fix(ui): center float QR titles and repair UC VIP layout

assets/css/frontend/floating-buttons.css

@@ -176,6 +176,7 @@
     font-size: 13px;
     line-height: 1.6;
     color: var(--color-ink-3);
+    text-align: center;
 }
 
 .float-btn-qrcode {
@@ -193,8 +194,32 @@
 .float-right .service-qq .hover-show-con,
 .float-right .qrcode-btn .hover-show-con {
     padding: 14px;
+    text-align: center;
 }
 
+/* Page QR hover card: keep title/caption centered under the code */
+.float-right .qrcode-btn .hover-show-con {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+}
+
+.float-right .qrcode-btn .hover-show-con p {
+    width: 100%;
+    text-align: center;
+    margin-top: 2px;
+}
+
+.float-right .qrcode-btn .hover-show-con .float-btn-qrcode__title {
+    width: 100%;
+    text-align: center;
+    margin: 2px 0 0;
+    font-size: 13px;
+    line-height: 1.6;
+    color: var(--color-ink-3);
+}
+
+
 .float-right .service-wechat .hover-show-con img,
 .float-right .service-qq .hover-show-con img {
     margin: 0 auto;