fix: update sub-products in footer

static/css/main.css

@@ -1263,7 +1263,7 @@ a.citation-count-badge:hover {
 
 .article-citation-item {
   display: flex;
-  align-items: baseline;
+  align-items: flex-start;
   gap: 0.5rem;
   font-size: 0.8rem;
   color: var(--text-secondary);
@@ -1284,16 +1284,64 @@ a.citation-count-badge:hover {
   flex: 1;
 }
 
-.citation-link {
+.citation-actions {
   flex-shrink: 0;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 0.65rem;
+}
+
+.citation-link,
+.citation-copy {
   color: var(--accent-blue-light);
   opacity: 0.75;
   transition: opacity 0.2s;
   display: flex;
   align-items: center;
+  justify-content: center;
 }
 
-.citation-link:hover {
+.citation-copy {
+  position: relative;
+  padding: 0;
+  border: none;
+  background: none;
+  cursor: pointer;
+  font: inherit;
+}
+
+.citation-link:hover,
+.citation-copy:hover {
+  opacity: 1;
+}
+
+.citation-copy-feedback {
+  position: absolute;
+  left: 50%;
+  top: calc(100% + 0.2rem);
+  transform: translateX(-50%);
+  font-size: 0.62rem;
+  font-weight: 600;
+  letter-spacing: 0.02em;
+  color: var(--accent-blue-light);
+  white-space: nowrap;
+  pointer-events: none;
+}
+
+.citation-copy-icon-done {
+  display: none;
+}
+
+.citation-copy.is-copied .citation-copy-icon {
+  display: none;
+}
+
+.citation-copy.is-copied .citation-copy-icon-done {
+  display: flex;
+}
+
+.citation-copy.is-copied {
   opacity: 1;
 }