Hi there
May be this will be a stupid question, but… I can’t find out any potential solution to my problem. I rather new to grav, creating a simple site, and I found this cms fantastic. but…
I want to add an iframe in a simple page. So I try, as I read it in another post, to insert my html code in the .md.
The result is just a render text with “<iframe…” . I thought markdown was simply accepting html tags.
I went in the system config, markdown is set to true, markdown_extra also (btw I don’t know what it means). I parsed grav admin to ensure everything was ok, it seems too.
Other markdown styles are working like ## or ** and so on.
If anyone could give an idea, it would be great !
thanks a lot
OleVik
#2
Markdown in general accepts all HTML-tags, but the iFrame-tag and a few others are disabled by default because they pose a security risk. You can customize this in system.yaml.
Well How could could I missed it ! thanks a lot for answering.
But… I must be missing something else.
I remove the tag from xss_dangeroustag in user/config/security.yaml
I also tried to set dangerous_tags to false
I cleared cache (wich also touch the new security file)
And I still get an iframe text 
so what do I do wrong again ?
@Francois, Markdown is not being processed when embedded inside an HTML block element.
I added the following snippet (showing an OpenStreetMap) to a Markdown file using vscode. I made no changes to security.yaml.
<div>
<iframe id="inlineFrameExample"
title="Inline Frame Example"
width="300"
height="200"
src="https://www.openstreetmap.org/export/embed.html?bbox=-0.004017949104309083%2C51.47612752641776%2C0.00030577182769775396%2C51.478569861898606&layer=mapnik">
</iframe>
</div>

Note: I did not try adding the snippet from withing Admin plugin.
@pamtbaau @OleVik so kind to answer
but no
stills not working… here is what I get.
Editing or not security.yaml going to the same result, there must be something stupidly wrong in my config. Is there any special command to reload part of the cms ?
@Francois, I ran my test (again) on a fresh Grav 1.6.26 installation and it worked without any changes to Grav, except adding the snippet into ‘/pages/02.typography/default.md’ using vscode.
Would you mind downloading a fresh copy of Grav 1.6.26 and try again? If that is working you can apply the changes of your original site into the new one, one by one.
@Francois, Copying entire /user folder might be too much, because it will be very likely the issue is somewhere in that folder…
My approach would be:
- Start with fresh install
- Copy from original site folders/files from low probable impact to high and check after each step.
- Create test page with working <iframe>
- Copy
/pages folder. Is <iframe> in copied page working?
If not, take a look at its frontmatter.
- Install fresh theme
- Install fresh plugins one by one
- Copy theme config file
- Copy plugin config file
- Copy site.yaml into
/config
- Copy system.yaml into
/config
- …
Please feed back to the community the cause of the issue.
Yes, found it, and it was a little stupid… from me !
in user/config/system I had place :
markdown:
escape_markup: true
this result in removing capabilities to insert simple tag as they are escaped 
I set it to false and everything is good.
again, thanks a lot !
@Francois, Smart cookie… 
No need to set it to false, just delete it because false is the default. See ‘/system/config/system.yaml’:
markdown:
...
escape_markup: false # Escape markup tags into entities
I do not master everything yet 