Fix dark mode CSS: force off-white text on all interactive surfaces, leave bg to Gradio

The broad selector at line 306 already set all inputs/textareas/dropdowns to
off-white text. Two later selectors with their own !important were reversing
it back to dark ink (#1A1A1A):

- .ask-block textarea: color: var(--ink) -> var(--light-ink)
- Domain dropdown: color: var(--ink) + forced white bg -> var(--light-ink), no bg

Also removed the forced white bg from the input border rule — Gradio's dark
mode wins for backgrounds, so forcing white there was either dead or could
create white-on-white if it ever started winning.

app.py

@@ -382,15 +382,14 @@ body, .gradio-container { background: var(--bg) !important; color: var(--ink) !i
     font-weight: 600 !important;
 }
 
-/* Domain dropdown text — keep dark for readability */
+/* Domain dropdown text — off-white on whatever bg Gradio renders */
 .gradio-container .domain-dropdown,
 .gradio-container .domain-dropdown input,
 .gradio-container .domain-dropdown .wrap,
 .gradio-container .domain-dropdown .single-select,
 .gradio-container .domain-dropdown .selected-item {
-    color: var(--ink) !important;
-    -webkit-text-fill-color: var(--ink) !important;
-    background: var(--surface) !important;
+    color: var(--light-ink) !important;
+    -webkit-text-fill-color: var(--light-ink) !important;
 }
 
 /* Result summary: pure black, prominent */
@@ -414,7 +413,8 @@ body, .gradio-container { background: var(--bg) !important; color: var(--ink) !i
     border-radius: var(--radius) !important;
 }
 
-/* Hairline borders, never thick rules */
+/* Hairline borders, never thick rules.
+   Background left to Gradio — dark mode renders dark surfaces naturally. */
 .gradio-container .gr-input,
 .gradio-container .gr-textbox,
 .gradio-container .gr-textbox textarea,
@@ -423,7 +423,6 @@ body, .gradio-container { background: var(--bg) !important; color: var(--ink) !i
 .gradio-container .gr-code,
 .gradio-container .gr-button {
     border: 1px solid var(--hairline) !important;
-    background: var(--surface) !important;
 }
 
 /* ── Typography ────────────────────────────────────────────────────── */
@@ -516,7 +515,7 @@ body, .gr-markdown, .gr-input, .gr-button {
     font-size: 1.125rem !important;
     padding: 0.875rem 1rem !important;
     min-height: 3.5rem !important;
-    color: var(--ink) !important;
+    color: var(--light-ink) !important;
 }
 .primary-cta {
     background: var(--ink) !important;