Desktop polish: seller header contrast, collection image crop, infinite scroll

- seller: only the logo overlaps the cover now; name/handle/stats sit below the
  cover on white (fixes low-contrast name on the gradient)
- collections (home rail, /collections grid, /collection cover): portrait 3/4
  images so full-body figures aren't cropped; detail cover uses object-contain
- MondrianProductList: add IntersectionObserver sentinel for reliable
  infinite scroll on desktop (window-scroll math missed under the footer)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/components/HorizontalCollectionsList.tsx

@@ -131,7 +131,7 @@ const HorizontalCollectionsList = ({
             >
               <div className="flex flex-col gap-3 p-3 bg-WHITE2 rounded-2xl border border-inner-border hover:border-gray-300 transition-all duration-300 hover:shadow-lg h-full">
                 {/* Collection Image */}
-                <div className="relative overflow-hidden rounded-xl w-full h-64 bg-gray-100">
+                <div className="relative overflow-hidden rounded-xl w-full h-64 lg:h-auto lg:aspect-[3/4] bg-gray-100">
                   {collection.coverImageUrl ? (
                     <img
                       src={collection.coverImageUrl}

app/components/MondrianProductList.tsx

@@ -87,6 +87,24 @@ const MondrianProductList = ({
     return () => window.removeEventListener("scroll", handleScroll);
   }, [fetchNextPage, hasNextPage, isFetchingNextPage]);
 
+  // Sentinel-based trigger — more reliable than scroll math on desktop, where
+  // the footer can keep the window-scroll threshold from being reached.
+  const loadMoreRef = useRef<HTMLDivElement>(null);
+  useEffect(() => {
+    const el = loadMoreRef.current;
+    if (!el) return;
+    const observer = new IntersectionObserver(
+      (entries) => {
+        if (entries[0].isIntersecting && hasNextPage && !isFetchingNextPage) {
+          fetchNextPage();
+        }
+      },
+      { rootMargin: "600px" }
+    );
+    observer.observe(el);
+    return () => observer.disconnect();
+  }, [fetchNextPage, hasNextPage, isFetchingNextPage]);
+
   // Memoize expensive filtering operations
   const { oddProducts, evenProducts } = useMemo(() => {
     const odd = products.filter((_, index) => index % 2 === 0);
@@ -177,6 +195,7 @@ const MondrianProductList = ({
               </div>
 
               {hasNextPage && <MondrianSkeleton isMini={true} />}
+              <div ref={loadMoreRef} className="h-px w-full" />
             </>
           )}
         </>

app/routes/collection.$id.tsx

@@ -143,12 +143,12 @@ export default function CollectionDetail() {
         {/* Collection Header */}
         <div className="flex flex-col gap-4 p-4 border-b border-inner-border lg:grid lg:grid-cols-[1.3fr_1fr] lg:gap-8 lg:items-center lg:p-0 lg:py-8 lg:border-0">
           {/* Cover Image */}
-          <div className="relative overflow-hidden rounded-xl w-full mx-auto h-[65vh] bg-gray-100 lg:h-[460px]">
+          <div className="relative overflow-hidden rounded-xl w-full mx-auto h-[65vh] bg-gray-100 lg:h-auto lg:aspect-[3/4] lg:bg-WHITE2">
             {collection.coverImageUrl ? (
               <img
                 src={collection.coverImageUrl}
                 alt={collection.title || "Collection"}
-                className="w-full h-full object-cover"
+                className="w-full h-full object-cover lg:object-contain"
               />
             ) : (
               <div className="w-full h-full flex items-center justify-center bg-WHITE2">

app/routes/collections.tsx

@@ -148,7 +148,7 @@ export default function Collections() {
                 >
                   <div className="flex flex-col gap-3 p-4 bg-WHITE2 rounded-2xl border border-inner-border hover:border-gray-300 transition-all duration-300 hover:shadow-lg">
                     {/* Collection Image - بزرگ */}
-                    <div className="relative overflow-hidden rounded-xl w-full h-48 bg-gray-100">
+                    <div className="relative overflow-hidden rounded-xl w-full h-48 lg:h-auto lg:aspect-[3/4] bg-gray-100">
                       {collection.coverImageUrl ? (
                         <img
                           src={collection.coverImageUrl}

app/routes/seller.$sellerId._index.tsx

@@ -198,8 +198,8 @@ export default function Seller() {
           <div className="relative h-[200px] rounded-[22px] overflow-hidden bg-gradient-to-br from-VITROWN_BLUE to-[#14213d]">
             <div className="absolute inset-0 bg-gradient-to-t from-black/30 to-transparent" />
           </div>
-          <div className="flex items-end gap-6 px-2 -mt-16 relative z-10">
-            <div className="w-[130px] h-[130px] rounded-[28px] border-[5px] border-WHITE shadow-md overflow-hidden bg-WHITE3 shrink-0">
+          <div className="flex items-start gap-6 px-2 mt-4 relative z-10">
+            <div className="w-[130px] h-[130px] -mt-[86px] rounded-[28px] border-[5px] border-WHITE shadow-md overflow-hidden bg-WHITE3 shrink-0">
               {seller?.storeLogo ? (
                 <img
                   src={seller.storeLogo}
@@ -208,7 +208,7 @@ export default function Seller() {
                 />
               ) : null}
             </div>
-            <div className="flex-1 pb-2">
+            <div className="flex-1">
               <h1 className="flex items-center gap-2 text-[28px] font-extrabold">
                 {seller?.storeName}
                 {seller?.isVerified ? (
@@ -246,7 +246,7 @@ export default function Seller() {
                 </div>
               </div>
             </div>
-            <div className="flex gap-2.5 pb-2">
+            <div className="flex gap-2.5">
               <Button
                 variant="dark"
                 size="lg"