refactor: remove CSS variables that are now unused

Author: hamirmahal

util/gh-pages/index.html

@@ -594,16 +594,6 @@ <h2 class="panel-title">
             ></path>
         </svg>
         <style>
-            :root {
-                --theme-background-color: black;
-                --theme-foreground-color: white;
-            }
-            @media (prefers-color-scheme: dark) {
-                :root {
-                    --theme-background-color: white;
-                    --theme-foreground-color: black;
-                }
-            }
             .github-corner svg {
                 fill: var(--fg);
                 color: var(--bg);