diff --git a/src/components/Lightbox.astro b/src/components/Lightbox.astro
new file mode 100644
index 0000000..6f53c9f
--- /dev/null
+++ b/src/components/Lightbox.astro
@@ -0,0 +1,233 @@
+---
+interface Props {
+  src: string;
+  alt: string;
+  width: number;
+  height: number;
+  loading?: 'eager' | 'lazy';
+  caption?: string;
+  triggerClass?: string;
+  imgClass?: string;
+}
+
+const {
+  src,
+  alt,
+  width,
+  height,
+  loading = 'lazy',
+  caption,
+  triggerClass = '',
+  imgClass = 'block w-full h-auto',
+} = Astro.props;
+
+// Unique per-instance id so multiple lightboxes on a page do not collide.
+const dialogId = `lb-${Math.random().toString(36).slice(2, 10)}`;
+---
+<button
+  type="button"
+  class={`lightbox-trigger group ${triggerClass}`.trim()}
+  data-lightbox-open={dialogId}
+  aria-label={`Enlarge: ${alt}`}
+>
+  <img
+    src={src}
+    alt={alt}
+    width={width}
+    height={height}
+    loading={loading}
+    decoding="async"
+    class={imgClass}
+  />
+  <span aria-hidden="true" class="lightbox-zoom-badge">
+    <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+      <circle cx="11" cy="11" r="7.5"/>
+      <path d="m20 20-3.5-3.5"/>
+      <line x1="11" y1="8" x2="11" y2="14"/>
+      <line x1="8" y1="11" x2="14" y2="11"/>
+    </svg>
+  </span>
+</button>
+
+<dialog id={dialogId} class="lightbox-dialog" aria-modal="true" aria-labelledby={`${dialogId}-title`}>
+  <h2 id={`${dialogId}-title`} class="sr-only">{alt}</h2>
+  <form method="dialog" class="lightbox-close-form">
+    <button type="submit" class="lightbox-close" aria-label="Close">
+      <svg width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.2" stroke-linecap="round" stroke-linejoin="round">
+        <path d="M18 6 6 18"/>
+        <path d="m6 6 12 12"/>
+      </svg>
+    </button>
+  </form>
+  <img src={src} alt={alt} class="lightbox-image" />
+  {caption && <p class="lightbox-caption">{caption}</p>}
+</dialog>
+
+<style>
+  /* Trigger: reset native button chrome, keep block layout matching the old <img>. */
+  .lightbox-trigger {
+    all: unset;
+    display: block;
+    position: relative;
+    cursor: zoom-in;
+    width: 100%;
+  }
+  .lightbox-trigger:focus-visible {
+    outline: 2px solid #f0b429;
+    outline-offset: 4px;
+    border-radius: 0.5rem;
+  }
+
+  /* Zoom pill (fades in on hover / keyboard focus) */
+  .lightbox-zoom-badge {
+    position: absolute;
+    top: 0.85rem;
+    right: 0.85rem;
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    width: 2.25rem;
+    height: 2.25rem;
+    border-radius: 9999px;
+    background: rgba(240, 180, 41, 0.92);
+    color: #060a13;
+    opacity: 0;
+    transform: translateY(-3px);
+    transition: opacity 180ms ease-out, transform 180ms ease-out;
+    pointer-events: none;
+    box-shadow: 0 4px 12px -4px rgba(0, 0, 0, 0.5);
+  }
+  .lightbox-trigger:hover .lightbox-zoom-badge,
+  .lightbox-trigger:focus-visible .lightbox-zoom-badge {
+    opacity: 1;
+    transform: translateY(0);
+  }
+
+  /* Dialog */
+  .lightbox-dialog {
+    padding: 0;
+    margin: auto;
+    width: min(98vw, 1800px);
+    height: min(96vh, 1200px);
+    background: #060a13;
+    color: #e8eaed;
+    border: 1px solid rgba(240, 180, 41, 0.25);
+    border-radius: 0.75rem;
+    overflow: hidden;
+    box-shadow: 0 40px 100px -30px rgba(0, 0, 0, 0.8);
+  }
+  .lightbox-dialog::backdrop {
+    background: rgba(6, 10, 19, 0.82);
+    backdrop-filter: blur(6px);
+    -webkit-backdrop-filter: blur(6px);
+  }
+
+  .lightbox-close-form {
+    position: absolute;
+    top: 0.75rem;
+    right: 0.75rem;
+    margin: 0;
+    z-index: 2;
+  }
+  .lightbox-close {
+    all: unset;
+    cursor: pointer;
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    width: 2.5rem;
+    height: 2.5rem;
+    border-radius: 9999px;
+    color: #f0b429;
+    background: rgba(12, 17, 26, 0.92);
+    border: 1px solid rgba(240, 180, 41, 0.35);
+    transition: background 160ms ease-out, transform 160ms ease-out, border-color 160ms ease-out;
+  }
+  .lightbox-close:hover {
+    background: rgba(240, 180, 41, 0.18);
+    border-color: rgba(240, 180, 41, 0.7);
+    transform: scale(1.06);
+  }
+  .lightbox-close:focus-visible {
+    outline: 2px solid #f0b429;
+    outline-offset: 2px;
+  }
+
+  .lightbox-image {
+    display: block;
+    width: 100%;
+    height: 100%;
+    object-fit: contain;
+    background: #060a13;
+    cursor: zoom-out;
+  }
+  .lightbox-caption {
+    position: absolute;
+    left: 0;
+    right: 0;
+    bottom: 0.5rem;
+    margin: 0;
+    text-align: center;
+    color: #9aa3b2;
+    font-size: 0.875rem;
+    padding: 0 1rem;
+  }
+
+  /* Open animation */
+  @keyframes lightbox-in {
+    from { opacity: 0; transform: scale(0.985); }
+    to   { opacity: 1; transform: scale(1); }
+  }
+  @keyframes lightbox-backdrop-in {
+    from { opacity: 0; }
+    to   { opacity: 1; }
+  }
+  .lightbox-dialog[open] {
+    animation: lightbox-in 220ms cubic-bezier(0.16, 1, 0.3, 1);
+  }
+  .lightbox-dialog[open]::backdrop {
+    animation: lightbox-backdrop-in 220ms ease-out;
+  }
+  @media (prefers-reduced-motion: reduce) {
+    .lightbox-zoom-badge {
+      transition: none;
+    }
+    .lightbox-dialog[open],
+    .lightbox-dialog[open]::backdrop {
+      animation: none;
+    }
+    .lightbox-close {
+      transition: none;
+    }
+  }
+</style>
+
+<script>
+  // Open lightbox on trigger click. Close on click of the image itself or
+  // the backdrop. Bundled by Astro — CSP script-src 'self'.
+  const triggers = document.querySelectorAll<HTMLButtonElement>('[data-lightbox-open]');
+  triggers.forEach((trigger) => {
+    trigger.addEventListener('click', () => {
+      const id = trigger.getAttribute('data-lightbox-open');
+      if (!id) return;
+      const dialog = document.getElementById(id);
+      if (dialog instanceof HTMLDialogElement) {
+        dialog.showModal();
+      }
+    });
+  });
+
+  const dialogs = document.querySelectorAll<HTMLDialogElement>('dialog.lightbox-dialog');
+  dialogs.forEach((dialog) => {
+    dialog.addEventListener('click', (event) => {
+      const target = event.target;
+      if (!(target instanceof HTMLElement)) return;
+      // Click on the dialog element itself (the backdrop area) or the image
+      // closes. Clicks on the close button are already handled by the native
+      // form[method=dialog].
+      if (target === dialog || target.classList.contains('lightbox-image')) {
+        dialog.close();
+      }
+    });
+  });
+</script>
diff --git a/src/components/sections/Hero.astro b/src/components/sections/Hero.astro
index dad984c..14301fb 100644
--- a/src/components/sections/Hero.astro
+++ b/src/components/sections/Hero.astro
@@ -1,6 +1,7 @@
 ---
 import CTAButtons from '../CTAButtons.astro';
 import TopographicBg from '../TopographicBg.astro';
+import Lightbox from '../Lightbox.astro';
 ---
 <section class="relative overflow-hidden border-b border-border">
   <TopographicBg opacity={0.22} lines={11} />
@@ -37,14 +38,12 @@ import TopographicBg from '../TopographicBg.astro';
       </div>
       <div class="lg:col-span-7 relative">
         <div class="hero-shot relative rounded-lg border border-border-strong bg-bg-elevated overflow-hidden">
-          <img
+          <Lightbox
             src="/product/exchange-detail.png"
             alt="Cameleer Mission Control — route execution detail with processor-level trace"
-            width="1920"
-            height="945"
+            width={1920}
+            height={945}
             loading="eager"
-            decoding="async"
-            class="block w-full h-auto"
           />
           <div class="absolute inset-0 ring-1 ring-inset ring-accent/10 pointer-events-none rounded-lg"></div>
         </div>
diff --git a/src/components/sections/ProductShowcase.astro b/src/components/sections/ProductShowcase.astro
index e600a54..863ae1a 100644
--- a/src/components/sections/ProductShowcase.astro
+++ b/src/components/sections/ProductShowcase.astro
@@ -1,5 +1,6 @@
 ---
 import TopographicBg from '../TopographicBg.astro';
+import Lightbox from '../Lightbox.astro';
 
 interface Callout {
   title: string;
@@ -37,14 +38,12 @@ const callouts: Callout[] = [
     <div class="grid lg:grid-cols-12 gap-10 lg:gap-14 items-start">
       <figure class="lg:col-span-8 relative">
         <div class="showcase-shot relative rounded-lg border border-border-strong bg-bg-elevated overflow-hidden">
-          <img
+          <Lightbox
             src="/product/error-detail.png"
             alt="Cameleer Mission Control — complex fulfillment route with circuit breaker, fallback, correlated audit route, and full error context"
-            width="1920"
-            height="945"
+            width={1920}
+            height={945}
             loading="lazy"
-            decoding="async"
-            class="block w-full h-auto"
           />
           <div class="absolute inset-0 ring-1 ring-inset ring-accent/10 pointer-events-none rounded-lg"></div>
         </div>