fix regression: add zebra effect in list and columns view

Author: jrief

client/scss/_colors.scss

@@ -5,6 +5,7 @@ $focus-visible-box-shadow: rgb(50, 150, 250) 0 0 5px;
 $active-rectangle: var(--accent, rgb(210, 210, 112));
 $body-fg-color: var(--body-fg, #000);
 $body-bg-color: var(--body-bg, #fff);
+$darkened-bg: var(--darkened-bg, #f0f0f0);
 $border-color: var(--border-color, #808080);
 $selected-bg-color: var(--selected-bg, #f0f0f0);
 $selected-row-color: var(--selected-row, #ffffcc);

client/scss/finder-admin.scss

@@ -424,7 +424,7 @@ ul.messagelist {
 			box-sizing: border-box;
 
 			&:nth-child(even):not(.selected) {
-				background-color: $body-bg-color;
+				background-color: $darkened-bg;
 			}
 
 			&:last-child {