Release v2.16.5: fix slide animation preview scaling

src/web/public/css/theme-custom.css

@@ -2489,18 +2489,25 @@ html[data-bs-theme='dark'] .template-field-card .tox .tox-collection {
 }
 
 .slide-animation-preview-panel {
+  container-type: size;
   min-width: 0;
+  min-height: 0;
   display: flex;
-  flex-direction: column;
   align-items: center;
+  justify-content: center;
 }
 
 #slide-animation-preview {
   width: 100%;
+  height: 100%;
+  display: flex;
+  align-items: center;
+  justify-content: center;
 }
 
 #slide-animation-preview .slide-preview-stage {
-  width: 100%;
+  width: min(100%, calc(100cqh * var(--slide-layout-ratio, 1.777778)));
+  flex-shrink: 0;
 }
 
 .slide-animation-preview-panel [data-slide-animation-preview][aria-pressed="true"] {
@@ -2514,6 +2521,10 @@ html[data-bs-theme='dark'] .template-field-card .tox .tox-collection {
     grid-template-columns: minmax(0, 1fr);
   }
 
+  .slide-animation-preview-panel {
+    height: min(55dvh, 32rem);
+  }
+
   .slide-animation-controls {
     overflow: visible;
   }