This question has been answered by markh. See the first response.
<link rel="stylesheet" type="text/css" href="[[++assets_url]]css/mycssfile.css" />
Try set site_url in your context settings. The base looks crazy.
I think chrome's element view is just a representation of the domtree.
First, make sure the link tag is in the head section of the template.
Second, the css would normally be in a file in the assets directory (most often in assets/css/), and the file's URL would go in the link tag:
<link rel="stylesheet" type="text/css" href="[[++assets_url]]css/mycssfile.css">
Note that there's no slash after the assets_url tag, because the MODX path and URL settings always end in a slash.
It is possible to put CSS in a resource's content field and reference that resource, but it's rare, and the resource must have a completely empty template (I'm guessing that's your problem). The resource should not have style tags.
Your viewport meta tag, right before the link tag, seems to be missing a quote at the end of the content attribute causing the browser to get confused and probably failing to retrieve the stylesheet.
In your CSS resource you should not use any HTML, so no style tags, as you're trying to trick the browser into thinking it's an actual CSS file, and CSS files don't have style tags.![]()