Fix: single banner as grid background, no duplicated images

- Banner is now a single CSS background-image on .brands-grid
  spanning both card columns (left half on FI-NE, right on LACUEOR)
- Cards only have header (above) + spacer + footer (below)
  with semi-transparent solid backgrounds for readability
- Dropdown changes the grid's background-image directly
- Removed per-card <img> elements (was showing image twice)
- Cleaned up orphaned CSS classes

style.css

@@ -382,25 +382,11 @@ body::before {
     gap: 0;
     max-width: 1200px;
     margin: 0 auto;
-}
-
-.brand-card-image-wrap {
-    display: flex;
-    flex-direction: column;
-    height: 100%;
-    width: 100%;
-}
-
-.brand-card-header {
-    flex-shrink: 0;
-    padding: 32px 52px 20px;
-    text-align: center;
-}
-
-.brand-card-footer {
-    flex-shrink: 0;
-    padding: 20px 52px 40px;
-    text-align: center;
+    background-image: url("asset/banner/1.png");
+    background-size: cover;
+    background-position: center;
+    background-repeat: no-repeat;
+    transition: background-image 0.4s ease;
 }
 
 .brand-card {
@@ -413,21 +399,48 @@ body::before {
 }
 
 .brand-card--fine {
-    background: var(--fine-beige);
     border-right: 1px solid var(--border);
 }
 
 .brand-card--lacueor {
+    /* inherits background from grid */
+}
+
+.brand-card-header {
+    flex-shrink: 0;
+    padding: 32px 52px 20px;
+    text-align: center;
+}
+
+.brand-card--fine .brand-card-header {
+    background: var(--fine-beige);
+}
+
+.brand-card--lacueor .brand-card-header {
+    background: var(--lacueor-dark);
+}
+
+.brand-card-spacer {
+    flex: 1;
+    min-height: 280px;
+}
+
+.brand-card-footer {
+    flex-shrink: 0;
+    padding: 20px 52px 40px;
+    text-align: center;
+}
+
+.brand-card--fine .brand-card-footer {
+    background: var(--fine-beige);
+}
+
+.brand-card--lacueor .brand-card-footer {
     background: var(--lacueor-dark);
 }
 
 .brand-card-image {
-    display: block;
-    width: 100%;
-    height: auto;
-    flex-shrink: 0;
-    object-fit: cover;
-    transition: opacity 0.4s ease;
+    display: none;
 }
 
 .brand-card-top-accent {