CSS for individual tables in a post

Is it possible to style tables in a post individually?
Discourse removes all styling elements from HTML in a post.

Can you share a screenshot of what you want to do? In discourse you can do pretty much anything you want, but it gets harder the more crazy the idea is

I simply want some tables to have a fixed layout, and some auto layout.
I’m referring to tables created with Markdown, BBCode or HTML in composer.

If you can’t target them by id or class, by position? eg. instead of main-st -> smith, main-st -> second-house

What I generally do is go up the DOM until I find an ancestor element with an id, or in lieu of that a few elements with classes, and then go to the child element I want to target. If need be, a “first”, “last” or “nth” pseudo-class should do the job.

I think you mean modifying CSS from the admin panel.
What I’m asking is formatting in the composer window.

You will need to write a plugin that exposes the classes you want to allow users to use to format their tables. Once you do that, they can apply the classes to their posts.


If you’re on a recent version of Discourse - as this is a recent change - you can also use data-theme attributes.

For example:

<div data-theme-table="fixed">
				<th>Col A</th>
				<th>Col B</th>
				<th>Col C</th>

Or with markdown

<div data-theme-table="fixed">

| Col A | Col B | Col C|
| A1 | B1 | C1 |


Would look like this:

Col A Col B Col C
A1 B1 C1

No difference visually - but can be targeted with CSS like this:

[data-theme-table="fixed"] table {
    background: red;

The result is a red background for tables inside divs with the attribute data-theme-table="fixed" but no effect on other tables.


So all you need to do is define the CSS once and then use the attributes in posts where you want the styles to apply.


This is exactly what I was looking for. Thank you @Johani


looking at white-lister.js.es6, I notice:

  'div[data-*]', /* This may seem a bit much but polls does
                    it anyway and this is needed for themes,
                    special code in sanitizer handles data-*
                    nothing exists for data-theme-* and we
                    don't want to slow sanitize for this case

does it mean that div[data-theme-*] is no longer required and we can simply use div[data-*] (e.g. div[data-table-layout])?

Yes, but I’d say to stick with the -theme- prefix for stuff that’s actually handled by a theme.


Yes, you’re correct @BlackKnob, you can use div[data-*] like div[data-table-layout] and it would have the same effect.

However, like @riking said earlier, you’re much better off sticking with div[data-theme-*] since there might be some work in the future to narrow down whitelisted attributes to div[data-theme-*]. When that happens, all of your posts with div[data-*] would need to be updated accordingly.

That’s why using div[data-theme-*] is recommended here, so that you can stay futureproof.


Where do I put the CSS to target the named div I’ve wrapped around the table?
Do I need to create and install a custom theme to be able to use this method of table styling?

Welcome back @kaefert :wave:

Yes, I would recommend that you do that.

  1. go to admin/customize/themes
  2. click Install
  3. select Create New
  4. give it a name and set the type to component
  5. add your CSS
  6. add the component to your active themes by clicking on Add all themes next to the Include_component_on_these_themes setting on the component page.