use 'width' instead of 'aspect-ratio' for browser compatibility

Author: Felix Hennig

src/css/footer.css

@@ -93,8 +93,8 @@ footer.footer {
   align-items: center;
   justify-content: center;
   font-size: 20px;
-  aspect-ratio: 1;
   height: 36px;
+  width: 36px;
   cursor: pointer;
   transition: all 0.3s;
 }