# Discourse Horizon Topic Thumbnails

**URL:** <https://meta.discourse.org/t/discourse-horizon-topic-thumbnails/416574>\
**Category:** Theme component\
**Tags:** horizon-theme\
**Created:** [November 4, 2026, 11:17pm UTC](https://meta.discourse.org/t/discourse-horizon-topic-thumbnails/416574 "2026-11-04T23:17:13Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![satonotdead](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/satonotdead/32/447830_2.png) [@satonotdead](https://meta.discourse.org/u/satonotdead)\
**Post date:** [November 4, 2026, 11:17pm UTC](https://meta.discourse.org/t/discourse-horizon-topic-thumbnails/416574/1 "2026-11-04T23:17:13Z")

</div>

| | | |
| --- | --- | --- |
| ℹ | **Summary** | Adds topic thumbnails to Horizon’s high context topic cards |
| 🛠 | **Repository** | [GitHub - criptonautas/discourse-horizon-topic-thumbnails: Topic thumbnails on Horizon's high context topic cards · GitHub](https://github.com/somos-criptonautas/discourse-horizon-topic-thumbnails) |
| ❓ | **Install Guide** | [How to install a theme or theme component](https://meta.discourse.org/t/how-do-i-install-a-theme-or-theme-component/63682) |
| 📖 | **New to Discourse Themes?** | [Beginner’s guide to using Discourse Themes](https://meta.discourse.org/t/beginners-guide-to-using-discourse-themes/91966) |

Install this theme component

Adds thumbnails to Horizon’s high context topic cards without forking or editing Horizon. Disabling or removing the component fully reverts the change.

## Live screenshots

Desktop with the setting `compact last reply` enabled:

 ![horizon-thumbnails-preview-desktop](https://global.discourse-cdn.com/meta/original/4X/5/a/3/5a3b02a79e1adc1ba5487d313bd9516f81a67078.png)  
Mobile with the image on top:

 ![horizon-thumbnails-preview-mobile](https://global.discourse-cdn.com/meta/original/4X/c/6/a/c6a29260489f452540a09357d03f195ef3a0dc3a.png)

### What it does

- Shows the topic’s image on the trailing edge of each card.
- On phones, shows it as a banner above the card.
- Keeps a placeholder for topics with no image, so cards stay uniform.
- Optionally moves the last-reply pill into the footer row to keep cards shorter.
- Loads a size that fits the screen, so a topic list doesn’t download every original image.

> It also works alongside [Horizon AI Gists](https://github.com/criptonautas/discourse-horizon-ai-gists).

### Requirements

- Horizon with high context topic cards enabled
- Site setting `create thumbnails` enabled
- Discourse 2026.5.0 or later

Don’t install it alongside the official Topic List Thumbnails component: it’s not needed, and the two conflict on Horizon’s cards.

### Settings

| Setting | Default | |
| --- | --- | --- |
| `thumbnail_size` | `240` | Thumbnail column width, from 100 to 400 px |
| `mobile_thumbnails` | `true` | Show the banner on phones |
| `placeholder_icon` | `comments` | Icon for topics with no image |
| `placeholder_background` | none | Image behind the placeholder |
| `compact_last_reply` | `true` | Keep cards shorter by moving the last-reply pill |
| `enabled_categories` | empty | Limit thumbnails to these categories; subcategories aren’t included |

### Known limits

- It depends on Horizon’s class and column names. If those change, thumbnails may stop showing or parts of the card may shift until the component is updated.
- Existing topics may show the original image or the placeholder until their sizes are generated in the background.

Tested with a Meta member’s feedback and privately in our commmunity. Bug reports and PRs are welcome.