diff --git a/packages/cli/src/commands/layout-audit.browser.js b/packages/cli/src/commands/layout-audit.browser.js
index 8693f8a678..058b649dc0 100644
--- a/packages/cli/src/commands/layout-audit.browser.js
+++ b/packages/cli/src/commands/layout-audit.browser.js
@@ -324,12 +324,7 @@
   }
 
   function hasPaint(style) {
-    const backgroundColor = style.backgroundColor || "";
-    const hasBackground =
-      backgroundColor !== "" &&
-      backgroundColor !== "transparent" &&
-      !backgroundColor.endsWith(", 0)") &&
-      backgroundColor !== "rgba(0, 0, 0, 0)";
+    const hasBackground = !isTransparentColor(style.backgroundColor);
     const hasImage = style.backgroundImage && style.backgroundImage !== "none";
     const hasBorder =
       parsePx(style.borderTopWidth) +
@@ -591,10 +586,11 @@
     return element.hasAttribute("data-layout-allow-overlap");
   }
 
+  // Alpha must come from colorAlpha's argument-position parse, never from a
+  // `", 0)"` string suffix: that suffix also matches fully-opaque 3-value rgb()
+  // colours whose blue channel is zero, e.g. pure red/green/yellow.
   function isTransparentColor(color) {
-    return (
-      !color || color === "transparent" || color === "rgba(0, 0, 0, 0)" || color.endsWith(", 0)")
-    );
+    return !color || color === "transparent" || colorAlpha(color) === 0;
   }
 
   function alphaFromParts(parts, index) {
diff --git a/packages/cli/src/commands/layout-audit.browser.test.ts b/packages/cli/src/commands/layout-audit.browser.test.ts
index d65dabba00..3432e040ac 100644
--- a/packages/cli/src/commands/layout-audit.browser.test.ts
+++ b/packages/cli/src/commands/layout-audit.browser.test.ts
@@ -2511,6 +2511,20 @@ describe("layout-audit.browser occlusion", () => {
     expect(occluded?.coveredFraction).toBe(1);
   });
 
+  // PRINFRA-702: `rgb(r, g, 0)` ends in the same `", 0)"` as a transparent
+  // `rgba(..., 0)`, so a string-suffix transparency check silently exempted
+  // opaque red/green/yellow occluders from occlusion entirely.
+  it.each(["rgb(0, 255, 0)", "rgb(255, 0, 0)", "rgb(255, 255, 0)"])(
+    "flags an opaque %s occluder whose blue channel is zero",
+    (backgroundColor) => {
+      const issues = auditOcclusionScene({
+        overlayStyle: { backgroundColor },
+        topmostId: "overlay",
+      });
+      expect(issues.some((issue) => issue.code === "text_occluded")).toBe(true);
+    },
+  );
+
   // #U10: a 2-point hit on the 27-point probe grid (3 rows x 9 columns) is a
   // sliver of edge cover — reports ~0.07 coverage either way, but only GATES
   // (produces a finding) for short atomic labels; ordinary prose survives it.