Note that you can open such a SVG image with a chrome:// URI in a Firefox tab and save this image in the usual way.

• chrome://browser/skin/places/bookmarksToolbar.svg

Fill only work for an SVG image and not for the favicon a website supplies. Best is to place custom images in the chrome folder and only specify the file name (no path). You can open the image in a tab to get the correct file:// URI.

You probably have to edit the SVG file and hard code the color values in the file to make Firefox use the colors.

• fill="context-fill" => fill="blue"
• https://searchfox.org/mozilla-release/source/browser/themes/shared/places/bookmarksToolbar.svg

Hi Norbert, there are restrictions on disk access from web pages, scripts, and CSS files. If I understand what you are trying to do, it works best to use the chrome folder as your root. Meaning:

• [profile folder]\chrome\userChrome.css
• [profile folder]\chrome\bookmarksToolbar.svg

In that case, the relative URL is:

list-style-image: url("bookmarksToolbar.svg") !important;

Or if you don't want to see as much clutter:

• [profile folder]\chrome\userChrome.css
• [profile folder]\chrome\images\bookmarksToolbar.svg

In that case:

list-style-image: url("images/bookmarksToolbar.svg") !important;

Note that you can also use a data URI with the preferred fill color directly coded..

list-style-image: url("data:image/svg+xml,<svg width='16' height='16' viewBox='0 0 16 16' fill='blue' fill-opacity='context-fill-opacity' xmlns='http://www.w3.org/2000/svg'>
  <path fill-opacity='.15' d='M15,14H1c-0.6,0-1-0.4-1-1V3c0-0.5,0.4-1,1-1h14c0.6,0,1,0.5,1,1v10C16,13.6,15.6,14,15,14z'/>
  <path d='M8.4,4.2l1,2.1l2.3,0.3c0.3,0,0.5,0.4,0.2,0.7l-1.7,1.7l0.4,2.4c0.1,0.3-0.3,0.6-0.6,0.4L8,10.8L6,12 c-0.3,0.1-0.6-0.1-0.6-0.4l0.4-2.4L4.1,7.4C3.9,7.2,4,6.8,4.3,6.7l2.3-0.3l1-2.1C7.8,3.9,8.2,3.9,8.4,4.2z'/>
  <path d='M15,2H1C0.5,2,0,2.5,0,3v10c0,0.5,0.5,1,1,1h14c0.5,0,1-0.5,1-1V3C16,2.5,15.5,2,15,2z M15,12.5 c0,0.3-0.2,0.5-0.5,0.5h-13C1.2,13,1,12.8,1,12.5v-9C1,3.2,1.2,3,1.5,3h13C14.8,3,15,3.2,15,3.5V12.5z'/>
</svg>") !important;

I found a solution on r/FirefoxCSS: by default, Firefox does not apply fill to SVG's loaded from an external source. I'm not sure why this is restricted, but there might be some privacy/security reason for it. That said, if you really prefer a physical file over a data URI (see cor-el's previous reply), this is where you toggle a preference to enable it:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

(2) In the search box in the page, type or paste svg.context-properties.content.enabled and pause while the list is filtered

(3) Double-click the preference to switch the value from false to true

More info on about:config: Configuration Editor for Firefox.

Ref. https://www.reddit.com/r/FirefoxCSS/comments/ggmwkh/how_to_change_the_color_of_liststyleimage_urlsvg/fq4ou2g/

How do you stop #'s from being replaced by numbers??

/* Colored folders for Bookmark Menus. */
/* Standard folder -- on Toolbar and Menus */
#PlacesToolbarItems toolbarbutton[container="true"]:not([query="true"]) .toolbarbutton-icon,
:-moz-any(
#PlacesToolbarItems,
#PlacesChevronPopup,
#BMB_bookmarksPopup,

#bookmarksMenu,
s/b
/*#bookmarksMenu,

thanks Norbert

Hi Norbert, you can surround code with the preformatting tags -- <pre> and </pre> -- to avoid having it interpreted as wiki coding.