Many improvements

styles.css

@@ -125,6 +125,63 @@ main {
   font-family: "Iowan Old Style", "Palatino Linotype", "URW Palladio L", serif;
 }
 
+.error-overlay {
+  position: fixed;
+  right: 1rem;
+  bottom: 1rem;
+  z-index: 10000;
+  width: min(42rem, calc(100vw - 2rem));
+  max-height: min(28rem, calc(100vh - 2rem));
+  overflow: auto;
+  border: 1px solid rgba(111, 23, 23, 0.32);
+  border-radius: 8px;
+  background: #fff7f4;
+  box-shadow: 0 18px 60px rgba(59, 20, 20, 0.22);
+  color: #331514;
+}
+
+.error-overlay[hidden] {
+  display: none;
+}
+
+.error-overlay-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 1rem;
+  padding: 0.8rem 1rem;
+  border-bottom: 1px solid rgba(111, 23, 23, 0.18);
+  background: #f6d5ce;
+}
+
+.error-overlay-actions {
+  display: flex;
+  gap: 0.45rem;
+}
+
+.error-overlay button {
+  border: 1px solid rgba(111, 23, 23, 0.28);
+  border-radius: 6px;
+  padding: 0.35rem 0.55rem;
+  background: #fffaf8;
+  color: inherit;
+  font: inherit;
+  cursor: pointer;
+}
+
+.error-overlay pre {
+  margin: 0;
+  border-radius: 0;
+  background: transparent;
+  white-space: pre-wrap;
+}
+
+.error-overlay-copy-buffer {
+  position: fixed;
+  top: -100vh;
+  left: -100vw;
+}
+
 @media (max-width: 900px) {
   .app-shell {
     grid-template-columns: 1fr;
@@ -133,4 +190,4 @@ main {
   #map {
     min-height: 65vh;
   }
-}
+}