diff --git a/res/themes/light-custom/css/_custom.scss b/res/themes/light-custom/css/_custom.scss
index b830e86e02..6bb46e8a67 100644
--- a/res/themes/light-custom/css/_custom.scss
+++ b/res/themes/light-custom/css/_custom.scss
@@ -124,15 +124,15 @@ $pinned-unread-color: var(--warning-color);
 $warning-color: var(--warning-color);
 $button-danger-disabled-bg-color: var(--warning-color-50pct); // still needs alpha at 0.5
 //
-// --username colors
-$username-variant1-color: var(--username-colors_1, $username-variant1-color);
-$username-variant2-color: var(--username-colors_2, $username-variant2-color);
-$username-variant3-color: var(--username-colors_3, $username-variant3-color);
-$username-variant4-color: var(--username-colors_4, $username-variant4-color);
-$username-variant5-color: var(--username-colors_5, $username-variant5-color);
-$username-variant6-color: var(--username-colors_6, $username-variant6-color);
-$username-variant7-color: var(--username-colors_7, $username-variant7-color);
-$username-variant8-color: var(--username-colors_8, $username-variant8-color);
+// --username colors (which use a 0-based index)
+$username-variant1-color: var(--username-colors_0, $username-variant1-color);
+$username-variant2-color: var(--username-colors_1, $username-variant2-color);
+$username-variant3-color: var(--username-colors_2, $username-variant3-color);
+$username-variant4-color: var(--username-colors_3, $username-variant4-color);
+$username-variant5-color: var(--username-colors_4, $username-variant5-color);
+$username-variant6-color: var(--username-colors_5, $username-variant6-color);
+$username-variant7-color: var(--username-colors_6, $username-variant7-color);
+$username-variant8-color: var(--username-colors_7, $username-variant8-color);
 //
 // --timeline-highlights-color
 $event-selected-color: var(--timeline-highlights-color);