[Glitch] Add custom closed registrations message to landing page when set

Port SCSS changes from 55a9658ad8 to glitch-soc

app/javascript/flavours/glitch/styles/forms.scss

@@ -475,6 +475,42 @@ code {
       }
     }
   }
+
+  &__overlay-area {
+    position: relative;
+
+    &__overlay {
+      position: absolute;
+      top: 0;
+      left: 0;
+      width: 100%;
+      height: 100%;
+      display: flex;
+      justify-content: center;
+      align-items: center;
+      background: rgba($ui-base-color, 0.65);
+      backdrop-filter: blur(2px);
+      border-radius: 4px;
+
+      &__content {
+        text-align: center;
+
+        &.rich-formatting {
+          &,
+          p {
+            color: $primary-text-color;
+          }
+        }
+      }
+    }
+  }
+}
+
+.block-icon {
+  display: block;
+  margin: 0 auto;
+  margin-bottom: 10px;
+  font-size: 24px;
 }
 
 .flash-message {