Quiet fields: base.css field baseline, --field tokens, 3:1 border-strong, app-wide migration

styles/base.css

@@ -55,6 +55,49 @@ body {
   outline-offset: 2px;
 }
 
+/*
+ * Field baseline (arch 09 §4) — the quiet field: a fill one step off its surface
+ * plus a bottom border only, no box. The fill comes from the contextual --field
+ * token (elevated surfaces set `--field: var(--field-02)` on their container,
+ * the same mechanism as --control-hover-fill); the underline is --border-strong,
+ * which meets 3:1 non-text contrast in both themes. Declared once here at zero
+ * specificity (:where) so modules add only their idiosyncrasies — width, mono
+ * font, padding — never a competing border recipe. Monaco's internal widgets
+ * (find/replace inputs) keep their own styling and are excluded.
+ */
+:where(
+  input:not([type]),
+  input[type='text'],
+  input[type='search'],
+  input[type='number'],
+  input[type='url'],
+  textarea
+):where(:not(.monaco-editor *)) {
+  font: inherit;
+  color: var(--text);
+  background: var(--field);
+  border: none;
+  border-block-end: var(--border-width) solid var(--border-strong);
+  border-radius: var(--radius);
+}
+
+:where(input, textarea)::placeholder {
+  color: var(--text-placeholder);
+}
+
+/* On a field the ring hugs the box — an offset ring reads as a second border
+   where there is no longer a box to anchor it. */
+:where(
+    input:not([type]),
+    input[type='text'],
+    input[type='search'],
+    input[type='number'],
+    input[type='url'],
+    textarea
+  ):where(:not(.monaco-editor *)):focus-visible {
+  outline-offset: -2px;
+}
+
 @media (prefers-reduced-motion: reduce) {
   *,
   *::before,