Default images and videos to a thumbnail size

First, the “why”:

  1. To save precious screen estate when browsing.
  2. To avoid big embeds disrupting the flow of text / your rhythm of reading.

We can always click on the “enlarge” button to view the original image, or go into Wide Mode by pressing t w to watch videos in a bigger size.


This is built upon ideas from other users such as all the amazing tips in this thread: Set default embedded media (video and image ) size - #6 by theBenForce

This post is noob-oriented — from one noob to fellow noobs😀 — and aims to cover as many use cases as possible.

( This is a tedious solution that separate CSS has to be added for every single case. It wouldn’t be as troublesome if a video-embed class would be added to the iframe element when the {{video }} macro is used, so if someone could volunteer… )

How does this work?

Everything below is supposed to be added in the custom.css file under /logseq in your graph’s folder.

1. Image thumbnails

.asset-container > img {
  max-height: 128px;
  width: auto;

Note: max-height is preferred over height because the latter will stretch out originally short images (for example a screenshot of two lines of text).

2. Small videos in default mode

First the two most common use cases — YouTube and local videos

2.1 YouTube

iframe[id^='youtube-player'] {
/* Add iframe[src*=''] if you use that */
  height: 135px; 
  width: auto;


  • ^= is “starts with”
    in logseq currently only YouTube embeds have the id attribute and they all start with youtube-player followed by random numbers
  • *= is “contains”
    i.e. iframe[src*=''] selects iframe elements (meaning HTML embeds) that contain “” in the src attribute

2.2 Local Videos (updated: I took into consideration that there are 2 ways of embeds!)

For local videos embedded using the macro {{video <local path>}}, the video will be in an iframe. So, using MP4 and MKV as an example, the CSS will be:

iframe[src$='.mkv'] {
  height: 135px;
  width: auto;

Explanation: $= is “ends with” — should be obvious!

For videos added via the native syntax (for org-mode it’s something like [[../assets/video.mp4][label]], for markdown I’m not sure but maybe something like ![](video.mp4) ), you can just use the video element:

video {
  height: 135px;
  width: auto;

2.3 With the above knowledge, especially the bit about how *= works, you can work out the CSS for other streaming sites

Using Vimeo as an example:

iframe[src*='player.vimeo'] {
  height: 135px;
  width: auto;

2.4 Bilibili

(Skip this section if you have no use of it.)
You can use the same pattern for bilibili — iframe[src*='player.bilibili'] — But for the default embed, the timeline controls won’t appear unless it is more than 320p tall and more than 480p wide.
I still use the same size for bilibili because it’s still possible to scrub the timeline in Wide Mode, as screen space is more important to me. But if you find this annoying, say goodbye to the 320px on your monitor.

iframe[src*='player.bilibili'] {
  height: 135px; /* >=320 for timeline to appear */
  width: auto; /* >= 480 for timeline to appear */

2.5 Important tips

You can avoid repetition by stacking selectors, like so

iframe[src$='.mkv'] {
  height: 135px;
  width: auto;

2.6 Common slip-ups

  • Every key-value pair in a {} needs to end with a ; (well except the last pair). If you’re having problems, you might be missing a ; .
  • When you’re stacking selectors, remember to put a comma after each selector!

3. Big videos in Wide Mode

This will give you bigger videos in Wide Mode:

.ls-wide-mode video,
.ls-wide-mode iframe[id^='youtube-player'], 
.ls-wide-mode iframe[src*=''],
.ls-wide-mode iframe[src*='player.vimeo'],
.ls-wide-mode iframe[src$='.mp4'],
.ls-wide-mode iframe[src$='.mkv'] {
  height: 540px; /* half of 1080p */
  width: 100%;

Explanation (assuming you already know about the stacking mentioned above):

  • As with all the other numbers, 540px is just what I use. Use whatever you like!
  • 100% is recommended for width because if you set a fixed number, the video will not adjust accordingly even if your side bar is open and covers the content!

This is the end, guys!

if you don’t need bilibili

The highest resolution for the bilibili embeds is 360p. So instead of a bigger blurry video I chose to save more space —

.ls-wide-mode iframe[src*='player.bilibili'] {
  height: 360px; /* highest resolution available anyway */
  width: 640px; /* 360p/(16/9) */

Very helpful post, thank you.

A question about images in particular:

Is it possible to have this be the default, but also make it easily overridable by dragging the selector?

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I don’t know unfortunately. If there’s a way I’d love to know!
(While testing I found the !important is no longer necessary so I removed it in the original post. Not that it affects anything, though.)

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Updated: I took into consideration that there are 2 ways of embeds for local videos.

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Does it not become default if you put it in your custom.css?

@WQing re Image thumbnail, is it possible to zoom when hovering over the image?