chore: Add a minimum spacing for toasts, b=(no-bug), c=common

Author: mr-cheffy

src/zen/common/styles/zen-popup.css

@@ -330,17 +330,18 @@ menuseparator {
 
 #zen-toast-container {
   position: fixed;
-  top: calc(var(--zen-element-separation) * 2);
+  --zen-toast-spacing: max(8px, calc(var(--zen-element-separation) * 2));
+  top: var(--zen-toast-spacing);
   z-index: 1000;
   display: flex;
   align-items: end;
 
   :root:not([zen-right-side='true']) & {
-    right: calc(var(--zen-element-separation) * 2);
+    right: var(--zen-toast-spacing);
   }
 
   :root[zen-right-side='true'] & {
-    left: calc(var(--zen-element-separation) * 2);
+    left: var(--zen-toast-spacing);
   }
 
   & .zen-toast {