[style](trx-frontend): inset aprs overlay from edges

Offset the APRS overlay slightly from the waterfall edges so it reads
as a hovering strip and leaves the waterfall visible at the sides.

Co-authored-by: OpenAI Codex <codex@openai.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css

@@ -621,8 +621,8 @@ small { color: var(--text-muted); }
   display: none;
   position: absolute;
   top: 50%;
-  left: 0;
-  right: 0;
+  left: 0.45rem;
+  right: 0.45rem;
   width: auto;
   max-width: none;
   transform: translateY(-50%);