diff --git a/public/app.mjs b/public/app.mjs
index 2badb0a..907a610 100644
--- a/public/app.mjs
+++ b/public/app.mjs
@@ -179,13 +179,20 @@ function build_image_grid(grid_el, images, on_delete) {
 	grid_el.replaceChildren(...images.map(img_id => {
 		const thumb = clone('t-image-thumb');
 		const link = qs(thumb, '.thumb-link');
-		link.href = `/img/${img_id}`;
+		link.href = '#';
+		link.addEventListener('click', (e) => { e.preventDefault(); open_lightbox(`/img/${img_id}`); });
 		qs(thumb, '.thumb-img').src = `/img/${img_id}`;
 		qs(thumb, '.thumb-delete').addEventListener('click', () => on_delete(img_id));
 		return thumb;
 	}));
 }
 
+function open_lightbox(src) {
+	const lb = document.getElementById('lightbox');
+	document.getElementById('lightbox-img').src = src;
+	lb.hidden = false;
+}
+
 // ---------------------------------------------------------------------------
 // Render: Components section (split pane)
 // ---------------------------------------------------------------------------
@@ -355,6 +362,8 @@ function render_detail_panel() {
 				thumb.className = 'pdf-thumb';
 				thumb.src = `/pdf/${pdf.thumb_filename}`;
 				thumb.alt = '';
+				thumb.style.cursor = 'zoom-in';
+				thumb.addEventListener('click', () => open_lightbox(`/pdf/${pdf.thumb_filename}`));
 				row.appendChild(thumb);
 			}
 
@@ -437,9 +446,8 @@ function build_detail_inv_entry(entry) {
 		if (cell_filename) {
 			const thumb = document.createElement('a');
 			thumb.className = 'thumb-link cell-thumb-link';
-			thumb.href = `/img/${cell_filename}`;
-			thumb.target = '_blank';
-			thumb.rel = 'noopener';
+			thumb.href = '#';
+			thumb.addEventListener('click', (e) => { e.preventDefault(); open_lightbox(`/img/${cell_filename}`); });
 			const img = document.createElement('img');
 			img.className = 'thumb-img';
 			img.src = `/img/${cell_filename}`;
@@ -1376,6 +1384,8 @@ function render_file_picker_list() {
 			thumb.className = 'fp-thumb';
 			thumb.src = `/pdf/${pdf.thumb_filename}`;
 			thumb.alt = '';
+			thumb.style.cursor = 'zoom-in';
+			thumb.addEventListener('click', () => open_lightbox(`/pdf/${pdf.thumb_filename}`));
 			row.appendChild(thumb);
 		}
 
@@ -1940,6 +1950,11 @@ async function init() {
 		btn.addEventListener('click', () => navigate('/' + btn.dataset.section));
 	});
 
+	// Lightbox
+	const lightbox = document.getElementById('lightbox');
+	lightbox.addEventListener('click', () => { lightbox.hidden = true; });
+	document.addEventListener('keydown', (e) => { if (e.key === 'Escape') lightbox.hidden = true; });
+
 	// Maintenance menu
 	const maint_toggle = document.getElementById('maint-toggle');
 	const maint_dropdown = document.getElementById('maint-dropdown');
diff --git a/public/index.html b/public/index.html
index 6979e0b..5afd9a3 100644
--- a/public/index.html
+++ b/public/index.html
@@ -25,6 +25,9 @@
 		</div>
 	</header>
 	<main id="main"></main>
+	<div id="lightbox" hidden>
+		<img id="lightbox-img" alt="">
+	</div>
 	<script type="module" src="/app.mjs"></script>
 </body>
 </html>
diff --git a/public/style.css b/public/style.css
index ad9a698..a493cf6 100644
--- a/public/style.css
+++ b/public/style.css
@@ -148,6 +148,31 @@ nav {
 	background: var(--surface-raised);
 }
 
+/* ===== LIGHTBOX ===== */
+
+#lightbox {
+	position: fixed;
+	inset: 0;
+	background: rgba(0,0,0,0.85);
+	display: flex;
+	align-items: center;
+	justify-content: center;
+	z-index: 1000;
+	cursor: zoom-out;
+}
+
+#lightbox[hidden] {
+	display: none;
+}
+
+#lightbox-img {
+	max-width: 90vw;
+	max-height: 90vh;
+	object-fit: contain;
+	border-radius: 3px;
+	box-shadow: 0 8px 40px rgba(0,0,0,0.6);
+}
+
 /* ===== MAIN ===== */
 
 #main {