dark-mode: decrease brightness of the ruler in the sidebar

It would stick out too much in dark mode otherwise.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

assets/sass/dark-mode.css

@@ -88,6 +88,10 @@
                 color: $font-color;
             }
 
+            hr.sidebar {
+                filter: brightness(0.5);
+            }
+
             #documentation #main div.verseblock pre.content {
                 color: var(--light-font-color);
                 background-color: #5e5951;