Add small UI tweak to the inline color preview square (#33655)

Follow-up to https://github.com/zed-industries/zed/pull/33605 so it is
just a bit more subtle and smaller.

Release Notes:

- N/A

crates/editor/src/display_map/inlay_map.rs

@@ -344,16 +344,14 @@ impl<'a> Iterator for InlayChunks<'a> {
                                 id: ChunkRendererId::Inlay(inlay.id),
                                 render: Arc::new(move |cx| {
                                     div()
-                                        .w_4()
-                                        .h_4()
                                         .relative()
+                                        .size_3p5()
                                         .child(
                                             div()
                                                 .absolute()
                                                 .right_1()
-                                                .w_3p5()
+                                                .size_3()
-                                                .h_3p5()
+                                                .border_1()
-                                                .border_2()
                                                 .border_color(cx.theme().colors().border)
                                                 .bg(color),
                                         )