css: Make all modal buttons half opaque when disabled, instead of grey.

Earlier, the primary modal button always turned grey on being disabled,
while other modal buttons remained as is in light mode, and grey in dark
mode. Now the styling is made consistent across all modal buttons, by
giving them all 50% opacity when disabled.

web/styles/dark_theme.css

@@ -104,11 +104,6 @@
         }
     }
 
-    .modal__btn:disabled {
-        opacity: 1;
-        background-color: hsl(0deg 0% 83% / 50%);
-    }
-
     & table.table-striped thead.table-sticky-headers th {
         background-color: hsl(0deg 0% 0%);
 

web/styles/modal.css

@@ -129,6 +129,7 @@
 
     &:disabled {
         cursor: not-allowed;
+        opacity: 0.5;
     }
 }
 
@@ -151,10 +152,6 @@
     margin-left: 12px;
     background-color: hsl(240deg 96% 68%);
     color: hsl(0deg 0% 100%) !important;
-
-    &:disabled {
-        background-color: hsl(0deg 0% 65%);
-    }
 }
 
 #read_receipts_error,