diff --git a/css/style.css b/css/style.css
index 0247aac..1fae253 100644
--- a/css/style.css
+++ b/css/style.css
@@ -1539,6 +1539,165 @@ footer.footer-modern a:hover {
 	text-decoration: none;
 }
 
+/* ========================================
+   SKIP-TO-CONTENT LINK (keyboard / a11y)
+   ======================================== */
+.skip-link {
+	position: fixed;
+	top: -120px;
+	left: 1rem;
+	z-index: 3000;
+	padding: 0.6rem 1rem;
+	background: var(--accent);
+	color: var(--accent-contrast);
+	border-radius: var(--radius-sm);
+	font-weight: 600;
+	text-decoration: none;
+	box-shadow: var(--shadow-md);
+	transition: top 0.15s ease;
+}
+
+.skip-link:focus {
+	top: 1rem;
+	color: var(--accent-contrast);
+	text-decoration: none;
+	outline: 2px solid var(--accent-contrast);
+	outline-offset: 2px;
+}
+
+/* The skip target shouldn't paint a focus ring when jumped to */
+#main-content:focus {
+	outline: none;
+}
+
+/* ========================================
+   READING PROGRESS BAR
+   ======================================== */
+.reading-progress {
+	position: fixed;
+	top: 0;
+	left: 0;
+	right: 0;
+	height: 3px;
+	z-index: 1040; /* above the fixed-top navbar (Bootstrap z-index 1030) */
+	background: transparent;
+	pointer-events: none;
+}
+
+.reading-progress-fill {
+	height: 100%;
+	width: 0;
+	background: var(--accent);
+	transition: width 0.05s linear;
+}
+
+/* ========================================
+   BACK-TO-TOP BUTTON
+   ======================================== */
+.back-to-top {
+	position: fixed;
+	bottom: 1.5rem;
+	right: 1.5rem;
+	z-index: 1035;
+	width: 44px;
+	height: 44px;
+	padding: 0;
+	border: none;
+	border-radius: 50%;
+	background: var(--accent);
+	color: var(--accent-contrast);
+	font-size: 1.25rem;
+	display: flex;
+	align-items: center;
+	justify-content: center;
+	cursor: pointer;
+	box-shadow: var(--shadow-md);
+	opacity: 0;
+	visibility: hidden;
+	transform: translateY(10px);
+	transition: opacity 0.2s ease, transform 0.2s ease, visibility 0s linear 0.2s, background 0.15s ease;
+}
+
+.back-to-top.is-visible {
+	opacity: 1;
+	visibility: visible;
+	transform: translateY(0);
+	transition: opacity 0.2s ease, transform 0.2s ease, visibility 0s linear 0s, background 0.15s ease;
+}
+
+.back-to-top:hover {
+	background: var(--accent-hover);
+}
+
+/* ========================================
+   COPY-TO-CLIPBOARD ON CODE BLOCKS
+   ======================================== */
+.code-block {
+	position: relative;
+}
+
+.code-copy {
+	position: absolute;
+	top: 0.5rem;
+	right: 0.5rem;
+	z-index: 2;
+	width: 32px;
+	height: 32px;
+	padding: 0;
+	display: inline-flex;
+	align-items: center;
+	justify-content: center;
+	border: 1px solid var(--border-color);
+	border-radius: var(--radius-sm);
+	background: var(--bg-subtle);
+	color: var(--text-secondary);
+	cursor: pointer;
+	opacity: 0;
+	transition: opacity 0.15s ease, color 0.15s ease, background 0.15s ease, border-color 0.15s ease;
+}
+
+.code-block:hover .code-copy,
+.code-copy:focus {
+	opacity: 1;
+}
+
+.code-copy:hover {
+	color: var(--text-primary);
+	border-color: var(--accent);
+}
+
+.code-copy.is-copied {
+	opacity: 1;
+	color: var(--accent-contrast);
+	background: var(--accent);
+	border-color: var(--accent);
+}
+
+.code-copy i {
+	font-size: 0.95rem;
+	line-height: 1;
+}
+
+/* Touch devices have no hover — keep the button discoverable */
+@media (hover: none) {
+	.code-copy { opacity: 0.7; }
+}
+
+/* ========================================
+   GPU HINTS — promote animated layers ahead of time
+   ======================================== */
+.lightbox-overlay img,
+.carousel-slide img {
+	will-change: transform;
+}
+
+/* Respect users who prefer reduced motion */
+@media (prefers-reduced-motion: reduce) {
+	.reading-progress-fill { transition: none; }
+	.back-to-top,
+	.back-to-top.is-visible { transform: none; }
+}
+
 /* ========================================
    RESPONSIVE
    ======================================== */
diff --git a/index.php b/index.php
index 66938c3..894a723 100644
--- a/index.php
+++ b/index.php
@@ -27,6 +27,9 @@
 </head>
 <body<?php echo $blowditHasHeadings ? ' class="has-toc"' : ''; ?>>
 
+	<!-- Skip to content (keyboard / screen-reader navigation) -->
+	<a class="skip-link" href="#main-content"><?php echo $L->get('Skip to content'); ?></a>
+
 	<!-- Load Bludit Plugins: Site Body Begin -->
 	<?php Theme::plugins('siteBodyBegin'); ?>
 
@@ -105,7 +108,7 @@
 	?>
 
 	<!-- Content -->
-	<div class="<?php echo $hasHeadings ? 'container-wide' : 'container'; ?>">
+	<div id="main-content" tabindex="-1" class="<?php echo $hasHeadings ? 'container-wide' : 'container'; ?>">
 		<div class="row">
 
 			<?php if ($hasHeadings): ?>
@@ -157,473 +160,31 @@
 		echo Theme::jsBootstrap();
 	?>
 
-	<!-- Theme picker -->
+	<!-- Theme behaviour: deferred, cached external bundle.
+	     The anti-flash theme bootstrap stays inline in head.php — it must
+	     run before the first paint and so cannot be deferred. -->
 	<script>
-		(function () {
-			var STORAGE_KEY = 'blowdit-theme';
-			var THEMES = ['light', 'dark', 'nord', 'dracula', 'catppuccin'];
-			var ICONS = {
-				light:      'bi-brightness-high',
-				dark:       'bi-moon-stars',
-				nord:       'bi-snow',
-				dracula:    'bi-droplet',
-				catppuccin: 'bi-cup'
-			};
-			var root   = document.documentElement;
-			var btn    = document.getElementById('theme-toggle');
-			var picker = document.getElementById('theme-picker');
-
-			function syncIcon(theme) {
-				if (!btn) return;
-				var icon = btn.querySelector('i');
-				if (!icon) return;
-				icon.className = 'bi ' + (ICONS[theme] || 'bi-circle-half');
-			}
-
-			function syncSwatches(theme) {
-				if (!picker) return;
-				Array.prototype.forEach.call(picker.querySelectorAll('.swatch'), function (s) {
-					s.classList.toggle('is-active', s.getAttribute('data-pick') === theme);
-				});
-			}
-
-			function apply(theme) {
-				root.setAttribute('data-theme', theme);
-				try { localStorage.setItem(STORAGE_KEY, theme); } catch (e) {}
-				document.cookie = 'blowdit-theme=' + theme + '; path=/; max-age=31536000; SameSite=Lax';
-				var bg = window.BLOWDIT_THEME_BG || {};
-				if (bg[theme]) { root.style.backgroundColor = bg[theme]; }
-				root.style.colorScheme = (theme === 'light') ? 'light' : 'dark';
-				syncIcon(theme);
-				syncSwatches(theme);
-			}
-
-			function openPicker() {
-				if (!picker) return;
-				picker.classList.add('is-open');
-				if (btn) btn.setAttribute('aria-expanded', 'true');
-			}
-
-			function closePicker() {
-				if (!picker) return;
-				picker.classList.remove('is-open');
-				if (btn) btn.setAttribute('aria-expanded', 'false');
-			}
-
-			// Swatch clicks
-			if (picker) {
-				Array.prototype.forEach.call(picker.querySelectorAll('.swatch'), function (s) {
-					s.addEventListener('click', function () {
-						apply(s.getAttribute('data-pick'));
-						closePicker();
-					});
-				});
-			}
-
-			// Toggle button: open / close picker
-			if (btn) {
-				btn.addEventListener('click', function (e) {
-					e.stopPropagation();
-					picker && picker.classList.contains('is-open') ? closePicker() : openPicker();
-				});
-			}
-
-			// Close on outside click
-			document.addEventListener('click', function (e) {
-				if (!picker || !picker.classList.contains('is-open')) return;
-				if (btn && btn.contains(e.target)) return;
-				if (picker.contains(e.target)) return;
-				closePicker();
-			});
-
-			// Initialise icons + active swatch
-			var current = root.getAttribute('data-theme') || 'light';
-			if (THEMES.indexOf(current) === -1) current = 'light';
-			syncIcon(current);
-			syncSwatches(current);
-
-			// Follow OS preference unless the visitor chose explicitly
-			if (window.matchMedia) {
-				window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', function (e) {
-					try { if (localStorage.getItem(STORAGE_KEY)) return; } catch (err) {}
-					apply(e.matches ? 'dark' : 'light');
-				});
-			}
-		})();
-	</script>
-
-	<!-- Randomise the order of the navigation / pages list on each load -->
-	<script>
-		(function () {
-			function shuffle(arr) {
-				for (var i = arr.length - 1; i > 0; i--) {
-					var j = Math.floor(Math.random() * (i + 1));
-					var tmp = arr[i]; arr[i] = arr[j]; arr[j] = tmp;
-				}
-				return arr;
-			}
-			var lists = document.querySelectorAll('.js-random-nav ul');
-			Array.prototype.forEach.call(lists, function (ul) {
-				var items = Array.prototype.filter.call(ul.children, function (el) {
-					return el.tagName === 'LI';
-				});
-				shuffle(items).forEach(function (li) { ul.appendChild(li); });
-			});
-		})();
-	</script>
-
-	<!-- Table of Contents: generate links from article headings + scroll-spy -->
-	<script>
-		(function () {
-			var tocNav = document.getElementById('toc-nav');
-			if (!tocNav) return;
-
-			var content = document.querySelector('.content');
-			if (!content) return;
-
-			var headings = content.querySelectorAll('h2, h3, h4');
-			if (headings.length === 0) return;
-
-			// Ensure every heading has a stable anchor ID
-			var usedIds = {};
-			Array.prototype.forEach.call(headings, function (h) {
-				if (!h.id) {
-					var base = h.textContent.trim().toLowerCase()
-						.replace(/[^a-z0-9\s-]/g, '')
-						.replace(/\s+/g, '-')
-						.replace(/^-+|-+$/g, '') || 'heading';
-					var id = base, n = 2;
-					while (usedIds[id]) { id = base + '-' + (n++); }
-					usedIds[id] = true;
-					h.id = id;
-				} else {
-					usedIds[h.id] = true;
-				}
-			});
-
-			// Build the list
-			var ul = document.createElement('ul');
-			ul.className = 'toc-list';
-			Array.prototype.forEach.call(headings, function (h) {
-				var li = document.createElement('li');
-				li.className = 'toc-item toc-' + h.tagName.toLowerCase();
-				var a = document.createElement('a');
-				a.href = '#' + h.id;
-				a.textContent = h.textContent;
-				a.className = 'toc-link';
-				li.appendChild(a);
-				ul.appendChild(li);
-			});
-			tocNav.appendChild(ul);
-
-			// Scroll-spy: highlight the last heading that has scrolled past the top
-			var headingArr = Array.prototype.slice.call(headings);
-
-			function updateActive() {
-				var scrollY = window.scrollY || window.pageYOffset;
-				var threshold = scrollY + 120; // offset for navbar height
-				var active = null;
-				headingArr.forEach(function (h) {
-					var top = h.getBoundingClientRect().top + scrollY;
-					if (top <= threshold) active = h;
-				});
-				var links = tocNav.querySelectorAll('.toc-link');
-				Array.prototype.forEach.call(links, function (a) { a.classList.remove('active'); });
-				if (active) {
-					var link = tocNav.querySelector('a[href="#' + active.id + '"]');
-					if (link) link.classList.add('active');
-				}
-			}
-
-			window.addEventListener('scroll', updateActive, { passive: true });
-			updateActive();
-		})();
-	</script>
-
-	<!-- Tabbed code blocks: transforms ```tabs fences into a tab UI -->
-	<script>
-		(function () {
-			// Match both "language-tabs" (Parsedown ≥ 1.7) and bare "tabs" (older Bludit builds)
-			var blocks = document.querySelectorAll(
-				'pre > code.language-tabs, pre > code.tabs'
-			);
-			Array.prototype.forEach.call(blocks, function (code) {
-				var pre  = code.parentNode;
-				var raw  = code.textContent;
-
-				// Supports "[Name]" and "@tab Name" as tab headers
-				var tabs = [];
-				var current = null;
-				raw.split('\n').forEach(function (line) {
-					line = line.replace(/\r$/, ''); // strip Windows CR
-					var m = line.match(/^\[([^\]]+)\]\s*$/) ||
-					        line.match(/^@tab\s+(.+?)\s*$/);
-					if (m) {
-						current = { name: m[1], lines: [] };
-						tabs.push(current);
-					} else if (current) {
-						current.lines.push(line);
-					}
-				});
-				if (!tabs.length) return;
-
-				// Trim leading / trailing blank lines from each tab
-				tabs.forEach(function (t) {
-					while (t.lines.length && !t.lines[0].trim())            t.lines.shift();
-					while (t.lines.length && !t.lines[t.lines.length - 1].trim()) t.lines.pop();
-				});
-
-				// Build the tab group
-				var group = document.createElement('div');
-				group.className = 'tab-group';
-
-				var list = document.createElement('div');
-				list.className = 'tab-list';
-				list.setAttribute('role', 'tablist');
-				group.appendChild(list);
-
-				var panels = [];
-				tabs.forEach(function (t, i) {
-					// Tab button
-					var btn = document.createElement('button');
-					btn.type = 'button';
-					btn.className = 'tab-btn' + (i === 0 ? ' is-active' : '');
-					btn.setAttribute('role', 'tab');
-					btn.textContent = t.name;
-					list.appendChild(btn);
-
-					// Tab panel
-					var panel = document.createElement('div');
-					panel.className = 'tab-panel' + (i === 0 ? ' is-active' : '');
-					panel.setAttribute('role', 'tabpanel');
-					var panelPre  = document.createElement('pre');
-					var panelCode = document.createElement('code');
-					panelCode.textContent = t.lines.join('\n');
-					panelPre.appendChild(panelCode);
-					panel.appendChild(panelPre);
-					group.appendChild(panel);
-					panels.push({ btn: btn, panel: panel });
-
-					btn.addEventListener('click', function () {
-						panels.forEach(function (p) {
-							p.btn.classList.remove('is-active');
-							p.panel.classList.remove('is-active');
-						});
-						btn.classList.add('is-active');
-						panel.classList.add('is-active');
-					});
-				});
-
-				pre.parentNode.replaceChild(group, pre);
-			});
-		})();
-	</script>
-
-	<!-- Image carousel: transforms ```carousel fences into a slideshow -->
-	<script>
-		(function () {
-			var blocks = document.querySelectorAll('pre > code.language-carousel');
-			Array.prototype.forEach.call(blocks, function (code) {
-				var pre = code.parentNode;
-
-				// Accepts "![alt](url)", "url | caption", or bare "url"
-				var slides = [];
-				code.textContent.split('\n').forEach(function (line) {
-					line = line.replace(/\r$/, '').trim();
-					if (!line) return;
-					// Markdown image syntax: ![alt text](url)
-					var md = line.match(/^!\[([^\]]*)\]\(([^)]+)\)\s*$/);
-					if (md) {
-						slides.push({ url: md[2].trim(), caption: md[1].trim() });
-						return;
-					}
-					// Plain: "url | caption" or bare url
-					var parts = line.split('|');
-					var url = parts[0].trim();
-					if (url) slides.push({ url: url, caption: (parts[1] || '').trim() });
-				});
-				if (!slides.length) return;
-
-				var car   = document.createElement('div');
-				car.className = 'carousel';
-
-				var track = document.createElement('div');
-				track.className = 'carousel-track';
-				car.appendChild(track);
-
-				var slideEls = [];
-				var dotEls   = [];
-				var current  = 0;
-
-				slides.forEach(function (s, i) {
-					var slide = document.createElement('div');
-					slide.className = 'carousel-slide' + (i === 0 ? ' is-active' : '');
-					var img = document.createElement('img');
-					img.src = s.url;
-					img.alt = s.caption;
-					img.loading = 'lazy';
-					slide.appendChild(img);
-					if (s.caption) {
-						var cap = document.createElement('p');
-						cap.className = 'carousel-caption';
-						cap.textContent = s.caption;
-						slide.appendChild(cap);
-					}
-					track.appendChild(slide);
-					slideEls.push(slide);
-				});
-
-				function goTo(idx) {
-					slideEls[current].classList.remove('is-active');
-					if (dotEls[current]) dotEls[current].classList.remove('is-active');
-					current = (idx + slides.length) % slides.length;
-					slideEls[current].classList.add('is-active');
-					if (dotEls[current]) dotEls[current].classList.add('is-active');
-				}
-
-				if (slides.length > 1) {
-					var prev = document.createElement('button');
-					prev.type = 'button'; prev.className = 'carousel-arrow carousel-prev';
-					prev.textContent = '‹';
-					prev.addEventListener('click', function () { goTo(current - 1); });
-					car.appendChild(prev);
-
-					var next = document.createElement('button');
-					next.type = 'button'; next.className = 'carousel-arrow carousel-next';
-					next.textContent = '›';
-					next.addEventListener('click', function () { goTo(current + 1); });
-					car.appendChild(next);
-
-					var dots = document.createElement('div');
-					dots.className = 'carousel-dots';
-					slides.forEach(function (_, i) {
-						var dot = document.createElement('button');
-						dot.type = 'button';
-						dot.className = 'carousel-dot' + (i === 0 ? ' is-active' : '');
-						dot.addEventListener('click', function () { goTo(i); });
-						dots.appendChild(dot);
-						dotEls.push(dot);
-					});
-					car.appendChild(dots);
-
-					// Swipe support
-					var startX = 0;
-					track.addEventListener('touchstart', function (e) { startX = e.touches[0].clientX; }, { passive: true });
-					track.addEventListener('touchend', function (e) {
-						var dx = e.changedTouches[0].clientX - startX;
-						if (Math.abs(dx) > 40) goTo(dx < 0 ? current + 1 : current - 1);
-					}, { passive: true });
-				}
-
-				pre.parentNode.replaceChild(car, pre);
-			});
-		})();
-	</script>
-
-	<!-- Lightbox: click any article image to zoom; carousel-aware prev/next -->
-	<script>
-		(function () {
-			var content = document.querySelector('.content');
-			if (!content) return;
-
-			var images = content.querySelectorAll('img');
-			if (!images.length) return;
-
-			// Build overlay with optional prev/next arrows for carousel galleries
-			var overlay = document.createElement('div');
-			overlay.className = 'lightbox-overlay';
-
-			var prevBtn = document.createElement('button');
-			prevBtn.type = 'button';
-			prevBtn.className = 'lightbox-arrow lightbox-prev';
-			prevBtn.textContent = '‹'; // ‹
-
-			var zoomed = document.createElement('img');
-
-			var nextBtn = document.createElement('button');
-			nextBtn.type = 'button';
-			nextBtn.className = 'lightbox-arrow lightbox-next';
-			nextBtn.textContent = '›'; // ›
-
-			overlay.appendChild(prevBtn);
-			overlay.appendChild(zoomed);
-			overlay.appendChild(nextBtn);
-			document.body.appendChild(overlay);
-
-			var gallery = [];   // images in the current carousel (empty = single image)
-			var galIdx  = 0;
-
-			function showAt(idx) {
-				galIdx = (idx + gallery.length) % gallery.length;
-				zoomed.src = gallery[galIdx].src;
-				zoomed.alt = gallery[galIdx].alt || '';
-			}
-
-			function open(el) {
-				// If the image lives inside a carousel, collect all slides for navigation
-				var car = el.closest ? el.closest('.carousel') : null;
-				if (car) {
-					gallery = Array.prototype.slice.call(car.querySelectorAll('.carousel-slide img'));
-					galIdx  = gallery.indexOf(el);
-					if (galIdx === -1) galIdx = 0;
-				} else {
-					gallery = [el];
-					galIdx  = 0;
-				}
-				var hasMultiple = gallery.length > 1;
-				prevBtn.style.display = hasMultiple ? '' : 'none';
-				nextBtn.style.display = hasMultiple ? '' : 'none';
-				zoomed.src = el.src;
-				zoomed.alt = el.alt || '';
-				overlay.classList.add('is-open');
-				document.body.style.overflow = 'hidden';
-			}
-
-			function close() {
-				overlay.classList.remove('is-open');
-				document.body.style.overflow = '';
-			}
-
-			prevBtn.addEventListener('click', function (e) {
-				e.stopPropagation();
-				showAt(galIdx - 1);
-			});
-			nextBtn.addEventListener('click', function (e) {
-				e.stopPropagation();
-				showAt(galIdx + 1);
-			});
-
-			function wrapImage(el) {
-				if (el.naturalWidth > 0 && el.naturalWidth < 100) return;
-				if (el.naturalHeight > 0 && el.naturalHeight < 100) return;
-				var wrap = document.createElement('span');
-				wrap.className = 'zoomable-wrap';
-				el.parentNode.insertBefore(wrap, el);
-				wrap.appendChild(el);
-				el.addEventListener('click', function () { open(el); });
-			}
-
-			Array.prototype.forEach.call(images, function (el) {
-				if (el.complete && el.naturalWidth) {
-					wrapImage(el);
-				} else {
-					el.addEventListener('load', function () { wrapImage(el); });
-				}
-			});
-
-			// Close on backdrop click (not on arrows or image)
-			overlay.addEventListener('click', function (e) {
-				if (e.target === overlay) close();
-			});
-
-			document.addEventListener('keydown', function (e) {
-				if (!overlay.classList.contains('is-open')) return;
-				if (e.key === 'Escape' || e.key === 'Esc')   close();
-				if (e.key === 'ArrowLeft'  && gallery.length > 1) showAt(galIdx - 1);
-				if (e.key === 'ArrowRight' && gallery.length > 1) showAt(galIdx + 1);
-			});
-		})();
+		// Localised UI strings for the deferred bundle. $L->get() falls back to
+		// the key itself when a translation is missing, so this is safe in any language.
+		window.BLOWDIT_I18N = {
+			copy:        <?php echo json_encode($L->get('Copy')); ?>,
+			copied:      <?php echo json_encode($L->get('Copied')); ?>,
+			copyCode:    <?php echo json_encode($L->get('Copy code')); ?>,
+			backToTop:   <?php echo json_encode($L->get('Back to top')); ?>,
+			prevSlide:   <?php echo json_encode($L->get('Previous slide')); ?>,
+			nextSlide:   <?php echo json_encode($L->get('Next slide')); ?>,
+			goToSlide:   <?php echo json_encode($L->get('Go to slide')); ?>,
+			prevImage:   <?php echo json_encode($L->get('Previous image')); ?>,
+			nextImage:   <?php echo json_encode($L->get('Next image')); ?>,
+			imageViewer: <?php echo json_encode($L->get('Image viewer')); ?>
+		};
 	</script>
+	<?php
+		// Cache-busted by file mtime (mirrors the style.css approach in head.php).
+		$jsVersion = @filemtime(THEME_DIR_JS . 'blowdit.js');
+		$jsSrc = DOMAIN_THEME . 'js/blowdit.js' . ($jsVersion ? '?v=' . $jsVersion : '');
+	?>
+	<script defer src="<?php echo $jsSrc; ?>"></script>
 
 	<!-- Load Bludit Plugins: Site Body End -->
 	<?php Theme::plugins('siteBodyEnd'); ?>
diff --git a/js/blowdit.js b/js/blowdit.js
new file mode 100644
index 0000000..d38543d
--- /dev/null
+++ b/js/blowdit.js
@@ -0,0 +1,670 @@
+/* ============================================================
+   BLOWDIT — theme behaviour
+   Deferred, cacheable bundle of all client-side enhancements.
+   Loaded with <script defer> from index.php, so the DOM is fully
+   parsed before any of these IIFEs run (no DOMContentLoaded needed).
+
+   NOTE: the anti-flash theme bootstrap stays inline in head.php —
+   it must run before the first paint and cannot be deferred.
+   ============================================================ */
+(function () {
+	'use strict';
+
+	// Localised UI strings (overridable via window.BLOWDIT_I18N, set in index.php).
+	var I18N = window.BLOWDIT_I18N || {};
+	var T = {
+		copy:        I18N.copy        || 'Copy',
+		copied:      I18N.copied      || 'Copied',
+		copyCode:    I18N.copyCode    || 'Copy code',
+		backToTop:   I18N.backToTop   || 'Back to top',
+		prevSlide:   I18N.prevSlide   || 'Previous slide',
+		nextSlide:   I18N.nextSlide   || 'Next slide',
+		goToSlide:   I18N.goToSlide   || 'Go to slide',
+		prevImage:   I18N.prevImage   || 'Previous image',
+		nextImage:   I18N.nextImage   || 'Next image',
+		imageViewer: I18N.imageViewer || 'Image viewer'
+	};
+
+	/* --------------------------------------------------------
+	   Theme picker
+	   -------------------------------------------------------- */
+	(function () {
+		var STORAGE_KEY = 'blowdit-theme';
+		var THEMES = ['light', 'dark', 'nord', 'dracula', 'catppuccin'];
+		var ICONS = {
+			light:      'bi-brightness-high',
+			dark:       'bi-moon-stars',
+			nord:       'bi-snow',
+			dracula:    'bi-droplet',
+			catppuccin: 'bi-cup'
+		};
+		var root   = document.documentElement;
+		var btn    = document.getElementById('theme-toggle');
+		var picker = document.getElementById('theme-picker');
+
+		function syncIcon(theme) {
+			if (!btn) return;
+			var icon = btn.querySelector('i');
+			if (!icon) return;
+			icon.className = 'bi ' + (ICONS[theme] || 'bi-circle-half');
+		}
+
+		function syncSwatches(theme) {
+			if (!picker) return;
+			Array.prototype.forEach.call(picker.querySelectorAll('.swatch'), function (s) {
+				s.classList.toggle('is-active', s.getAttribute('data-pick') === theme);
+			});
+		}
+
+		function apply(theme) {
+			root.setAttribute('data-theme', theme);
+			try { localStorage.setItem(STORAGE_KEY, theme); } catch (e) {}
+			document.cookie = 'blowdit-theme=' + theme + '; path=/; max-age=31536000; SameSite=Lax';
+			var bg = window.BLOWDIT_THEME_BG || {};
+			if (bg[theme]) { root.style.backgroundColor = bg[theme]; }
+			root.style.colorScheme = (theme === 'light') ? 'light' : 'dark';
+			syncIcon(theme);
+			syncSwatches(theme);
+		}
+
+		function openPicker() {
+			if (!picker) return;
+			picker.classList.add('is-open');
+			if (btn) btn.setAttribute('aria-expanded', 'true');
+		}
+
+		function closePicker() {
+			if (!picker) return;
+			picker.classList.remove('is-open');
+			if (btn) btn.setAttribute('aria-expanded', 'false');
+		}
+
+		// Swatch clicks
+		if (picker) {
+			Array.prototype.forEach.call(picker.querySelectorAll('.swatch'), function (s) {
+				s.addEventListener('click', function () {
+					apply(s.getAttribute('data-pick'));
+					closePicker();
+				});
+			});
+		}
+
+		// Toggle button: open / close picker
+		if (btn) {
+			btn.addEventListener('click', function (e) {
+				e.stopPropagation();
+				picker && picker.classList.contains('is-open') ? closePicker() : openPicker();
+			});
+		}
+
+		// Close on outside click
+		document.addEventListener('click', function (e) {
+			if (!picker || !picker.classList.contains('is-open')) return;
+			if (btn && btn.contains(e.target)) return;
+			if (picker.contains(e.target)) return;
+			closePicker();
+		});
+
+		// Initialise icons + active swatch
+		var current = root.getAttribute('data-theme') || 'light';
+		if (THEMES.indexOf(current) === -1) current = 'light';
+		syncIcon(current);
+		syncSwatches(current);
+
+		// Follow OS preference unless the visitor chose explicitly
+		if (window.matchMedia) {
+			window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', function (e) {
+				try { if (localStorage.getItem(STORAGE_KEY)) return; } catch (err) {}
+				apply(e.matches ? 'dark' : 'light');
+			});
+		}
+	})();
+
+	/* --------------------------------------------------------
+	   Randomise the order of the navigation / pages list on each load
+	   -------------------------------------------------------- */
+	(function () {
+		function shuffle(arr) {
+			for (var i = arr.length - 1; i > 0; i--) {
+				var j = Math.floor(Math.random() * (i + 1));
+				var tmp = arr[i]; arr[i] = arr[j]; arr[j] = tmp;
+			}
+			return arr;
+		}
+		var lists = document.querySelectorAll('.js-random-nav ul');
+		Array.prototype.forEach.call(lists, function (ul) {
+			var items = Array.prototype.filter.call(ul.children, function (el) {
+				return el.tagName === 'LI';
+			});
+			shuffle(items).forEach(function (li) { ul.appendChild(li); });
+		});
+	})();
+
+	/* --------------------------------------------------------
+	   Table of Contents: generate links from article headings + scroll-spy
+	   -------------------------------------------------------- */
+	(function () {
+		var tocNav = document.getElementById('toc-nav');
+		if (!tocNav) return;
+
+		var content = document.querySelector('.content');
+		if (!content) return;
+
+		var headings = content.querySelectorAll('h2, h3, h4');
+		if (headings.length === 0) return;
+
+		// Ensure every heading has a stable anchor ID
+		var usedIds = {};
+		Array.prototype.forEach.call(headings, function (h) {
+			if (!h.id) {
+				var base = h.textContent.trim().toLowerCase()
+					.replace(/[^a-z0-9\s-]/g, '')
+					.replace(/\s+/g, '-')
+					.replace(/^-+|-+$/g, '') || 'heading';
+				var id = base, n = 2;
+				while (usedIds[id]) { id = base + '-' + (n++); }
+				usedIds[id] = true;
+				h.id = id;
+			} else {
+				usedIds[h.id] = true;
+			}
+		});
+
+		// Build the list
+		var ul = document.createElement('ul');
+		ul.className = 'toc-list';
+		Array.prototype.forEach.call(headings, function (h) {
+			var li = document.createElement('li');
+			li.className = 'toc-item toc-' + h.tagName.toLowerCase();
+			var a = document.createElement('a');
+			a.href = '#' + h.id;
+			a.textContent = h.textContent;
+			a.className = 'toc-link';
+			li.appendChild(a);
+			ul.appendChild(li);
+		});
+		tocNav.appendChild(ul);
+
+		// Scroll-spy: highlight the last heading that has scrolled past the top
+		var headingArr = Array.prototype.slice.call(headings);
+
+		function updateActive() {
+			var scrollY = window.scrollY || window.pageYOffset;
+			var threshold = scrollY + 120; // offset for navbar height
+			var active = null;
+			headingArr.forEach(function (h) {
+				var top = h.getBoundingClientRect().top + scrollY;
+				if (top <= threshold) active = h;
+			});
+			var links = tocNav.querySelectorAll('.toc-link');
+			Array.prototype.forEach.call(links, function (a) { a.classList.remove('active'); });
+			if (active) {
+				var link = tocNav.querySelector('a[href="#' + active.id + '"]');
+				if (link) link.classList.add('active');
+			}
+		}
+
+		window.addEventListener('scroll', updateActive, { passive: true });
+		updateActive();
+	})();
+
+	/* --------------------------------------------------------
+	   Tabbed code blocks: transforms ```tabs fences into a tab UI
+	   -------------------------------------------------------- */
+	(function () {
+		var tabGroupSeq = 0;
+		// Match both "language-tabs" (Parsedown >= 1.7) and bare "tabs" (older Bludit builds)
+		var blocks = document.querySelectorAll(
+			'pre > code.language-tabs, pre > code.tabs'
+		);
+		Array.prototype.forEach.call(blocks, function (code) {
+			var pre  = code.parentNode;
+			var raw  = code.textContent;
+
+			// Supports "[Name]" and "@tab Name" as tab headers
+			var tabs = [];
+			var current = null;
+			raw.split('\n').forEach(function (line) {
+				line = line.replace(/\r$/, ''); // strip Windows CR
+				var m = line.match(/^\[([^\]]+)\]\s*$/) ||
+				        line.match(/^@tab\s+(.+?)\s*$/);
+				if (m) {
+					current = { name: m[1], lines: [] };
+					tabs.push(current);
+				} else if (current) {
+					current.lines.push(line);
+				}
+			});
+			if (!tabs.length) return;
+
+			// Trim leading / trailing blank lines from each tab
+			tabs.forEach(function (t) {
+				while (t.lines.length && !t.lines[0].trim())            t.lines.shift();
+				while (t.lines.length && !t.lines[t.lines.length - 1].trim()) t.lines.pop();
+			});
+
+			// Build the tab group
+			var groupId = 'tabgroup-' + (++tabGroupSeq);
+			var group = document.createElement('div');
+			group.className = 'tab-group';
+
+			var list = document.createElement('div');
+			list.className = 'tab-list';
+			list.setAttribute('role', 'tablist');
+			group.appendChild(list);
+
+			var panels = [];
+			tabs.forEach(function (t, i) {
+				var active = (i === 0);
+				var tabId   = groupId + '-tab-' + i;
+				var panelId = groupId + '-panel-' + i;
+
+				// Tab button
+				var btn = document.createElement('button');
+				btn.type = 'button';
+				btn.className = 'tab-btn' + (active ? ' is-active' : '');
+				btn.id = tabId;
+				btn.setAttribute('role', 'tab');
+				btn.setAttribute('aria-selected', active ? 'true' : 'false');
+				btn.setAttribute('aria-controls', panelId);
+				btn.setAttribute('tabindex', active ? '0' : '-1');
+				btn.textContent = t.name;
+				list.appendChild(btn);
+
+				// Tab panel
+				var panel = document.createElement('div');
+				panel.className = 'tab-panel' + (active ? ' is-active' : '');
+				panel.id = panelId;
+				panel.setAttribute('role', 'tabpanel');
+				panel.setAttribute('aria-labelledby', tabId);
+				panel.setAttribute('tabindex', '0');
+				if (!active) panel.hidden = true;
+				var panelPre  = document.createElement('pre');
+				var panelCode = document.createElement('code');
+				panelCode.textContent = t.lines.join('\n');
+				panelPre.appendChild(panelCode);
+				panel.appendChild(panelPre);
+				group.appendChild(panel);
+				panels.push({ btn: btn, panel: panel });
+
+				function activate() {
+					panels.forEach(function (p) {
+						p.btn.classList.remove('is-active');
+						p.btn.setAttribute('aria-selected', 'false');
+						p.btn.setAttribute('tabindex', '-1');
+						p.panel.classList.remove('is-active');
+						p.panel.hidden = true;
+					});
+					btn.classList.add('is-active');
+					btn.setAttribute('aria-selected', 'true');
+					btn.setAttribute('tabindex', '0');
+					panel.classList.add('is-active');
+					panel.hidden = false;
+				}
+
+				btn.addEventListener('click', activate);
+				btn.addEventListener('keydown', function (e) {
+					var nextIdx = null;
+					if (e.key === 'ArrowRight') nextIdx = (i + 1) % panels.length;
+					else if (e.key === 'ArrowLeft') nextIdx = (i - 1 + panels.length) % panels.length;
+					if (nextIdx !== null) {
+						e.preventDefault();
+						panels[nextIdx].btn.click();
+						panels[nextIdx].btn.focus();
+					}
+				});
+			});
+
+			pre.parentNode.replaceChild(group, pre);
+		});
+	})();
+
+	/* --------------------------------------------------------
+	   Image carousel: transforms ```carousel fences into a slideshow
+	   -------------------------------------------------------- */
+	(function () {
+		var blocks = document.querySelectorAll('pre > code.language-carousel');
+		Array.prototype.forEach.call(blocks, function (code) {
+			var pre = code.parentNode;
+
+			// Accepts "![alt](url)", "url | caption", or bare "url"
+			var slides = [];
+			code.textContent.split('\n').forEach(function (line) {
+				line = line.replace(/\r$/, '').trim();
+				if (!line) return;
+				// Markdown image syntax: ![alt text](url)
+				var md = line.match(/^!\[([^\]]*)\]\(([^)]+)\)\s*$/);
+				if (md) {
+					slides.push({ url: md[2].trim(), caption: md[1].trim() });
+					return;
+				}
+				// Plain: "url | caption" or bare url
+				var parts = line.split('|');
+				var url = parts[0].trim();
+				if (url) slides.push({ url: url, caption: (parts[1] || '').trim() });
+			});
+			if (!slides.length) return;
+
+			var car   = document.createElement('div');
+			car.className = 'carousel';
+			car.setAttribute('role', 'group');
+			car.setAttribute('aria-roledescription', 'carousel');
+
+			var track = document.createElement('div');
+			track.className = 'carousel-track';
+			car.appendChild(track);
+
+			var slideEls = [];
+			var dotEls   = [];
+			var current  = 0;
+
+			slides.forEach(function (s, i) {
+				var slide = document.createElement('div');
+				slide.className = 'carousel-slide' + (i === 0 ? ' is-active' : '');
+				var img = document.createElement('img');
+				img.src = s.url;
+				img.alt = s.caption;
+				img.loading = 'lazy';
+				slide.appendChild(img);
+				if (s.caption) {
+					var cap = document.createElement('p');
+					cap.className = 'carousel-caption';
+					cap.textContent = s.caption;
+					slide.appendChild(cap);
+				}
+				track.appendChild(slide);
+				slideEls.push(slide);
+			});
+
+			function goTo(idx) {
+				slideEls[current].classList.remove('is-active');
+				if (dotEls[current]) dotEls[current].classList.remove('is-active');
+				current = (idx + slides.length) % slides.length;
+				slideEls[current].classList.add('is-active');
+				if (dotEls[current]) dotEls[current].classList.add('is-active');
+			}
+
+			if (slides.length > 1) {
+				var prev = document.createElement('button');
+				prev.type = 'button'; prev.className = 'carousel-arrow carousel-prev';
+				prev.setAttribute('aria-label', T.prevSlide);
+				prev.textContent = '‹';
+				prev.addEventListener('click', function () { goTo(current - 1); });
+				car.appendChild(prev);
+
+				var next = document.createElement('button');
+				next.type = 'button'; next.className = 'carousel-arrow carousel-next';
+				next.setAttribute('aria-label', T.nextSlide);
+				next.textContent = '›';
+				next.addEventListener('click', function () { goTo(current + 1); });
+				car.appendChild(next);
+
+				var dots = document.createElement('div');
+				dots.className = 'carousel-dots';
+				slides.forEach(function (_, i) {
+					var dot = document.createElement('button');
+					dot.type = 'button';
+					dot.className = 'carousel-dot' + (i === 0 ? ' is-active' : '');
+					dot.setAttribute('aria-label', T.goToSlide + ' ' + (i + 1));
+					dot.addEventListener('click', function () { goTo(i); });
+					dots.appendChild(dot);
+					dotEls.push(dot);
+				});
+				car.appendChild(dots);
+
+				// Swipe support
+				var startX = 0;
+				track.addEventListener('touchstart', function (e) { startX = e.touches[0].clientX; }, { passive: true });
+				track.addEventListener('touchend', function (e) {
+					var dx = e.changedTouches[0].clientX - startX;
+					if (Math.abs(dx) > 40) goTo(dx < 0 ? current + 1 : current - 1);
+				}, { passive: true });
+			}
+
+			pre.parentNode.replaceChild(car, pre);
+		});
+	})();
+
+	/* --------------------------------------------------------
+	   Lightbox: click any article image to zoom; carousel-aware prev/next
+	   -------------------------------------------------------- */
+	(function () {
+		var content = document.querySelector('.content');
+		if (!content) return;
+
+		var images = content.querySelectorAll('img');
+		if (!images.length) return;
+
+		// Build overlay with optional prev/next arrows for carousel galleries
+		var overlay = document.createElement('div');
+		overlay.className = 'lightbox-overlay';
+		overlay.setAttribute('role', 'dialog');
+		overlay.setAttribute('aria-modal', 'true');
+		overlay.setAttribute('aria-label', T.imageViewer);
+
+		var prevBtn = document.createElement('button');
+		prevBtn.type = 'button';
+		prevBtn.className = 'lightbox-arrow lightbox-prev';
+		prevBtn.setAttribute('aria-label', T.prevImage);
+		prevBtn.textContent = '‹'; // ‹
+
+		var zoomed = document.createElement('img');
+
+		var nextBtn = document.createElement('button');
+		nextBtn.type = 'button';
+		nextBtn.className = 'lightbox-arrow lightbox-next';
+		nextBtn.setAttribute('aria-label', T.nextImage);
+		nextBtn.textContent = '›'; // ›
+
+		overlay.appendChild(prevBtn);
+		overlay.appendChild(zoomed);
+		overlay.appendChild(nextBtn);
+		document.body.appendChild(overlay);
+
+		var gallery = [];   // images in the current carousel (empty = single image)
+		var galIdx  = 0;
+
+		function showAt(idx) {
+			galIdx = (idx + gallery.length) % gallery.length;
+			zoomed.src = gallery[galIdx].src;
+			zoomed.alt = gallery[galIdx].alt || '';
+		}
+
+		function open(el) {
+			// If the image lives inside a carousel, collect all slides for navigation
+			var car = el.closest ? el.closest('.carousel') : null;
+			if (car) {
+				gallery = Array.prototype.slice.call(car.querySelectorAll('.carousel-slide img'));
+				galIdx  = gallery.indexOf(el);
+				if (galIdx === -1) galIdx = 0;
+			} else {
+				gallery = [el];
+				galIdx  = 0;
+			}
+			var hasMultiple = gallery.length > 1;
+			prevBtn.style.display = hasMultiple ? '' : 'none';
+			nextBtn.style.display = hasMultiple ? '' : 'none';
+			zoomed.src = el.src;
+			zoomed.alt = el.alt || '';
+			overlay.classList.add('is-open');
+			document.body.style.overflow = 'hidden';
+		}
+
+		function close() {
+			overlay.classList.remove('is-open');
+			document.body.style.overflow = '';
+		}
+
+		prevBtn.addEventListener('click', function (e) {
+			e.stopPropagation();
+			showAt(galIdx - 1);
+		});
+		nextBtn.addEventListener('click', function (e) {
+			e.stopPropagation();
+			showAt(galIdx + 1);
+		});
+
+		function wrapImage(el) {
+			if (el.naturalWidth > 0 && el.naturalWidth < 100) return;
+			if (el.naturalHeight > 0 && el.naturalHeight < 100) return;
+			var wrap = document.createElement('span');
+			wrap.className = 'zoomable-wrap';
+			el.parentNode.insertBefore(wrap, el);
+			wrap.appendChild(el);
+			el.addEventListener('click', function () { open(el); });
+		}
+
+		Array.prototype.forEach.call(images, function (el) {
+			if (el.complete && el.naturalWidth) {
+				wrapImage(el);
+			} else {
+				el.addEventListener('load', function () { wrapImage(el); });
+			}
+		});
+
+		// Close on backdrop click (not on arrows or image)
+		overlay.addEventListener('click', function (e) {
+			if (e.target === overlay) close();
+		});
+
+		document.addEventListener('keydown', function (e) {
+			if (!overlay.classList.contains('is-open')) return;
+			if (e.key === 'Escape' || e.key === 'Esc')   close();
+			if (e.key === 'ArrowLeft'  && gallery.length > 1) showAt(galIdx - 1);
+			if (e.key === 'ArrowRight' && gallery.length > 1) showAt(galIdx + 1);
+		});
+	})();
+
+	/* --------------------------------------------------------
+	   Copy-to-clipboard buttons on code blocks
+	   Runs after the tabs/carousel transforms so it only targets real
+	   code blocks (including the generated tab panels), not raw fences.
+	   -------------------------------------------------------- */
+	(function () {
+		function copyText(text) {
+			if (navigator.clipboard && navigator.clipboard.writeText) {
+				return navigator.clipboard.writeText(text);
+			}
+			// Fallback for older / non-secure-context browsers
+			return new Promise(function (resolve, reject) {
+				try {
+					var ta = document.createElement('textarea');
+					ta.value = text;
+					ta.style.position = 'fixed';
+					ta.style.opacity = '0';
+					document.body.appendChild(ta);
+					ta.select();
+					document.execCommand('copy');
+					document.body.removeChild(ta);
+					resolve();
+				} catch (e) { reject(e); }
+			});
+		}
+
+		function enhance(pre) {
+			// Skip if already wrapped
+			if (pre.parentNode && pre.parentNode.classList &&
+			    pre.parentNode.classList.contains('code-block')) return;
+
+			var wrap = document.createElement('div');
+			wrap.className = 'code-block';
+			pre.parentNode.insertBefore(wrap, pre);
+			wrap.appendChild(pre);
+
+			var btn = document.createElement('button');
+			btn.type = 'button';
+			btn.className = 'code-copy';
+			btn.setAttribute('aria-label', T.copyCode);
+			btn.innerHTML = '<i class="bi bi-clipboard" aria-hidden="true"></i>';
+
+			var resetTimer = null;
+			btn.addEventListener('click', function () {
+				var code = pre.querySelector('code');
+				var text = (code ? code.textContent : pre.textContent) || '';
+				copyText(text).then(function () {
+					btn.classList.add('is-copied');
+					btn.innerHTML = '<i class="bi bi-check-lg" aria-hidden="true"></i>';
+					btn.setAttribute('aria-label', T.copied);
+					clearTimeout(resetTimer);
+					resetTimer = setTimeout(function () {
+						btn.classList.remove('is-copied');
+						btn.innerHTML = '<i class="bi bi-clipboard" aria-hidden="true"></i>';
+						btn.setAttribute('aria-label', T.copyCode);
+					}, 1800);
+				}).catch(function () {});
+			});
+
+			wrap.appendChild(btn);
+		}
+
+		var pres = document.querySelectorAll('.content pre, .tab-panel pre');
+		Array.prototype.forEach.call(pres, enhance);
+	})();
+
+	/* --------------------------------------------------------
+	   Reading progress bar — tracks scroll position over the page.
+	   Only shown when there's article content to read.
+	   -------------------------------------------------------- */
+	(function () {
+		if (!document.querySelector('.content')) return;
+
+		var bar = document.createElement('div');
+		bar.className = 'reading-progress';
+		bar.setAttribute('role', 'progressbar');
+		bar.setAttribute('aria-hidden', 'true');
+		var fill = document.createElement('div');
+		fill.className = 'reading-progress-fill';
+		bar.appendChild(fill);
+		document.body.appendChild(bar);
+
+		var ticking = false;
+		function update() {
+			var h = document.documentElement;
+			var max = h.scrollHeight - h.clientHeight;
+			var pct = max > 0 ? (h.scrollTop / max) * 100 : 0;
+			fill.style.width = pct + '%';
+			ticking = false;
+		}
+		function onScroll() {
+			if (!ticking) {
+				ticking = true;
+				window.requestAnimationFrame(update);
+			}
+		}
+		window.addEventListener('scroll', onScroll, { passive: true });
+		window.addEventListener('resize', onScroll, { passive: true });
+		update();
+	})();
+
+	/* --------------------------------------------------------
+	   Back-to-top button — appears after scrolling down.
+	   -------------------------------------------------------- */
+	(function () {
+		var btn = document.createElement('button');
+		btn.type = 'button';
+		btn.className = 'back-to-top';
+		btn.setAttribute('aria-label', T.backToTop);
+		btn.innerHTML = '<i class="bi bi-arrow-up" aria-hidden="true"></i>';
+		document.body.appendChild(btn);
+
+		btn.addEventListener('click', function () {
+			var reduce = window.matchMedia &&
+				window.matchMedia('(prefers-reduced-motion: reduce)').matches;
+			window.scrollTo({ top: 0, behavior: reduce ? 'auto' : 'smooth' });
+		});
+
+		var ticking = false;
+		function update() {
+			btn.classList.toggle('is-visible', (window.scrollY || window.pageYOffset) > 400);
+			ticking = false;
+		}
+		window.addEventListener('scroll', function () {
+			if (!ticking) {
+				ticking = true;
+				window.requestAnimationFrame(update);
+			}
+		}, { passive: true });
+		update();
+	})();
+
+})();
diff --git a/languages/en.json b/languages/en.json
index a6514b8..9fc5994 100644
--- a/languages/en.json
+++ b/languages/en.json
@@ -5,5 +5,16 @@
 		"description": "A Bludit theme inspired by the Blowfish Hugo theme. Right sidebar, reading time, a light/dark mode toggle and a navbar with social icons and static pages."
 	},
 	"Toggle theme": "Toggle theme",
-	"Author": "Author"
+	"Author": "Author",
+	"Skip to content": "Skip to content",
+	"Copy": "Copy",
+	"Copied": "Copied",
+	"Copy code": "Copy code",
+	"Back to top": "Back to top",
+	"Previous slide": "Previous slide",
+	"Next slide": "Next slide",
+	"Go to slide": "Go to slide",
+	"Previous image": "Previous image",
+	"Next image": "Next image",
+	"Image viewer": "Image viewer"
 }
diff --git a/php/head.php b/php/head.php
index 8f89c81..8fa3cc4 100644
--- a/php/head.php
+++ b/php/head.php
@@ -2,6 +2,20 @@
 <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
 <meta name="generator" content="Bludit">
 
+<!-- Tint the mobile browser chrome to match the navbar (--chrome-bg per theme).
+     Set server-side from the theme cookie so it's correct on the first paint. -->
+<?php
+	$blowditChromeColors = array(
+		'light'      => '#1f1f1f',
+		'dark'       => '#1f1f1f',
+		'nord'       => '#3b4252',
+		'dracula'    => '#343746',
+		'catppuccin' => '#313244',
+	);
+	$blowditChrome = isset($blowditChromeColors[$blowditTheme]) ? $blowditChromeColors[$blowditTheme] : '#1f1f1f';
+?>
+<meta name="theme-color" content="<?php echo $blowditChrome; ?>">
+
 <!-- Set the colour theme as early as possible to avoid a white flash.
      Sets data-theme AND paints the html background/color-scheme inline, so the
      very first frame (before style.css loads) already uses the theme colour. -->
@@ -36,6 +50,113 @@
 <!-- Dynamic description tag -->
 <?php echo Theme::metaTags('description'); ?>
 
+<?php
+	// ---- Social sharing metadata (Open Graph + Twitter Card) ----
+	// $blowditIsArticle is pre-computed in index.php before this file is included.
+	$ogIsArticle = !empty($blowditIsArticle);
+
+	// ISO 8601 publish date — formatted explicitly so it's valid regardless of
+	// the admin's configured date format. Falls back to dateRaw() if Date is unavailable.
+	if (!function_exists('blowdit_iso_date')) {
+		function blowdit_iso_date($page, $field) {
+			$raw = $page->getValue($field);
+			if (!$raw) { return ''; }
+			if (class_exists('Date')) {
+				$fmt = Date::format($raw, DB_DATE_FORMAT, 'c');
+				if ($fmt) { return $fmt; }
+			}
+			return $raw;
+		}
+	}
+
+	if ($ogIsArticle) {
+		$ogTitle = $page->title();
+		$ogDesc  = $page->description();
+		$ogUrl   = $page->permalink(true);
+		$ogImage = $page->coverImage(true);
+		$ogPublishedIso = blowdit_iso_date($page, 'date');
+	} else {
+		$ogTitle = $site->title();
+		$ogDesc  = '';
+		$ogUrl   = Theme::siteUrl();
+		$ogImage = '';
+	}
+	// Fallbacks
+	if (!$ogDesc)  { $ogDesc  = $site->description() ?: $site->slogan(); }
+	if (!$ogImage) { $ogImage = DOMAIN_THEME . 'img/spleenftw.jpeg'; }
+
+	$ogType     = $ogIsArticle ? 'article' : 'website';
+	$ogSiteName = $site->title();
+?>
+<!-- Open Graph -->
+<meta property="og:type" content="<?php echo htmlspecialchars($ogType, ENT_QUOTES, 'UTF-8'); ?>">
+<meta property="og:site_name" content="<?php echo htmlspecialchars($ogSiteName, ENT_QUOTES, 'UTF-8'); ?>">
+<meta property="og:title" content="<?php echo htmlspecialchars($ogTitle, ENT_QUOTES, 'UTF-8'); ?>">
+<meta property="og:description" content="<?php echo htmlspecialchars($ogDesc, ENT_QUOTES, 'UTF-8'); ?>">
+<meta property="og:url" content="<?php echo htmlspecialchars($ogUrl, ENT_QUOTES, 'UTF-8'); ?>">
+<meta property="og:image" content="<?php echo htmlspecialchars($ogImage, ENT_QUOTES, 'UTF-8'); ?>">
+<?php if ($ogIsArticle): ?>
+<meta property="article:published_time" content="<?php echo htmlspecialchars($ogPublishedIso, ENT_QUOTES, 'UTF-8'); ?>">
+<meta property="article:author" content="<?php echo htmlspecialchars($page->username(), ENT_QUOTES, 'UTF-8'); ?>">
+<?php endif ?>
+<!-- Twitter Card -->
+<meta name="twitter:card" content="summary_large_image">
+<meta name="twitter:title" content="<?php echo htmlspecialchars($ogTitle, ENT_QUOTES, 'UTF-8'); ?>">
+<meta name="twitter:description" content="<?php echo htmlspecialchars($ogDesc, ENT_QUOTES, 'UTF-8'); ?>">
+<meta name="twitter:image" content="<?php echo htmlspecialchars($ogImage, ENT_QUOTES, 'UTF-8'); ?>">
+
+<?php
+	// ---- JSON-LD structured data (BlogPosting) — articles only ----
+	if ($ogIsArticle) {
+		$ldDescription = $page->description() ?: ($site->description() ?: $site->slogan());
+		$ldImage       = $page->coverImage(true) ?: (DOMAIN_THEME . 'img/spleenftw.jpeg');
+		$ldPublished   = $ogPublishedIso;
+
+		// dateModified: fall back to published date when not tracked.
+		$ldModified = blowdit_iso_date($page, 'dateModified');
+		if (!$ldModified) { $ldModified = $ldPublished; }
+
+		// timeRequired as an ISO 8601 duration (e.g. "PT8M") parsed from readingTime().
+		$ldTimeRequired = '';
+		if (preg_match('/\d+/', $page->readingTime(), $rtMatch)) {
+			$ldTimeRequired = 'PT' . $rtMatch[0] . 'M';
+		}
+
+		$jsonLd = array(
+			'@context' => 'https://schema.org',
+			'@type'    => 'BlogPosting',
+			'headline' => $page->title(),
+			'description' => $ldDescription,
+			'image'    => $ldImage,
+			'datePublished' => $ldPublished,
+			'dateModified'  => $ldModified,
+			'author'   => array(
+				'@type' => 'Person',
+				'name'  => $page->username(),
+				'url'   => Theme::siteUrl(),
+			),
+			'publisher' => array(
+				'@type' => 'Organization',
+				'name'  => $site->title(),
+				'logo'  => array(
+					'@type' => 'ImageObject',
+					'url'   => DOMAIN_THEME . 'img/favicon.png',
+				),
+			),
+			'mainEntityOfPage' => array(
+				'@type' => 'WebPage',
+				'@id'   => $page->permalink(true),
+			),
+			'wordCount' => str_word_count(strip_tags($page->content())),
+		);
+		if ($ldTimeRequired) { $jsonLd['timeRequired'] = $ldTimeRequired; }
+
+		echo '<script type="application/ld+json">'
+			. json_encode($jsonLd, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE)
+			. '</script>' . "\n";
+	}
+?>
+
 <!-- Include Favicon -->
 <?php echo Theme::favicon('img/favicon.png'); ?>