fix: add min-height to designer-area.has-bg to prevent fields being hidden

Author: shvyac

QSL_card_designer.html

@@ -11,7 +11,7 @@
   .sidebar { background: #fff; padding: 20px; border-radius: 8px; box-shadow: 1px 1px 4px #ddd; min-width: 260px;}
   .designer { background: #fff; flex: 1; position: relative; padding: 20px; border-radius: 8px; box-shadow: 1px 1px 4px #ddd; }
   .designer-area { position: relative; width: 500px; height: 320px; background: #eee; border: 2px dashed #bbb; border-radius: 8px; overflow: hidden; margin: 0 auto; }
-  .designer-area.has-bg { width: auto; height: auto; }
+  .designer-area.has-bg { width: auto; height: auto; min-height: 320px}
   .bg-image-input { margin-bottom: 14px; 
   #designerBg {position: absolute;top:0;left:0;width:100%;height:100%;z-index:0;object-fit:cover;}
   .field { position:absolute; min-width: 48px; min-height: 21px; background: transparent; border:1px solid #888; border-radius:4px; padding:0px; cursor:move; -webkit-user-select: none; user-select: none; box-sizing:border-box; overflow:visible; text-align:center; display:flex; align-items:center; justify-content:center;}