diff --git a/app/templates/common/macros.html b/app/templates/common/macros.html
index 8393f47..d53f58d 100644
--- a/app/templates/common/macros.html
+++ b/app/templates/common/macros.html
@@ -172,7 +172,7 @@
     </div>
   </div>
 </div>
-<div class="post-content">
+<div class="post-content" data-r="collectImages">
   <div class="plank even minimal secondary-bg no-shadow post-info">
     <span>
       {%- if tb_pretext -%}
diff --git a/app/templates/threads/thread.html b/app/templates/threads/thread.html
index 1f35193..9238a81 100644
--- a/app/templates/threads/thread.html
+++ b/app/templates/threads/thread.html
@@ -5,6 +5,7 @@
 {%- block title -%}{{thread.title}}{%- endblock -%}
 {%- block content -%}
 <bitty-8 data-connect="/static/js/bits/bookmark-menu.js"></bitty-8>
+<bitty-8 data-connect="/static/js/bits/thread.js"></bitty-8>
 {%- set td -%}
 <ul class="horizontal">
 <li>Started by <a href="{{url_for('users.user_page', username=started_by.username)}}">{{started_by.get_readable_name()}}</a> in topic <a href="{{url_for('topics.topic_by_id', topic_id=topic.id)}}">{{topic.name}}</a></li>
@@ -84,6 +85,18 @@
   </span>
 </div>
 {{ bookmark_menu() }}
+<dialog closedby="any" class="plank thread-lighbox" data-r="showLightbox closeLightbox">
+  <div class="menu">
+    <button data-s="closeLightbox">Close</button>
+    <a href="" target="_blank" rel="noreferrer noopener" class="linkbutton alt">Open original</a>
+  </div>
+  <img class="lightbox-image" src="https://placehold.co/900x710">
+  <div class="menu">
+    <button data-s="lightboxPrevious">Previous</button>
+    <span data-r="lightboxSetCounter">0/0</span>
+    <button data-s="lightboxNext">Next</button>
+  </div>
+</dialog>
 {%- if is_logged_in() and get_active_user().can_post_to_thread_or_topic(thread) -%}
 <form action="{{url_for('threads.reply', thread_id=thread.id)}}" method="POST" class="plank post-edit-form" data-listen="submit" data-r="clearThreadDraft" data-s="clearThreadDraft">
   <h2 class="info">Reply to "{{thread.title}}"</h2>
diff --git a/data/static/css/style.css b/data/static/css/style.css
index d12f555..0762568 100644
--- a/data/static/css/style.css
+++ b/data/static/css/style.css
@@ -743,6 +743,125 @@ table {
   }
 }
 
+ol.sortable-list {
+  display: flex;
+  gap: var(--base-padding);
+  flex-direction: column;
+  list-style: none;
+  flex-grow: 1;
+  margin: 0;
+  padding-left: 0;
+
+  li {
+    display: flex;
+    gap: var(--big-padding);
+  }
+
+  li.immovable .dragger {
+    cursor: not-allowed;
+  }
+}
+
+.plank.dragger {
+  display: flex;
+  align-items: center;
+  /*background-color: var(--bg-color-tertiary);*/
+  padding: var(--base-padding);
+  cursor: move;
+}
+
+.sortable-item-inner {
+  display: flex;
+  gap: var(--base-padding);
+  flex-grow: 1;
+  flex-direction: column;
+
+  & > * {
+    flex-grow: 1;
+  }
+
+  &.row {
+    flex-direction: row;
+  }
+
+  &:not(.row):not(.full) > * {
+    margin-right: auto;
+  }
+}
+
+.badge-editor-badge-container {
+  display: flex;
+  align-items: baseline;
+  gap: var(--base-padding);
+
+  & > input[type=text], & > input[type=url] {
+    width: 100%;
+  }
+}
+
+.badge-editor-file-picker {
+  display: flex;
+  gap: var(--base-padding);
+  flex-direction: column;
+  align-items: center;
+  min-width: 150px;
+
+  & > input[type=file] {
+    width: 100%;
+
+    &::file-selector-button {
+      display: none;
+    }
+  }
+
+  &.hidden {
+    display: none;
+  }
+}
+
+.badge-editor-badge-select {
+  display: flex;
+  gap: var(--base-padding);
+  flex-direction: column;
+  align-items: center;
+  min-width: 200px;
+  & > select {
+    width: 100%;
+  }
+}
+
+.js-only {
+  display: none;
+}
+
+dialog.plank.thread-lighbox {
+  margin: auto;
+  min-width: 80vw;
+  min-height: 70vh;
+  max-width: 80vw;
+  max-height: 70vh;
+
+  flex-direction: column;
+  justify-content: space-between;
+  align-items: center;
+
+  & > .menu {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    width: 100%;
+  }
+
+  &:open {
+    display: flex;
+  }
+}
+
+.lightbox-image {
+  max-width: 50vw;
+  max-height: 50vh;
+}
+
 /* babycode tags */
 .inline-code {
   background-color: var(--code-bg-color);
@@ -924,97 +1043,6 @@ a.mention {
   }
 }
 
-ol.sortable-list {
-  display: flex;
-  gap: var(--base-padding);
-  flex-direction: column;
-  list-style: none;
-  flex-grow: 1;
-  margin: 0;
-  padding-left: 0;
-
-  li {
-    display: flex;
-    gap: var(--big-padding);
-  }
-
-  li.immovable .dragger {
-    cursor: not-allowed;
-  }
-}
-
-.plank.dragger {
-  display: flex;
-  align-items: center;
-  /*background-color: var(--bg-color-tertiary);*/
-  padding: var(--base-padding);
-  cursor: move;
-}
-
-.sortable-item-inner {
-  display: flex;
-  gap: var(--base-padding);
-  flex-grow: 1;
-  flex-direction: column;
-
-  & > * {
-    flex-grow: 1;
-  }
-
-  &.row {
-    flex-direction: row;
-  }
-
-  &:not(.row):not(.full) > * {
-    margin-right: auto;
-  }
-}
-
-.badge-editor-badge-container {
-  display: flex;
-  align-items: baseline;
-  gap: var(--base-padding);
-
-  & > input[type=text], & > input[type=url] {
-    width: 100%;
-  }
-}
-
-.badge-editor-file-picker {
-  display: flex;
-  gap: var(--base-padding);
-  flex-direction: column;
-  align-items: center;
-  min-width: 150px;
-
-  & > input[type=file] {
-    width: 100%;
-
-    &::file-selector-button {
-      display: none;
-    }
-  }
-
-  &.hidden {
-    display: none;
-  }
-}
-
-.badge-editor-badge-select {
-  display: flex;
-  gap: var(--base-padding);
-  flex-direction: column;
-  align-items: center;
-  min-width: 200px;
-  & > select {
-    width: 100%;
-  }
-}
-
-.js-only {
-  display: none;
-}
-
 @media (max-width: 768px) {
   body {
     margin-left: 0;
@@ -1085,4 +1113,17 @@ ol.sortable-list {
     flex-direction: column;
     align-items: center;
   }
+
+  dialog.plank.thread-lighbox {
+    margin: 0;
+    min-width: 100vw;
+    min-height: 100vh;
+    max-width: unset;
+    max-height: unset;
+  }
+
+  .lightbox-image {
+    max-width: 100%;
+    max-height: 100%;
+  }
 }
diff --git a/data/static/js/bits/thread.js b/data/static/js/bits/thread.js
new file mode 100644
index 0000000..7a6852a
--- /dev/null
+++ b/data/static/js/bits/thread.js
@@ -0,0 +1,64 @@
+export const b = {
+  init: 'activatePostImages',
+}
+
+const POST_IMAGES_SELECTOR = 'img.post-image:not(aside img.post-image)'
+
+let images = [];
+let currentIndex = 0;
+
+export function activatePostImages(_, __, ___) {
+  const images = document.querySelectorAll(POST_IMAGES_SELECTOR);
+  images.forEach(image => {
+    image.style.cursor = 'pointer';
+    image.dataset.s = 'collectImages';
+  });
+}
+
+export function collectImages(_, sender, el) {
+  if (!el.contains(sender)) return;
+  images = Array.from(el.querySelectorAll(POST_IMAGES_SELECTOR));
+  currentIndex = images.indexOf(sender);
+  b.trigger('showLightbox');
+}
+
+export function showLightbox(_, __, el) {
+  const originalImg = images[currentIndex];
+  const lightboxImg = el.querySelector('img');
+  const anchor = el.querySelector('a');
+  anchor.href = originalImg.src;
+  lightboxImg.src = originalImg.src;
+  lightboxImg.alt = originalImg.alt;
+
+  if (!el.open) {
+    el.showModal();
+  }
+
+  b.trigger('lightboxSetCounter');
+}
+
+export function closeLightbox(_, __, el) {
+  el.close();
+}
+
+export function lightboxSetCounter(_, __, el) {
+  el.innerText = `${currentIndex + 1}/${images.length}`;
+}
+
+export function lightboxNext(_, __, ___) {
+  if (images.length == 1) return;
+  currentIndex++;
+  if (currentIndex >= images.length) {
+    currentIndex = 0;
+  }
+  b.trigger('showLightbox');
+}
+
+export function lightboxPrevious(_, __, ___) {
+  if (images.length == 1) return;
+  currentIndex--;
+  if (currentIndex < 0) {
+    currentIndex = images.length - 1;
+  }
+  b.trigger('showLightbox');
+}