docs: remove white background from images + zoomed images (#5846)

This PR does the following:
1. Replaces all images in the anatomy of Unleash doc with new versions
that don't have text on transparent backgrounds. This makes the images
work on both light and dark backgrounds.
2. Removes the white background from images in the docs. This was only
there to make sure the anatomy images worked in dark mode too.
3. Uses the general docs background color (based on your preferred
theme) when zooming in on images.

website/docusaurus.config.js

@@ -154,7 +154,9 @@ module.exports = {
         imageZoom: {
             // Optional medium-zoom options at
             // https://www.npmjs.com/package/medium-zoom#options
-            options: {},
+            options: {
+                background: 'var(--ifm-background-color)'
+            },
         }
     },
     presets: [

website/src/css/custom.css

@@ -100,9 +100,6 @@ main :is(p, figure) > img:not([src^="https://img.shields.io/" i], [src*="badge.s
     /* round corners to match the rest of the page */
     border-radius: var(--ifm-global-radius);
 
-    /* provide a background in case some images are partly transparent */
-    background: var(--unleash-img-background-color);
-
     /* center in-text images */
     display: block;
     margin: auto;