                docUrl = `/api/version/media-url.php?url=${encodeURIComponent(msg.media_url_external)}&download=1`;
+                                docUrl = `/api/version/media-url.php?url=${encodeURIComponent(message.media_url_external)}&download=1`;
                             }
                         }
                         if (!docUrl) {
@@ -2466,7 +2494,7 @@
                                 <div class="message-document disabled">
                                     <i class="fas fa-file-pdf"></i>
                                     <div class="document-info">
-                                        <div class="document-name">${caption || 'Documento'}</div>
+                                        <div class="document-name">${escapeHtml(caption || 'Documento')}</div>
                                         <div class="document-size text-muted">No disponible para descargar</div>
                                     </div>
                                 </div>
@@ -2476,17 +2504,17 @@
                             <div class="message-document">
                                 <i class="fas fa-file-pdf"></i>
                                 <div class="document-info">
-                                    <div class="document-name">${caption || 'Documento'}</div>
+                                    <div class="document-name">${escapeHtml(caption || 'Documento')}</div>
                                     <div class="document-size">
-                                        <a href="${docUrl}" target="_blank" rel="noopener noreferrer" ${docUrl && docUrl.indexOf('download=1') !== -1 ? 'download' : ''}>Descargar</a>
+                                        <a href="${escapeHtml(docUrl)}" target="_blank" rel="noopener noreferrer" ${docUrl && docUrl.indexOf('download=1') !== -1 ? 'download' : ''}>Descargar</a>
                                     </div>
                                 </div>
                                 <i class="fas fa-download"></i>
                             </div>
                         `;
-                        
+                    }
                     default:
-                        return caption || '';
+                        return escapeHtml(caption) || '';
                 }
             }
         }
@@ -2498,6 +2526,63 @@
             }
         }
 
+        // Helper para iconos de archivos (copiado de chat_window)
+        function getFileIcon(filename) {
+            if (!filename) return 'fas fa-file text-muted';
+            const ext = String(filename).split('.').pop().toLowerCase();
+            const iconMap = {
+                'pdf': 'fas fa-file-pdf text-danger',
+                'doc': 'fas fa-file-word text-primary',
+                'docx': 'fas fa-file-word text-primary',
+                'xls': 'fas fa-file-excel text-success',
+                'xlsx': 'fas fa-file-excel text-success',
+                'ppt': 'fas fa-file-powerpoint text-warning',
+                'pptx': 'fas fa-file-powerpoint text-warning',
+                'zip': 'fas fa-file-archive text-secondary',
+                'rar': 'fas fa-file-archive text-secondary',
+                'txt': 'fas fa-file-alt text-muted',
+                'csv': 'fas fa-file-csv text-success'
+            };
+            return iconMap[ext] || 'fas fa-file text-muted';
+        }
+
+        // Media lightbox helper (image/video with download)
+        function openMediaLightbox(url, type = 'image', caption = '') {
+            if (!url) {
+                showAlert && showAlert('Media no disponible', 'warning');
+                return;
+            }
+            const body = document.getElementById('imageLightboxBody');
+            const cap = document.getElementById('imageLightboxCaption');
+            const downloadBtn = document.getElementById('imageLightboxDownload');
+            if (!body || !cap) return;
+            // clear existing content
+            body.innerHTML = '';
+
+            // Decide rendering by type or by URL extension
+            const isVideo = (type === 'video') || /\.(mp4|webm|ogg)(\?|$)/i.test(url);
+            if (isVideo) {
+                body.innerHTML = `<video controls class="w-100" style="border-radius:10px;"><source src="${escapeHtml(url)}" type="video/mp4">Tu navegador no soporta video.</video>`;
+            } else {
+                body.innerHTML = `<img src="${escapeHtml(url)}" class="img-fluid w-100" style="border-radius:10px;">`;
+            }
+
+            cap.textContent = caption || '';
+            if (downloadBtn) {
+                downloadBtn.href = url;
+                downloadBtn.style.display = 'inline-block';
+            }
+
+            const modalEl = document.getElementById('imageLightboxModal');
+            const bsModal = new bootstrap.Modal(modalEl);
+            bsModal.show();
+        }
+
+        // backward compatibility wrapper
+        function openImageLightbox(url, caption = '') {
+            openMediaLightbox(url, 'image', caption);
+        }
+
         // Inicializar cuando la página cargue
         let chat;
         document.addEventListener('DOMContentLoaded', () => {
@@ -2505,5 +2590,22 @@
             window.chatApp = chat; // Exponer globalmente para funciones auxiliares
         });
     </script>
+
+    <!-- Lightbox Modal -->
+    <div class="modal fade" id="imageLightboxModal" tabindex="-1" aria-hidden="true">
+        <div class="modal-dialog modal-dialog-centered modal-lg">
+            <div class="modal-content bg-transparent border-0">
+                <div class="modal-body p-0 position-relative">
+                    <button type="button" class="btn-close btn-close-white position-absolute top-0 end-0 m-3" data-bs-dismiss="modal" aria-label="Cerrar" style="z-index:10;"></button>
+                    <div id="imageLightboxBody" style="max-height:75vh; overflow:auto;"></div>
+                    <div id="imageLightboxCaption" class="mt-2 text-center text-white small"></div>
+                    <div class="position-absolute bottom-0 end-0 m-3">
+                        <a id="imageLightboxDownload" class="btn btn-sm btn-light" href="#" target="_blank" download style="display:none;"><i class="fas fa-download"></i> Descargar</a>
+                    </div>
+                </div>
+            </div>
+        </div>
+    </div>
+
 </body>
 </html>
\ No newline at end of file