Show invite reasons

Displays the reason for invitation in the invitation dialog, requiring a
click to reveal the message.

Signed-off-by: Robin Townsend <robin@robin.town>

res/themes/light/css/_light.scss

@@ -325,6 +325,8 @@ $user-tile-hover-bg-color: $header-panel-bg-color;
 // FontSlider colors
 $appearance-tab-border-color: $input-darker-bg-color;
 
+$invite-reason-border-color: $input-darker-bg-color;
+
 // blur amounts for left left panel (only for element theme, used in _mods.scss)
 $roomlist-background-blur-amount: 40px;
 $groupFilterPanel-background-blur-amount: 20px;