diff --git a/public/logo-stacked-dark.png b/public/logo-stacked-dark.png
new file mode 100644
index 0000000..5a5e425
Binary files /dev/null and b/public/logo-stacked-dark.png differ
diff --git a/src/app/[lang]/layout.tsx b/src/app/[lang]/layout.tsx
index 1c7c74f..d0c01ac 100644
--- a/src/app/[lang]/layout.tsx
+++ b/src/app/[lang]/layout.tsx
@@ -5,6 +5,7 @@ import "../globals.css";
 import SiteHeader from "@/components/site-header";
 import SiteFooter from "@/components/site-footer";
 import Analytics, { AnalyticsNoScript } from "@/components/analytics";
+import { themeScript } from "@/components/theme-toggle";
 import { dirOf, locales, localize, ogLocale } from "@/i18n/config";
 import { mainNav } from "@/i18n/nav";
 import { getUI } from "@/i18n/server";
@@ -51,7 +52,7 @@ export async function generateMetadata(): Promise<Metadata> {
 
 export const viewport: Viewport = {
   themeColor: "#000000",
-  colorScheme: "dark",
+  colorScheme: "dark light",
 };
 
 export default async function RootLayout({ children }: LayoutProps<"/[lang]">) {
@@ -63,6 +64,8 @@ export default async function RootLayout({ children }: LayoutProps<"/[lang]">) {
     closeMenu: t.nav.closeMenu,
     language: t.nav.language,
     logoHome: t.logoHome,
+    lightTheme: t.nav.lightTheme,
+    darkTheme: t.nav.darkTheme,
   };
 
   return (
@@ -71,7 +74,12 @@ export default async function RootLayout({ children }: LayoutProps<"/[lang]">) {
       dir={dirOf(locale)}
       className={`${inter.variable} ${arabic.variable}`}
       data-scroll-behavior="smooth"
+      // The theme script sets data-theme before React hydrates.
+      suppressHydrationWarning
     >
+      <head>
+        <script dangerouslySetInnerHTML={{ __html: themeScript }} />
+      </head>
       <body>
         <AnalyticsNoScript />
         <a href="#main" className="skip-link">
diff --git a/src/app/globals.css b/src/app/globals.css
index 1ec0932..d85a78f 100644
--- a/src/app/globals.css
+++ b/src/app/globals.css
@@ -13,6 +13,13 @@
   --fumo: #8f8f8f;
   --piombo: #666666;
   --argento: #d2d2d2;
+  /* The names keep their roles in both themes: bianco is ink, nero is paper. */
+  --ink-rgb: 255, 255, 255;
+  --paper-rgb: 0, 0, 0;
+  --cap-line: #262626;
+  --panel: #070707;
+  --panel-line: #1c1c1c;
+  color-scheme: dark;
 
   --font-sans: var(--font-inter), "Helvetica Neue", Arial, sans-serif;
 
@@ -28,6 +35,23 @@
   --dir: -1;
 }
 
+/* Light theme, chosen with the header toggle. */
+:root[data-theme="light"] {
+  --bianco: #0a0a0a;
+  --nero: #ffffff;
+  --notte: #f4f4f2;
+  --grafite: #d9d9d6;
+  --fumo: #5c5c5c;
+  --piombo: #808080;
+  --argento: #333333;
+  --ink-rgb: 10, 10, 10;
+  --paper-rgb: 255, 255, 255;
+  --cap-line: #e2e2e2;
+  --panel: #f7f7f5;
+  --panel-line: #e4e4e1;
+  color-scheme: light;
+}
+
 *,
 *::before,
 *::after {
@@ -55,7 +79,7 @@ body {
 
 ::selection {
   background: var(--rosso);
-  color: var(--bianco);
+  color: #fff;
 }
 
 a {
@@ -220,7 +244,7 @@ a {
 .btn-ghost {
   background: transparent;
   color: var(--bianco);
-  border-color: rgba(255, 255, 255, 0.35);
+  border-color: rgba(var(--ink-rgb), 0.35);
 }
 
 .btn-ghost:hover {
@@ -261,7 +285,7 @@ a {
   align-items: center;
   height: 30px;
   padding: 0 14px;
-  border: 1px solid rgba(255, 255, 255, 0.28);
+  border: 1px solid rgba(var(--ink-rgb), 0.28);
   border-radius: 9999px;
   font-size: 10px;
   font-weight: 500;
@@ -303,7 +327,7 @@ a {
 }
 
 .site-header.is-scrolled {
-  background: rgba(0, 0, 0, 0.82);
+  background: rgba(var(--paper-rgb), 0.82);
   backdrop-filter: blur(14px);
   -webkit-backdrop-filter: blur(14px);
   border-color: var(--grafite);
@@ -350,6 +374,7 @@ a {
 }
 
 .logo-type b {
+  white-space: nowrap;
   font-size: 14px;
   font-weight: 600;
   letter-spacing: 0.2em;
@@ -376,7 +401,7 @@ a {
   font-weight: 500;
   letter-spacing: 0.2em;
   text-transform: uppercase;
-  color: rgba(255, 255, 255, 0.78);
+  color: rgba(var(--ink-rgb), 0.78);
   transition: color 0.3s var(--ease);
 }
 
@@ -512,9 +537,9 @@ a {
   inset: 0;
   z-index: -1;
   background:
-    linear-gradient(180deg, rgba(0, 0, 0, 0.55) 0%, transparent 22%),
-    linear-gradient(0deg, #000 4%, rgba(0, 0, 0, 0.6) 34%, transparent 62%),
-    linear-gradient(90deg, rgba(0, 0, 0, 0.7) 0%, transparent 55%);
+    linear-gradient(180deg, rgba(var(--paper-rgb), 0.55) 0%, transparent 22%),
+    linear-gradient(0deg, var(--nero) 4%, rgba(var(--paper-rgb), 0.6) 34%, transparent 62%),
+    linear-gradient(90deg, rgba(var(--paper-rgb), 0.7) 0%, transparent 55%);
   pointer-events: none;
 }
 
@@ -858,13 +883,13 @@ a {
 }
 
 .cap-map line {
-  stroke: #262626;
+  stroke: var(--cap-line);
   stroke-width: 1;
   transition: stroke 0.5s var(--ease);
 }
 
 .cap-map line.on {
-  stroke: rgba(255, 255, 255, 0.6);
+  stroke: rgba(var(--ink-rgb), 0.6);
 }
 
 .cap-map .node {
@@ -882,7 +907,7 @@ a {
 
 .cap-map .core {
   fill: var(--nero);
-  stroke: rgba(255, 255, 255, 0.4);
+  stroke: rgba(var(--ink-rgb), 0.4);
 }
 
 .cap-map text {
@@ -1002,8 +1027,8 @@ a {
   grid-column: 1 / span 6;
   position: relative;
   aspect-ratio: 600 / 412;
-  background: #070707;
-  outline: 1px solid #1c1c1c;
+  background: var(--panel);
+  outline: 1px solid var(--panel-line);
   overflow: hidden;
 }
 
@@ -1071,7 +1096,7 @@ a {
 /* journey viz */
 .viz-journey .path {
   fill: none;
-  stroke: rgba(255, 255, 255, 0.16);
+  stroke: rgba(var(--ink-rgb), 0.16);
   stroke-width: 1;
 }
 
@@ -1099,7 +1124,7 @@ a {
 
 .viz-journey .node {
   fill: var(--nero);
-  stroke: rgba(255, 255, 255, 0.6);
+  stroke: rgba(var(--ink-rgb), 0.6);
 }
 
 .viz-journey .goal {
@@ -1117,11 +1142,11 @@ a {
 /* radar viz */
 .viz-radar .ring {
   fill: none;
-  stroke: rgba(255, 255, 255, 0.12);
+  stroke: rgba(var(--ink-rgb), 0.12);
 }
 
 .viz-radar .axis {
-  stroke: rgba(255, 255, 255, 0.07);
+  stroke: rgba(var(--ink-rgb), 0.07);
 }
 
 .viz-radar .sweep {
@@ -1160,12 +1185,12 @@ a {
 
 /* grid viz */
 .viz-grid .cell {
-  fill: rgba(255, 255, 255, 0.035);
-  stroke: rgba(255, 255, 255, 0.08);
+  fill: rgba(var(--ink-rgb), 0.035);
+  stroke: rgba(var(--ink-rgb), 0.08);
 }
 
 .viz-grid .cell.on {
-  fill: rgba(255, 255, 255, 0.85);
+  fill: rgba(var(--ink-rgb), 0.85);
   stroke: none;
   animation: cell 4.8s var(--ease) infinite;
   animation-delay: var(--t);
@@ -1201,7 +1226,7 @@ a {
 
 .viz-grid .frame {
   fill: none;
-  stroke: rgba(255, 255, 255, 0.5);
+  stroke: rgba(var(--ink-rgb), 0.5);
 }
 
 @media (max-width: 1023px) {
@@ -1290,7 +1315,7 @@ a {
   place-items: center;
   width: 96px;
   height: 96px;
-  border: 1px solid rgba(255, 255, 255, 0.35);
+  border: 1px solid rgba(var(--ink-rgb), 0.35);
   border-radius: 9999px;
   font-size: 9px;
   font-weight: 600;
@@ -1360,7 +1385,7 @@ a {
 }
 
 .journey ol::after {
-  background: linear-gradient(90deg, rgba(255, 255, 255, 0.7), var(--rosso));
+  background: linear-gradient(90deg, rgba(var(--ink-rgb), 0.7), var(--rosso));
   transform: scaleX(0);
   transform-origin: left;
   transition: transform 2.6s var(--ease) 0.2s;
@@ -1434,7 +1459,7 @@ a {
     height: auto;
   }
   .journey ol::after {
-    background: linear-gradient(180deg, rgba(255, 255, 255, 0.7), var(--rosso));
+    background: linear-gradient(180deg, rgba(var(--ink-rgb), 0.7), var(--rosso));
     transform: scaleY(0);
     transform-origin: top;
   }
@@ -1542,7 +1567,7 @@ a {
 }
 
 .gaps .break line {
-  stroke: rgba(255, 255, 255, 0.45);
+  stroke: rgba(var(--ink-rgb), 0.45);
 }
 
 .gaps .break .cut {
@@ -1635,7 +1660,7 @@ a {
   position: absolute;
   inset: 0;
   z-index: -1;
-  background: radial-gradient(ellipse at center, rgba(0, 0, 0, 0.6) 0%, rgba(0, 0, 0, 0.9) 55%, #000 80%);
+  background: radial-gradient(ellipse at center, rgba(var(--paper-rgb), 0.6) 0%, rgba(var(--paper-rgb), 0.9) 55%, var(--nero) 80%);
   pointer-events: none;
 }
 
@@ -1758,7 +1783,7 @@ a {
   line-height: 0.9;
   letter-spacing: -0.05em;
   text-transform: uppercase;
-  color: rgba(255, 255, 255, 0.07);
+  color: rgba(var(--ink-rgb), 0.07);
   white-space: nowrap;
   user-select: none;
 }
@@ -1873,7 +1898,7 @@ a {
 
 .nav-panel-inner {
   padding: 22px 28px 26px;
-  background: rgba(0, 0, 0, 0.94);
+  background: rgba(var(--paper-rgb), 0.94);
   backdrop-filter: blur(14px);
   -webkit-backdrop-filter: blur(14px);
   border: 1px solid var(--grafite);
@@ -2115,7 +2140,7 @@ a {
 }
 
 .link-card:hover {
-  background: rgba(255, 255, 255, 0.03);
+  background: rgba(var(--ink-rgb), 0.03);
 }
 
 .link-card:hover .arrow-link {
@@ -2516,11 +2541,28 @@ a {
   resize: vertical;
 }
 
+/* The message gets a full outline so it reads as a box to type in. */
+.field textarea {
+  min-height: 132px;
+  padding: 12px 14px;
+  border: 1px solid var(--grafite);
+}
+
 .field input:focus,
 .field textarea:focus {
   border-color: var(--rosso);
 }
 
+/* Browser autofill paints its own pale background; keep the field on-theme and readable. */
+.field input:-webkit-autofill,
+.field input:-webkit-autofill:hover,
+.field input:-webkit-autofill:focus {
+  -webkit-text-fill-color: var(--bianco);
+  caret-color: var(--bianco);
+  -webkit-box-shadow: 0 0 0 1000px var(--nero) inset;
+  transition: background-color 9999s;
+}
+
 .field input::placeholder {
   color: var(--piombo);
 }
@@ -2680,6 +2722,64 @@ a {
   color: var(--bianco);
 }
 
+.theme-toggle {
+  display: inline-grid;
+  place-items: center;
+  width: 36px;
+  height: 36px;
+  flex: none;
+  padding: 0;
+  border: 1px solid var(--grafite);
+  border-radius: 50%;
+  background: transparent;
+  color: var(--bianco);
+  cursor: pointer;
+  transition: border-color 0.3s var(--ease);
+}
+
+.theme-toggle:hover {
+  border-color: var(--bianco);
+}
+
+.theme-toggle svg {
+  width: 16px;
+  height: 16px;
+  fill: none;
+  stroke: currentColor;
+  stroke-width: 1.5;
+  stroke-linecap: round;
+}
+
+/* Shows the theme you'd switch to: a sun on dark pages, a moon on light ones. */
+.theme-toggle .moon,
+:root[data-theme="light"] .theme-toggle .sun {
+  display: none;
+}
+
+:root[data-theme="light"] .theme-toggle .moon {
+  display: block;
+}
+
+/* Phones: the languages move into the menu (it carries its own switch) so the logo has room. */
+@media (max-width: 480px) {
+  .site-header .lang-switch {
+    display: none;
+  }
+  .site-header .theme-toggle {
+    margin-inline-start: auto;
+  }
+}
+
+/* The stacked logo's wordmark is white; the light theme swaps in the dark-lettered file. */
+.logo-stacked .on-light,
+:root[data-theme="light"] .logo-stacked .on-dark {
+  display: none;
+}
+
+:root[data-theme="light"] .logo-stacked .on-light {
+  display: block;
+}
+
 .lang-switch [aria-current] {
   color: var(--bianco);
   box-shadow: inset 0 -1px 0 var(--rosso);
@@ -2706,7 +2806,7 @@ a {
   gap: 16px;
   max-width: 340px;
   padding: 14px 18px;
-  border: 1px solid var(--grafite);
+  border: 1px solid var(--piombo);
   transition: border-color 0.3s var(--ease);
 }
 
@@ -2739,7 +2839,7 @@ a {
   width: 24px;
   height: 24px;
   flex: none;
-  border: 1px solid var(--fumo);
+  border: 1.5px solid var(--argento);
   transition:
     border-color 0.3s var(--ease),
     background-color 0.3s var(--ease);
@@ -2754,7 +2854,7 @@ a {
   width: 18px;
   height: 18px;
   fill: none;
-  stroke: var(--bianco);
+  stroke: #fff;
   stroke-width: 1.8;
   stroke-dasharray: 16;
   stroke-dashoffset: 16;
@@ -2810,7 +2910,7 @@ a {
 }
 
 [dir="rtl"] .journey ol::after {
-  background: linear-gradient(270deg, rgba(255, 255, 255, 0.7), var(--rosso));
+  background: linear-gradient(270deg, rgba(var(--ink-rgb), 0.7), var(--rosso));
   transform-origin: right;
 }
 
diff --git a/src/components/content/contact-form.tsx b/src/components/content/contact-form.tsx
index 8983cb7..054d82a 100644
--- a/src/components/content/contact-form.tsx
+++ b/src/components/content/contact-form.tsx
@@ -98,9 +98,13 @@ export default function ContactForm({
           <span>{t.website}</span>
           <input
             name="website"
-            type="url"
+            // Plain text, not type="url": people write "company.com" and shouldn't be made to add https://.
+            type="text"
             inputMode="url"
-            placeholder="https://"
+            autoComplete="url"
+            autoCapitalize="none"
+            spellCheck={false}
+            placeholder="company.com"
             maxLength={300}
             defaultValue={values?.website}
             dir="ltr"
diff --git a/src/components/globe-canvas.tsx b/src/components/globe-canvas.tsx
index bb5045d..5a5e282 100644
--- a/src/components/globe-canvas.tsx
+++ b/src/components/globe-canvas.tsx
@@ -59,6 +59,10 @@ export default function GlobeCanvas({ layout = "hero", className = "hero-canvas"
 
     const reduced = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
 
+    // Dots and lines use the theme's ink colour, re-read whenever the theme changes.
+    const readInk = () => getComputedStyle(document.documentElement).getPropertyValue("--ink-rgb").trim() || "255, 255, 255";
+    let ink = readInk();
+
     // Fibonacci sphere
     const COUNT = 1500;
     const points: Vec[] = [];
@@ -159,15 +163,15 @@ export default function GlobeCanvas({ layout = "hero", className = "hero-canvas"
 
       // soft halo
       const halo = ctx.createRadialGradient(cx, cy, R * 0.7, cx, cy, R * 1.45);
-      halo.addColorStop(0, "rgba(255,255,255,0.045)");
-      halo.addColorStop(1, "rgba(255,255,255,0)");
+      halo.addColorStop(0, `rgba(${ink},0.045)`);
+      halo.addColorStop(1, `rgba(${ink},0)`);
       ctx.fillStyle = halo;
       ctx.fillRect(0, 0, w, h);
 
       // outline
       ctx.beginPath();
       ctx.arc(cx, cy, R * 1.0, 0, Math.PI * 2);
-      ctx.strokeStyle = "rgba(255,255,255,0.08)";
+      ctx.strokeStyle = `rgba(${ink},0.08)`;
       ctx.lineWidth = 1;
       ctx.stroke();
 
@@ -177,7 +181,7 @@ export default function GlobeCanvas({ layout = "hero", className = "hero-canvas"
         const front = p.z > 0;
         const a = front ? 0.18 + p.z * 0.62 : 0.05 + (1 + p.z) * 0.05;
         const size = (front ? 1.15 : 0.8) * p.s;
-        ctx.fillStyle = `rgba(255,255,255,${a.toFixed(3)})`;
+        ctx.fillStyle = `rgba(${ink},${a.toFixed(3)})`;
         ctx.fillRect(p.x - size / 2, p.y - size / 2, size, size);
       }
 
@@ -190,7 +194,7 @@ export default function GlobeCanvas({ layout = "hero", className = "hero-canvas"
           const b = proj[s];
           const vis = (a.z + b.z) / 2;
           if (vis < -0.15) continue;
-          ctx.strokeStyle = `rgba(255,255,255,${(0.08 + Math.max(0, vis) * 0.22).toFixed(3)})`;
+          ctx.strokeStyle = `rgba(${ink},${(0.08 + Math.max(0, vis) * 0.22).toFixed(3)})`;
           ctx.beginPath();
           ctx.moveTo(a.x, a.y);
           ctx.lineTo(b.x, b.y);
@@ -224,7 +228,7 @@ export default function GlobeCanvas({ layout = "hero", className = "hero-canvas"
         ctx.beginPath();
         ctx.arc(p.x, p.y, 3 + pulse * 14, 0, Math.PI * 2);
         ctx.stroke();
-        ctx.fillStyle = `rgba(255,255,255,${(0.4 + p.z * 0.6).toFixed(3)})`;
+        ctx.fillStyle = `rgba(${ink},${(0.4 + p.z * 0.6).toFixed(3)})`;
         ctx.fillRect(p.x - 2.5, p.y - 2.5, 5, 5);
       }
 
@@ -243,6 +247,12 @@ export default function GlobeCanvas({ layout = "hero", className = "hero-canvas"
     });
     ro.observe(canvas);
 
+    const themeObserver = new MutationObserver(() => {
+      ink = readInk();
+      if (reduced) draw(performance.now());
+    });
+    themeObserver.observe(document.documentElement, { attributes: true, attributeFilter: ["data-theme"] });
+
     const io = new IntersectionObserver(([entry]) => {
       const visible = entry.isIntersecting;
       if (visible && !running) {
@@ -263,6 +273,7 @@ export default function GlobeCanvas({ layout = "hero", className = "hero-canvas"
       running = false;
       cancelAnimationFrame(raf);
       ro.disconnect();
+      themeObserver.disconnect();
       io.disconnect();
       window.removeEventListener("pointermove", onMove);
     };
diff --git a/src/components/logo.tsx b/src/components/logo.tsx
index 31cd18e..8c1cef4 100644
--- a/src/components/logo.tsx
+++ b/src/components/logo.tsx
@@ -16,7 +16,8 @@ export default function Logo({ href, label }: { href: string; label: string }) {
 export function LogoStacked({ href, label }: { href: string; label: string }) {
   return (
     <Link href={href} className="logo-stacked" aria-label={label}>
-      <Image src="/logo-stacked.png" alt="AI Growth Technologies" width={480} height={547} />
+      <Image className="on-dark" src="/logo-stacked.png" alt="AI Growth Technologies" width={480} height={547} />
+      <Image className="on-light" src="/logo-stacked-dark.png" alt="AI Growth Technologies" width={480} height={547} />
     </Link>
   );
 }
diff --git a/src/components/product-visuals.tsx b/src/components/product-visuals.tsx
index 8115f30..452fe99 100644
--- a/src/components/product-visuals.tsx
+++ b/src/components/product-visuals.tsx
@@ -25,7 +25,7 @@ function JourneyViz({ labels }: { labels: VisualLabels }) {
   return (
     <svg className="viz viz-journey" viewBox={`0 0 ${W} ${H}`} aria-hidden="true">
       {[180, 280, 380].map((x) => (
-        <line key={x} x1={x} y1={28} x2={x} y2={H - 28} stroke="rgba(255,255,255,0.05)" />
+        <line key={x} x1={x} y1={28} x2={x} y2={H - 28} style={{ stroke: "rgba(var(--ink-rgb), 0.05)" }} />
       ))}
       {sources.map((s, i) => {
         const y = top + i * gap;
@@ -98,7 +98,7 @@ function RadarViz({ labels }: { labels: VisualLabels }) {
       ))}
       <g className="sweep">
         <path d={`M${cx} ${cy} L${cx + sweepR} ${cy} A${sweepR} ${sweepR} 0 0 0 ${ex} ${ey} Z`} fill="url(#sweepGrad)" />
-        <line x1={cx} y1={cy} x2={cx + sweepR} y2={cy} stroke="rgba(255,255,255,0.6)" />
+        <line x1={cx} y1={cy} x2={cx + sweepR} y2={cy} style={{ stroke: "rgba(var(--ink-rgb), 0.6)" }} />
       </g>
       {dots.map((d, i) => {
         const x = cx + Math.cos(rad(d.a)) * d.r;
diff --git a/src/components/site-header.tsx b/src/components/site-header.tsx
index c8d7b4a..f9d25ad 100644
--- a/src/components/site-header.tsx
+++ b/src/components/site-header.tsx
@@ -4,6 +4,7 @@ import Link from "next/link";
 import { usePathname } from "next/navigation";
 import { useEffect, useState } from "react";
 import Logo from "./logo";
+import ThemeToggle from "./theme-toggle";
 import { localeNames, localeShort, locales, localize, splitLocale, type Locale } from "@/i18n/config";
 import type { NavItem } from "@/i18n/nav";
 
@@ -14,6 +15,8 @@ export type HeaderLabels = {
   closeMenu: string;
   language: string;
   logoHome: string;
+  lightTheme: string;
+  darkTheme: string;
 };
 
 function LanguageSwitch({ locale, path, label }: { locale: Locale; path: string; label: string }) {
@@ -120,6 +123,7 @@ export default function SiteHeader({ locale, nav, t }: { locale: Locale; nav: Na
             )}
           </nav>
           <LanguageSwitch locale={locale} path={path} label={t.language} />
+          <ThemeToggle t={t} />
           <Link href={contactHref} className="btn btn-solid header-cta">
             {t.bookCall} <span className="arrow">→</span>
           </Link>
diff --git a/src/components/theme-toggle.tsx b/src/components/theme-toggle.tsx
new file mode 100644
index 0000000..ba3ba96
--- /dev/null
+++ b/src/components/theme-toggle.tsx
@@ -0,0 +1,52 @@
+"use client";
+
+import { useSyncExternalStore } from "react";
+
+export type Theme = "dark" | "light";
+
+// The site is dark by default; a visitor's choice is remembered in localStorage under this key.
+const KEY = "theme";
+
+/** Runs in <head> before the page paints, so a saved light theme never flashes dark first. */
+export const themeScript = `try{if(localStorage.getItem("${KEY}")==="light")document.documentElement.dataset.theme="light"}catch(e){}`;
+
+const read = (): Theme => (document.documentElement.dataset.theme === "light" ? "light" : "dark");
+
+function subscribe(onChange: () => void) {
+  const observer = new MutationObserver(onChange);
+  observer.observe(document.documentElement, { attributes: true, attributeFilter: ["data-theme"] });
+  return () => observer.disconnect();
+}
+
+/** The current theme, kept in sync with <html data-theme>. */
+export function useTheme(): Theme {
+  return useSyncExternalStore(subscribe, read, () => "dark");
+}
+
+export default function ThemeToggle({ t }: { t: { lightTheme: string; darkTheme: string } }) {
+  const theme = useTheme();
+  const label = theme === "dark" ? t.lightTheme : t.darkTheme;
+
+  function toggle() {
+    const next: Theme = theme === "dark" ? "light" : "dark";
+    if (next === "light") document.documentElement.dataset.theme = "light";
+    else delete document.documentElement.dataset.theme;
+    try {
+      localStorage.setItem(KEY, next);
+    } catch {
+      // Storage can be blocked (private mode); the theme still switches for this visit.
+    }
+  }
+
+  return (
+    <button type="button" className="theme-toggle" onClick={toggle} aria-label={label} title={label}>
+      <svg className="sun" viewBox="0 0 24 24" aria-hidden="true">
+        <circle cx="12" cy="12" r="4.2" />
+        <path d="M12 2.5v2.2M12 19.3v2.2M2.5 12h2.2M19.3 12h2.2M5.3 5.3l1.6 1.6M17.1 17.1l1.6 1.6M5.3 18.7l1.6-1.6M17.1 6.9l1.6-1.6" />
+      </svg>
+      <svg className="moon" viewBox="0 0 24 24" aria-hidden="true">
+        <path d="M20 14.6A8.5 8.5 0 0 1 9.4 4a8.5 8.5 0 1 0 10.6 10.6z" />
+      </svg>
+    </button>
+  );
+}
diff --git a/src/content/pages/ar/contact.json b/src/content/pages/ar/contact.json
index ca03623..0857791 100644
--- a/src/content/pages/ar/contact.json
+++ b/src/content/pages/ar/contact.json
@@ -128,7 +128,7 @@
           "subtitle": "مكتب شريك",
           "body": [
             "نقطة تواصل في الولايات المتحدة للشركات في تكساس وخارجها.",
-            "Downtown Houston, TX, USA\nPhone: +1 832-350-0465"
+            "Downtown Houston, TX, USA\nPhone: +1 832-350-0465\nEmail: info@aigrowthtechnologies.com"
           ],
           "list": [],
           "cta": null
@@ -139,7 +139,7 @@
           "subtitle": "مكتب شريك",
           "body": [
             "نقطة تواصل في الولايات المتحدة مقرها جنوب فلوريدا.",
-            "Brickell Avenue, FL, USA\nPhone: +1 954-235-4974"
+            "Brickell Avenue, FL, USA\nPhone: +1 954-235-4974\nEmail: info@aigrowthtechnologies.com"
           ],
           "list": [],
           "cta": null
@@ -150,7 +150,7 @@
           "subtitle": "مكتب شريك",
           "body": [
             "نقطة تواصل في الولايات المتحدة في أحد أبرز أسواق الأعمال في العالم.",
-            "Manhattan Financial District, NY, USA\nPhone: +1 713-289-4577"
+            "Manhattan Financial District, NY, USA\nPhone: +1 713-289-4577\nEmail: info@aigrowthtechnologies.com"
           ],
           "list": [],
           "cta": null
diff --git a/src/content/pages/en/contact.json b/src/content/pages/en/contact.json
index 0a9d120..5d11a12 100644
--- a/src/content/pages/en/contact.json
+++ b/src/content/pages/en/contact.json
@@ -128,7 +128,7 @@
           "subtitle": "Partner Office",
           "body": [
             "A US point of contact for businesses across Texas and beyond.",
-            "Downtown Houston, TX, USA\nPhone: +1 832-350-0465"
+            "Downtown Houston, TX, USA\nPhone: +1 832-350-0465\nEmail: info@aigrowthtechnologies.com"
           ],
           "list": [],
           "cta": null
@@ -139,7 +139,7 @@
           "subtitle": "Partner Office",
           "body": [
             "A US point of contact based in South Florida.",
-            "Brickell Avenue, FL, USA\nPhone: +1 954-235-4974"
+            "Brickell Avenue, FL, USA\nPhone: +1 954-235-4974\nEmail: info@aigrowthtechnologies.com"
           ],
           "list": [],
           "cta": null
@@ -150,7 +150,7 @@
           "subtitle": "Partner Office",
           "body": [
             "A US point of contact in one of the world’s leading business markets.",
-            "Manhattan Financial District, NY, USA\nPhone: +1 713-289-4577"
+            "Manhattan Financial District, NY, USA\nPhone: +1 713-289-4577\nEmail: info@aigrowthtechnologies.com"
           ],
           "list": [],
           "cta": null
diff --git a/src/content/pages/es/contact.json b/src/content/pages/es/contact.json
index b22a6c6..1a2e1d5 100644
--- a/src/content/pages/es/contact.json
+++ b/src/content/pages/es/contact.json
@@ -128,7 +128,7 @@
           "subtitle": "Oficina asociada",
           "body": [
             "Un punto de contacto en EE. UU. para empresas de Texas y más allá.",
-            "Downtown Houston, TX, USA\nPhone: +1 832-350-0465"
+            "Downtown Houston, TX, USA\nPhone: +1 832-350-0465\nEmail: info@aigrowthtechnologies.com"
           ],
           "list": [],
           "cta": null
@@ -139,7 +139,7 @@
           "subtitle": "Oficina asociada",
           "body": [
             "Un punto de contacto en EE. UU. ubicado en el sur de Florida.",
-            "Brickell Avenue, FL, USA\nPhone: +1 954-235-4974"
+            "Brickell Avenue, FL, USA\nPhone: +1 954-235-4974\nEmail: info@aigrowthtechnologies.com"
           ],
           "list": [],
           "cta": null
@@ -150,7 +150,7 @@
           "subtitle": "Oficina asociada",
           "body": [
             "Un punto de contacto en EE. UU. en uno de los mercados de negocios más importantes del mundo.",
-            "Manhattan Financial District, NY, USA\nPhone: +1 713-289-4577"
+            "Manhattan Financial District, NY, USA\nPhone: +1 713-289-4577\nEmail: info@aigrowthtechnologies.com"
           ],
           "list": [],
           "cta": null
diff --git a/src/i18n/ui/ar.ts b/src/i18n/ui/ar.ts
index b6fe733..26e7559 100644
--- a/src/i18n/ui/ar.ts
+++ b/src/i18n/ui/ar.ts
@@ -19,6 +19,8 @@ export const ar: UI = {
     openMenu: "فتح القائمة",
     closeMenu: "إغلاق القائمة",
     language: "اللغة",
+    lightTheme: "التبديل إلى الوضع الفاتح",
+    darkTheme: "التبديل إلى الوضع الداكن",
   },
   bookCall: "احجز مكالمة استراتيجية",
   services: {
diff --git a/src/i18n/ui/en.ts b/src/i18n/ui/en.ts
index 68f5b5d..c968805 100644
--- a/src/i18n/ui/en.ts
+++ b/src/i18n/ui/en.ts
@@ -19,6 +19,8 @@ export const en = {
     openMenu: "Open menu",
     closeMenu: "Close menu",
     language: "Language",
+    lightTheme: "Switch to light theme",
+    darkTheme: "Switch to dark theme",
   },
   bookCall: "Book a Strategy Call",
   services: {
diff --git a/src/i18n/ui/es.ts b/src/i18n/ui/es.ts
index 322f804..562003a 100644
--- a/src/i18n/ui/es.ts
+++ b/src/i18n/ui/es.ts
@@ -19,6 +19,8 @@ export const es: UI = {
     openMenu: "Abrir menú",
     closeMenu: "Cerrar menú",
     language: "Idioma",
+    lightTheme: "Cambiar a tema claro",
+    darkTheme: "Cambiar a tema oscuro",
   },
   bookCall: "Agenda una llamada estratégica",
   services: {