fix(frontend): readability in both themes

- Token colors wrapped in color-mix so opacity modifiers (bg-surface/90 etc.)
  generate rules; map overlay panels were rendering see-through.
- Light mode: keep white text on saturated fills (primary/danger buttons were
  remapped to navy); map text-gray-200, bg-gray-800/60, border-gray-600.
- Dark mode: lift text-gray-600/700 to gray-500 for contrast.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

drb-frontend/app/globals.css

@@ -67,6 +67,10 @@ html, body {
   font-family: var(--font-mono), ui-monospace, monospace;
 }
 
+/* Dark mode: raw gray-600/700 text sits ~2.4:1 on the near-black page — below
+ * readable. Lift both to gray-500 (~4:1). */
+.dark .text-gray-600, .dark .text-gray-700 { color: #6b7280; }
+
 /* ── Light mode overrides ─────────────────────────────────────────────────── */
 /*
  * The app's components use hardcoded dark-palette Tailwind classes (bg-gray-9xx,
@@ -84,6 +88,7 @@ html:not(.dark) .bg-gray-900\/60    { background-color: rgba(255,255,255,0.85) !
 html:not(.dark) .bg-gray-900\/50    { background-color: rgba(255,255,255,0.75) !important; }
 html:not(.dark) .bg-gray-900\/30    { background-color: rgba(255,255,255,0.50) !important; }
 html:not(.dark) .bg-gray-800        { background-color: #f1f5f9 !important; }
+html:not(.dark) .bg-gray-800\/60    { background-color: rgba(226,232,240,0.70) !important; }
 html:not(.dark) .bg-gray-800\/40    { background-color: rgba(241,245,249,0.60) !important; }
 html:not(.dark) .bg-gray-800\/30    { background-color: rgba(241,245,249,0.50) !important; }
 html:not(.dark) .bg-gray-700        { background-color: #e2e8f0 !important; }
@@ -91,16 +96,25 @@ html:not(.dark) .bg-gray-700        { background-color: #e2e8f0 !important; }
 /* Borders */
 html:not(.dark) .border-gray-800   { border-color: #e2e8f0 !important; }
 html:not(.dark) .border-gray-700   { border-color: #cbd5e1 !important; }
+html:not(.dark) .border-gray-600   { border-color: #94a3b8 !important; }
+html:not(.dark) .border-gray-800\/60 { border-color: #e2e8f0 !important; }
 html:not(.dark) .divide-gray-800 > * + * { border-color: #e2e8f0 !important; }
 
 /* Text */
 html:not(.dark) .text-white        { color: #0f172a !important; }
 html:not(.dark) .text-gray-100     { color: #1e293b !important; }
+html:not(.dark) .text-gray-200     { color: #1e293b !important; }
 html:not(.dark) .text-gray-300     { color: #334155 !important; }
 html:not(.dark) .text-gray-400     { color: #475569 !important; }
 html:not(.dark) .text-gray-500     { color: #64748b !important; }
 html:not(.dark) .text-gray-600     { color: #94a3b8 !important; }
 
+/* …except on saturated fills (primary/danger/success buttons), where the fill
+ * stays dark in both themes — remapping to navy made their labels unreadable. */
+html:not(.dark) .text-white:is(.bg-accent, .bg-sev-major, .bg-sev-moderate,
+  .bg-indigo-500, .bg-indigo-600, .bg-indigo-700, .bg-red-600, .bg-red-700,
+  .bg-green-600, .bg-green-700, .bg-yellow-700, .bg-yellow-800, .bg-gray-600) { color: #ffffff !important; }
+
 /* Hover states */
 html:not(.dark) .hover\:bg-gray-900:hover  { background-color: #f8fafc !important; }
 html:not(.dark) .hover\:bg-gray-900\/50:hover { background-color: rgba(255,255,255,0.75) !important; }

drb-frontend/tailwind.config.ts

@@ -1,5 +1,8 @@
 import type { Config } from "tailwindcss";
 
+const tok = (name: string) =>
+  `color-mix(in srgb, var(--${name}) calc(<alpha-value> * 100%), transparent)`;
+
 const config: Config = {
   content: [
     "./app/**/*.{ts,tsx}",
@@ -15,24 +18,27 @@ const config: Config = {
       // Semantic tokens — defined as CSS custom properties in app/globals.css on
       // :root (light) and .dark (dark). Components must use these names, never a
       // raw gray-9xx, so a theme is one variable block rather than an override sheet.
+      // Wrapped in color-mix so opacity modifiers (bg-surface/90, bg-accent/15)
+      // work — a bare var() hex gives Tailwind nothing to apply alpha to, and the
+      // class silently generates no rule (map overlays rendered see-through).
       colors: {
-        page:        "var(--page)",
+        page:          tok("page"),
-        surface:     "var(--surface)",
+        surface:       tok("surface"),
-        raised:      "var(--raised)",
+        raised:        tok("raised"),
-        line:        "var(--line)",
+        line:          tok("line"),
-        "line-strong": "var(--line-strong)",
+        "line-strong": tok("line-strong"),
         ink: {
-          DEFAULT: "var(--ink)",
+          DEFAULT: tok("ink"),
-          2:       "var(--ink-2)",
+          2:       tok("ink-2"),
-          muted:   "var(--ink-muted)",
+          muted:   tok("ink-muted"),
         },
-        accent:         "var(--accent)",
+        accent:         tok("accent"),
-        "sev-moderate": "var(--sev-moderate)",
+        "sev-moderate": tok("sev-moderate"),
-        "sev-major":    "var(--sev-major)",
+        "sev-major":    tok("sev-major"),
-        "map-bg":    "var(--map-bg)",
+        "map-bg":    tok("map-bg"),
-        "map-block": "var(--map-block)",
+        "map-block": tok("map-block"),
-        "map-road":  "var(--map-road)",
+        "map-road":  tok("map-road"),
-        "map-water": "var(--map-water)",
+        "map-water": tok("map-water"),
       },
       // Marketing/product type scale — used by the (marketing) surface and
       // settings shell so headings read as a deliberate hierarchy rather than