fixes

- apply fixed height for footer buttons over app
- add floating cart button in cart page in desktop size

src/pages/split-bill/page.tsx

@@ -120,7 +120,7 @@ export default function SplitBillPage() {
           position: "fixed",
           bottom: 0,
           left: 0,
-          height: "10vh",
+          height: "80px",
           display: "flex",
           flexDirection: "row",
           justifyContent: "space-around",