diff --git a/frontend/src/app/globals.css b/frontend/src/app/globals.css
index d523a550..7cca7c46 100644
--- a/frontend/src/app/globals.css
+++ b/frontend/src/app/globals.css
@@ -119,6 +119,11 @@
   --space-24: 96px;
   --composer-reserve: 148px;
   --ease-out: cubic-bezier(.22, 1, .36, 1);
+  /* The personal report's paper surface. Declared here so the dark blocks can
+     override it; see the note on .personal-report-reader. */
+  --report-accent: #85432f;
+  --report-paper: #f8f5ee;
+  --report-rule: #c9c2b7;
   /* Hairlines and sheens that are dark-on-light here and light-on-dark there. */
   --ring-hairline: oklch(0 0 0 / .1);
   --sheen: rgba(255, 255, 255, .54);
@@ -3169,9 +3174,10 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
    scroll boundary because the chat shell intentionally locks html/body.
    ============================================================ */
 .personal-report-reader {
-  --report-accent: #85432f;
-  --report-paper: #f8f5ee;
-  --report-rule: #c9c2b7;
+  /* The report palette lives on :root, not here. A custom property declared on
+     this element wins over :root no matter what a media query says, so keeping
+     it local made the theme override dead: dark mode kept the light paper while
+     --color-ink went light with the theme, leaving white text on white paper. */
   width: 100%;
   height: 100%;
   min-height: 0;
@@ -3309,6 +3315,29 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
 }
 
 @media print {
+  /* Paper is always paper. Without this, printing while the screen is in dark
+     mode kept the light-forced backgrounds below but left every ink light,
+     which prints as a blank page. */
+  :root {
+    color-scheme: light;
+    --color-ink: #1d1d1f;
+    --color-ink-strong: #32322f;
+    --color-ink-secondary: #5f5f59;
+    --color-ink-tertiary: #6a6963;
+    --color-canvas: #fbfaf7;
+    --color-canvas-soft: #f3f2ee;
+    --color-border: #d8d6cf;
+    --color-border-strong: #b8b5ad;
+    --color-action: #85432f;
+    --color-action-hover: #6f3627;
+    --color-focus: #85432f;
+    --color-danger: #9a2f2f;
+    --color-success: #28633e;
+    --color-warning: #b07b22;
+    --report-accent: #85432f;
+    --report-paper: #f8f5ee;
+    --report-rule: #c9c2b7;
+  }
   html, body { width: auto !important; height: auto !important; min-height: 0 !important; overflow: visible !important; background: #fff !important; }
   * { -webkit-print-color-adjust: exact !important; print-color-adjust: exact !important; }
   .personal-report-screen-only { display: none !important; }
diff --git a/frontend/tests/personal-report-theme-contract.test.ts b/frontend/tests/personal-report-theme-contract.test.ts
new file mode 100644
index 00000000..f6a18bb2
--- /dev/null
+++ b/frontend/tests/personal-report-theme-contract.test.ts
@@ -0,0 +1,70 @@
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import test from "node:test";
+
+const globalStyles = readFileSync(new URL("../src/app/globals.css", import.meta.url), "utf8");
+
+const luminance = (hex: string) => {
+  const channel = (value: number) => {
+    const c = value / 255;
+    return c <= 0.03928 ? c / 12.92 : ((c + 0.055) / 1.055) ** 2.4;
+  };
+  const [r, g, b] = [1, 3, 5].map((i) => parseInt(hex.slice(i, i + 2), 16));
+  return 0.2126 * channel(r) + 0.7152 * channel(g) + 0.0722 * channel(b);
+};
+const contrast = (a: string, b: string) => {
+  const [hi, lo] = [luminance(a), luminance(b)].sort((x, y) => y - x);
+  return (hi + 0.05) / (lo + 0.05);
+};
+
+function blockTokens(opener: string): Map<string, string> {
+  const start = globalStyles.indexOf(opener);
+  assert.notEqual(start, -1, `missing block: ${opener}`);
+  const end = globalStyles.indexOf("\n}", start);
+  const body = globalStyles.slice(start, end);
+  return new Map([...body.matchAll(/--([\w-]+)\s*:\s*([^;]+);/g)]
+    .map((hit) => [hit[1], hit[2].trim()]));
+}
+
+test("the report palette is declared on :root, never on the reader element", () => {
+  // A custom property declared on .personal-report-reader wins over :root no
+  // matter what a media query says. Keeping it local made the dark override
+  // dead: the paper stayed light while --color-ink went light with the theme,
+  // which is white text on white paper.
+  const reader = globalStyles.slice(globalStyles.indexOf(".personal-report-reader {"));
+  const readerBody = reader.slice(0, reader.indexOf("\n}"));
+  assert.doesNotMatch(readerBody, /--report-(paper|rule|accent)\s*:/);
+  for (const token of ["report-paper", "report-rule", "report-accent"]) {
+    assert.ok(blockTokens(":root {\n  color-scheme: light;").has(token), `--${token} must live on :root`);
+  }
+});
+
+test("report ink clears AA on report paper in both themes", () => {
+  const light = blockTokens(":root {\n  color-scheme: light;");
+  const dark = blockTokens(':root[data-theme="dark"] {');
+  for (const [name, palette] of [["light", light], ["dark", dark]] as const) {
+    const paper = palette.get("report-paper")!;
+    assert.match(paper, /^#[0-9a-f]{6}$/i);
+    for (const ink of ["color-ink", "color-ink-strong", "color-ink-secondary", "color-ink-tertiary", "report-accent"]) {
+      const value = palette.get(ink)!;
+      const ratio = contrast(value, paper);
+      assert.ok(
+        ratio >= 4.5,
+        `${name}: --${ink} (${value}) on --report-paper (${paper}) is ${ratio.toFixed(2)}:1`,
+      );
+    }
+  }
+});
+
+test("print pins the palette back to light so paper is always paper", () => {
+  // Printing while the screen is dark forced white backgrounds but left every
+  // ink light, which comes out of the printer blank.
+  const print = globalStyles.slice(globalStyles.indexOf("@media print {"));
+  assert.match(print, /:root \{\s*\n\s*color-scheme: light;/);
+  const printRoot = blockTokens("@media print {\n  /* Paper is always paper");
+  for (const token of ["color-ink", "color-ink-strong", "report-paper", "report-accent"]) {
+    assert.ok(printRoot.has(token), `@media print must reset --${token}`);
+  }
+  assert.equal(printRoot.get("color-ink"), "#1d1d1f");
+  assert.equal(printRoot.get("report-paper"), "#f8f5ee");
+});