Scroll Progress Indicators

*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --bg: #070a12;
  --text: #f0f4fb;
  --muted: #8a95a8;
  --accent: #86e8ff;
  --neon-purple: #ae52ff;
  --border: #263249;
}

html {
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", "SF Pro Display", system-ui, sans-serif;
}
body {
  overflow-x: hidden;
}

/* Top bar */
.progress-top {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  z-index: 100;
  background: rgba(255, 255, 255, 0.05);
}
.progress-top-fill {
  height: 100%;
  width: 100%;
  background: linear-gradient(90deg, var(--accent), var(--neon-purple));
  transform: scaleX(0);
  transform-origin: left;
  will-change: transform;
}

/* Circular indicator */
.progress-circle {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  z-index: 100;
  width: 48px;
  height: 48px;
}
.progress-circle svg {
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}
.progress-circle .track {
  fill: none;
  stroke: var(--border);
  stroke-width: 3;
}
.progress-circle .fill {
  fill: none;
  stroke: var(--accent);
  stroke-width: 3;
  stroke-linecap: round;
  stroke-dasharray: 125.66;
  stroke-dashoffset: 125.66;
  will-change: stroke-dashoffset;
  transition: stroke-dashoffset 0.05s linear;
}
.progress-pct {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.6rem;
  font-weight: 700;
  color: var(--accent);
}

/* Section dots */
.section-dots {
  position: fixed;
  right: 2rem;
  top: 50%;
  transform: translateY(-50%);
  z-index: 100;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}
.dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--border);
  border: none;
  cursor: pointer;
  transition: background 0.3s, box-shadow 0.3s, transform 0.3s;
}
.dot:hover {
  background: rgba(134, 232, 255, 0.4);
}
.dot.active {
  background: var(--accent);
  box-shadow: 0 0 10px rgba(134, 232, 255, 0.4);
  transform: scale(1.3);
}

/* Sections */
.section {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4rem 2rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.03);
}

.content {
  max-width: 600px;
}

.eyebrow {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.18em;
  color: var(--accent);
  margin-bottom: 1rem;
}

h1 {
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  background: linear-gradient(135deg, #fff, var(--accent));
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 1rem;
}

h2 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

.body-text {
  font-size: 1rem;
  color: var(--muted);
  line-height: 1.7;
  margin-bottom: 1rem;
}
code {
  background: rgba(134, 232, 255, 0.1);
  color: var(--accent);
  padding: 0.12rem 0.4rem;
  border-radius: 4px;
  font-size: 0.85rem;
}

.btn-back {
  display: inline-block;
  margin-top: 1.5rem;
  padding: 0.7rem 2rem;
  border-radius: 999px;
  border: 1px solid rgba(134, 232, 255, 0.3);
  color: var(--accent);
  text-decoration: none;
  font: 600 0.85rem / 1 "Inter", system-ui, sans-serif;
  transition: all 0.25s;
}
.btn-back:hover {
  background: rgba(134, 232, 255, 0.08);
  border-color: var(--accent);
}

.reduced-motion .progress-top-fill {
  transition: none;
}
.reduced-motion .progress-circle .fill {
  transition: none;
}

@media (max-width: 640px) {
  .section-dots {
    right: 0.75rem;
  }
  .progress-circle {
    bottom: 1rem;
    right: 0.75rem;
    width: 40px;
    height: 40px;
  }
}

if (!window.MotionPreference) {
  const __mql = window.matchMedia("(prefers-reduced-motion: reduce)");
  const __listeners = new Set();

  const MotionPreference = {
    prefersReducedMotion() {
      return __mql.matches;
    },
    setOverride(value) {
      const reduced = Boolean(value);
      document.documentElement.classList.toggle("reduced-motion", reduced);
      window.dispatchEvent(new CustomEvent("motion-preference", { detail: { reduced } }));
      for (const listener of __listeners) {
        try {
          listener({ reduced, override: reduced, systemReduced: __mql.matches });
        } catch {}
      }
    },
    onChange(listener) {
      __listeners.add(listener);
      try {
        listener({
          reduced: __mql.matches,
          override: null,
          systemReduced: __mql.matches,
        });
      } catch {}
      return () => __listeners.delete(listener);
    },
    getState() {
      return { reduced: __mql.matches, override: null, systemReduced: __mql.matches };
    },
  };

  window.MotionPreference = MotionPreference;
}

function prefersReducedMotion() {
  return window.MotionPreference.prefersReducedMotion();
}

function initDemoShell() {
  // No-op shim in imported standalone snippets.
}

import gsap from "gsap";
import { ScrollTrigger } from "gsap/ScrollTrigger";
import Lenis from "lenis";

gsap.registerPlugin(ScrollTrigger);

initDemoShell({
  title: "Scroll Progress Indicators",
  category: "scroll",
  tech: ["gsap", "scrolltrigger", "svg"],
});

const lenis = new Lenis({ lerp: 0.1, smoothWheel: true });
lenis.on("scroll", ScrollTrigger.update);
gsap.ticker.add((time) => lenis.raf(time * 1000));
gsap.ticker.lagSmoothing(0);

const reduced = prefersReducedMotion();
if (reduced) document.documentElement.classList.add("reduced-motion");

// Refs
const topFill = document.querySelector(".progress-top-fill");
const circleFill = document.querySelector(".progress-circle .fill");
const pctText = document.getElementById("progress-pct");
const dots = document.querySelectorAll(".dot");
const sections = document.querySelectorAll(".section");
const circumference = 2 * Math.PI * 20; // r=20

// Overall page progress
ScrollTrigger.create({
  trigger: document.body,
  start: "top top",
  end: "bottom bottom",
  onUpdate: (self) => {
    const p = self.progress;

    // Top bar
    topFill.style.transform = `scaleX(${p})`;

    // Circle
    const offset = circumference * (1 - p);
    circleFill.style.strokeDashoffset = offset;

    // Percentage text
    pctText.textContent = `${Math.round(p * 100)}%`;
  },
});

// Per-section triggers for dots
sections.forEach((section, i) => {
  ScrollTrigger.create({
    trigger: section,
    start: "top center",
    end: "bottom center",
    onEnter: () => setActiveDot(i),
    onEnterBack: () => setActiveDot(i),
  });
});

function setActiveDot(index) {
  dots.forEach((d, i) => d.classList.toggle("active", i === index));
}

// Dot click → scroll to section
dots.forEach((dot) => {
  dot.addEventListener("click", () => {
    const idx = parseInt(dot.dataset.section, 10);
    const target = sections[idx];
    if (target) {
      lenis.scrollTo(target, { offset: 0, duration: 1.2 });
    }
  });
});

// Intro animation
if (!reduced) {
  gsap.set('.section[data-index="0"] .eyebrow', { opacity: 0, y: 20 });
  gsap.set('.section[data-index="0"] h1', { opacity: 0, y: 40 });
  gsap.set('.section[data-index="0"] .body-text', { opacity: 0, y: 25 });

  gsap
    .timeline({ defaults: { ease: "expo.out" } })
    .to('.section[data-index="0"] .eyebrow', { opacity: 1, y: 0, duration: 0.7, delay: 0.3 })
    .to('.section[data-index="0"] h1', { opacity: 1, y: 0, duration: 0.9 }, "-=0.4")
    .to('.section[data-index="0"] .body-text', { opacity: 1, y: 0, duration: 0.7 }, "-=0.5");
}

// Section content reveals
sections.forEach((section, i) => {
  if (i === 0) return;
  const h = section.querySelector("h2");
  const p = section.querySelector(".body-text");

  if (!reduced && h) {
    gsap.set(h, { opacity: 0, y: 40 });
    gsap.to(h, {
      opacity: 1,
      y: 0,
      duration: 0.8,
      ease: "expo.out",
      scrollTrigger: { trigger: section, start: "top 70%" },
    });
  }
  if (!reduced && p) {
    gsap.set(p, { opacity: 0, y: 25 });
    gsap.to(p, {
      opacity: 1,
      y: 0,
      duration: 0.7,
      ease: "expo.out",
      scrollTrigger: { trigger: section, start: "top 65%" },
    });
  }
});

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Scroll Progress Indicators — stealthisdesign</title>
  <link rel="stylesheet" href="style.css">
    <script type="importmap">{"imports":{"gsap":"https://esm.sh/[email protected]","gsap/ScrollTrigger":"https://esm.sh/[email protected]/ScrollTrigger","gsap/SplitText":"https://esm.sh/[email protected]/SplitText","gsap/Flip":"https://esm.sh/[email protected]/Flip","gsap/ScrambleTextPlugin":"https://esm.sh/[email protected]/ScrambleTextPlugin","gsap/TextPlugin":"https://esm.sh/[email protected]/TextPlugin","gsap/all":"https://esm.sh/[email protected]/all","gsap/":"https://esm.sh/[email protected]/","lenis":"https://esm.sh/[email protected]/dist/lenis.mjs","three":"https://esm.sh/[email protected]","three/addons/":"https://esm.sh/[email protected]/examples/jsm/"}}</script>
  <style>html.lenis,
html.lenis body {
  height: auto;
}

.lenis:not(.lenis-autoToggle).lenis-stopped {
  overflow: clip;
}

.lenis [data-lenis-prevent],
.lenis [data-lenis-prevent-wheel],
.lenis [data-lenis-prevent-touch] {
  overscroll-behavior: contain;
}

.lenis.lenis-smooth iframe {
  pointer-events: none;
}

.lenis.lenis-autoToggle {
  transition-property: overflow;
  transition-duration: 1ms;
  transition-behavior: allow-discrete;
}</style>
</head>
<body>
  <!-- Fixed indicators -->
  <div class="progress-top" id="progress-top"><div class="progress-top-fill"></div></div>

  <div class="progress-circle" id="progress-circle">
    <svg viewBox="0 0 48 48"><circle class="track" cx="24" cy="24" r="20"/><circle class="fill" cx="24" cy="24" r="20"/></svg>
    <span class="progress-pct" id="progress-pct">0%</span>
  </div>

  <nav class="section-dots" id="section-dots">
    <button class="dot active" data-section="0"></button>
    <button class="dot" data-section="1"></button>
    <button class="dot" data-section="2"></button>
    <button class="dot" data-section="3"></button>
    <button class="dot" data-section="4"></button>
  </nav>

  <!-- Content sections -->
  <section class="section" data-index="0">
    <div class="content">
      <span class="eyebrow">Demo 06</span>
      <h1>Scroll Progress Indicators</h1>
      <p class="body-text">Three indicator styles running simultaneously: top bar, circular SVG, and section dots. All driven by ScrollTrigger progress values.</p>
    </div>
  </section>

  <section class="section" data-index="1">
    <div class="content">
      <h2>Linear Bar</h2>
      <p class="body-text">The top progress bar uses <code>scaleX</code> driven by overall page scroll progress. It's the simplest indicator — a single CSS transform.</p>
    </div>
  </section>

  <section class="section" data-index="2">
    <div class="content">
      <h2>Circular SVG</h2>
      <p class="body-text">The circle uses SVG <code>stroke-dashoffset</code> to draw the ring progressively. The percentage text updates in real-time with scroll position.</p>
    </div>
  </section>

  <section class="section" data-index="3">
    <div class="content">
      <h2>Section Dots</h2>
      <p class="body-text">Each dot represents a content section. The active dot highlights based on which section's ScrollTrigger is currently in view. Click a dot to jump to that section.</p>
    </div>
  </section>

  <section class="section" data-index="4">
    <div class="content">
      <h2>Combined Power</h2>
      <p class="body-text">When used together, these indicators give users multiple spatial cues about their position in the content. Each serves a different cognitive need: linear for absolute progress, circular for at-a-glance percentage, dots for structural navigation.</p>
      <a href="/" class="btn-back">Back to Showcase</a>
    </div>
  </section>

  <script type="module" src="script.js"></script>
</body>
</html>