fix(frontend): reduce system message font size and padding

frontend/src/style.css

@@ -744,12 +744,12 @@ select {
 }
 
 .message-system {
-  font-size: 0.83rem;
+  font-size: 0.7rem;
   color: var(--ink-1);
   background: color-mix(in srgb, var(--brand) 22%, var(--panel-2));
   border: 1px solid color-mix(in srgb, var(--brand) 45%, var(--line));
   border-radius: 0;
-  padding: 0.24rem 0.68rem;
+  padding: 0.2rem 0.5rem;
   animation: messageIn var(--fast);
 }