diff --git a/src/components/App/App.js b/src/components/App/App.js
index ce0d236..e3150fe 100644
--- a/src/components/App/App.js
+++ b/src/components/App/App.js
@@ -1,10 +1,29 @@
+import React from 'react';
+
 import Game from '../Game';
 import Header from '../Header';
 
+const COLORBLIND_STORAGE_KEY = 'colorblindMode';
+
 function App() {
+  const [isColorblindMode, setIsColorblindMode] = React.useState(() => {
+    return window.localStorage.getItem(COLORBLIND_STORAGE_KEY) === 'true';
+  });
+
+  function toggleColorblindMode() {
+    setIsColorblindMode((prev) => {
+      const next = !prev;
+      window.localStorage.setItem(COLORBLIND_STORAGE_KEY, next);
+      return next;
+    });
+  }
+
   return (
-    <div className="wrapper">
-      <Header />
+    <div className={`wrapper ${isColorblindMode ? 'colorblind-mode' : ''}`}>
+      <Header
+        isColorblindMode={isColorblindMode}
+        toggleColorblindMode={toggleColorblindMode}
+      />
 
       <div className="game-wrapper">
         <Game />
diff --git a/src/components/GuessCells/GuessCells.js b/src/components/GuessCells/GuessCells.js
index 29c99bc..c3b19d4 100644
--- a/src/components/GuessCells/GuessCells.js
+++ b/src/components/GuessCells/GuessCells.js
@@ -13,10 +13,22 @@ function GuessCells({guess, answer}) {
     return `cell ${results[index].status}`
   }
 
+  function statusLabel(index) {
+    if (!results) {
+      return undefined;
+    }
+
+    return results[index].status;
+  }
+
   return (
     <p className="guess">
       {range(5).map((index) => (
-        <span key={index} className={className(index)}>
+        <span
+          key={index}
+          className={className(index)}
+          aria-label={statusLabel(index)}
+        >
           { guess ? guess[index] : undefined}
         </span>
       ))}
diff --git a/src/components/Header/Header.js b/src/components/Header/Header.js
index ce7c934..e6387df 100644
--- a/src/components/Header/Header.js
+++ b/src/components/Header/Header.js
@@ -1,9 +1,18 @@
 import React from 'react';
 
-function Header() {
+function Header({ isColorblindMode, toggleColorblindMode }) {
   return (
     <header>
       <h1>Word Game</h1>
+      <button
+        type="button"
+        className="colorblind-toggle"
+        aria-pressed={isColorblindMode}
+        onClick={toggleColorblindMode}
+        title="Toggle colorblind-friendly mode"
+      >
+        {isColorblindMode ? '👁️ Colorblind: On' : '👁️ Colorblind: Off'}
+      </button>
     </header>
   );
 }
diff --git a/src/styles.css b/src/styles.css
index f54c1cf..9fdac61 100644
--- a/src/styles.css
+++ b/src/styles.css
@@ -17,6 +17,21 @@ html {
   --color-gray-900: hsl(0deg 0% 90%);
 }
 
+/*
+  Colorblind-friendly palette.
+
+  Green/yellow is the hardest combination for deuteranopia and
+  protanopia (red-green colorblindness), the most common forms.
+  We swap to a blue/orange scheme instead, which stays distinguishable
+  across all common types of color vision deficiency (including
+  tritanopia). Tile shapes/symbols are also added below so state never
+  depends on color perception alone.
+*/
+.colorblind-mode {
+  --color-success: hsl(215deg 90% 45%);
+  --color-warning: hsl(30deg 100% 45%);
+}
+
 /*
   Custom styles
 */
@@ -66,10 +81,28 @@ h1 {
   text-align: center;
 }
 
+.colorblind-toggle {
+  align-self: center;
+  margin-right: 16px;
+  padding: 6px 12px;
+  border: 1px solid var(--color-gray-500);
+  border-radius: 4px;
+  font-size: 0.85rem;
+  white-space: nowrap;
+}
+.colorblind-toggle[aria-pressed="true"] {
+  border-color: var(--color-success);
+  color: var(--color-success);
+}
+
 @media (max-width: 25rem) {
   h1 {
     font-size: 1.25rem;
   }
+  .colorblind-toggle {
+    font-size: 0.7rem;
+    padding: 4px 8px;
+  }
 }
 
 .game-wrapper {
@@ -140,6 +173,30 @@ h1 {
   color: white;
 }
 
+/*
+  Shape/symbol cues so tile state doesn't depend on color alone.
+  Only shown in colorblind mode to avoid cluttering the default look.
+*/
+.colorblind-mode .cell.correct::after,
+.colorblind-mode .cell.misplaced::after {
+  content: '';
+  position: absolute;
+  bottom: 4px;
+  right: 4px;
+  width: 10px;
+  height: 10px;
+}
+.colorblind-mode .cell.correct::after {
+  /* Filled circle for correct */
+  border-radius: 50%;
+  background: white;
+}
+.colorblind-mode .cell.misplaced::after {
+  /* Diamond for misplaced */
+  background: white;
+  transform: rotate(45deg);
+}
+
 .guess-input-wrapper {
   display: flex;
   flex-direction: column;