removing author and cleaning js / css

assets/scripts/ui/toc-active-link.js

@@ -0,0 +1,88 @@
+/* Event listener for scrolling and changing the active label on the TOC */
+document.addEventListener("DOMContentLoaded", () => {
+    const toc = document.querySelector("#text-table-of-contents");
+    if (!toc) { console.warn("No #text-table-of-contents found"); return; }
+
+    const links = toc.querySelectorAll('a[href^="#"]'); // '^=' is a starts with operator.
+    // <a href="#introduction">Intro</a>   matches  
+    if (!links.length) { console.warn("No ToC links found"); return; }
+
+    // Map: id -> link
+    const linkById = new Map();
+    links.forEach(a => {
+	const id = decodeURIComponent(a.getAttribute("href").slice(1));
+	const el = document.getElementById(id);
+	if (el) linkById.set(id, a);
+    });
+    if (!linkById.size) { console.warn("No matching headings with IDs"); return; }
+
+    // Headings to observe (h2–h4 usually)
+    const headings = [...document.querySelectorAll("h2[id], h3[id], h4[id]")]
+	  .filter(h => linkById.has(h.id));
+
+    // Helper to mark active
+    const setActive = (id) => {
+	links.forEach(a => {
+	    const active = a.getAttribute("href") === `#${id}`;
+	    a.classList.toggle("is-active", active);
+	    if (active) a.setAttribute("aria-current", "true");
+	    else a.removeAttribute("aria-current");
+	});
+    };
+
+    // Calculate sticky header offset in px
+    const headerOffsetPx = 6.5 * parseFloat(getComputedStyle(document.documentElement).fontSize);
+
+    // Track visible headings (id -> distance from top)
+    const visible = new Map();
+
+    const observer = new IntersectionObserver((entries) => {
+	entries.forEach(entry => {
+	    const id = entry.target.id;
+	    if (entry.isIntersecting) {
+		// How far from the top (after header offset)
+		const dist = entry.target.getBoundingClientRect().top - headerOffsetPx;
+		visible.set(id, dist);
+	    } else {
+		visible.delete(id);
+	    }
+	});
+	
+	if (visible.size) {
+	    // Choose the heading closest to the top (>= -headerOffset)
+	    const topMost = [...visible.entries()]
+		  .sort((a,b) => Math.abs(a[1]) - Math.abs(b[1]))[0][0];
+	    setActive(topMost);
+	    // console.log("Active:", topMost, visible);
+	}
+    }, {
+	root: null,                                   // track relative to viewport
+	rootMargin: `-${headerOffsetPx}px 0px -70% 0px`,
+	threshold: [0, 0.01, 0.1]                     // fire as soon as it enters
+    });
+    
+    headings.forEach(h => observer.observe(h));
+
+    // Initial highlight (in case load mid‑page)
+    let bestId = null, bestDist = Infinity;
+    headings.forEach(h => {
+	const top = h.getBoundingClientRect().top - headerOffsetPx;
+	const dist = top < 0 ? Math.abs(top) : top + 1e6;
+	if (dist < bestDist) { bestDist = dist; bestId = h.id; }
+    });
+    if (bestId) setActive(bestId);
+    
+    // smooth-scroll ToC clicks
+    toc.addEventListener("click", (e) => {
+	const a = e.target.closest('a[href^="#"]');
+	if (!a) return;
+	const id = decodeURIComponent(a.hash.slice(1));
+	const el = document.getElementById(id);
+	if (!el) return;
+	e.preventDefault();
+	el.scrollIntoView({ behavior: "smooth", block: "start" });
+	el.setAttribute("tabindex", "-1");
+	el.focus({ preventScroll: true });
+	history.pushState(null, "", `#${id}`);
+    });
+});