Pinned Scroll Sections

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

:root {
  --bg: #070a12;
  --panel: #121a2b;
  --border: #263249;
  --text: #f0f4fb;
  --muted: #8a95a8;
  --accent: #86e8ff;
  --neon-purple: #ae52ff;
  --neon-pink: #ff40d6;
}

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

body {
  overflow-x: hidden;
}

/* ── Intro ── */
.intro {
  min-height: 70vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 2rem;
}

.eyebrow {
  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, 6vw, 4rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  background: linear-gradient(135deg, #fff, var(--accent), var(--neon-purple));
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.subtitle {
  font-size: clamp(0.9rem, 2vw, 1.05rem);
  color: var(--muted);
  max-width: 500px;
  margin-top: 0.75rem;
  line-height: 1.6;
}

/* ── Pinned sections ── */
.pinned-section {
  position: relative;
  min-height: 100vh;
}

.pin-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  min-height: 100vh;
  gap: 2rem;
  padding: 0 4rem;
  align-items: center;
}

/* ── Left side: steps ── */
.pin-left {
  display: flex;
  gap: 2rem;
  align-items: flex-start;
  padding: 2rem 0;
}

.step-indicators {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  padding-top: 0.5rem;
}

.step-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--border);
  transition: background 0.4s ease, box-shadow 0.4s ease;
}

.step-dot.active {
  background: var(--accent);
  box-shadow: 0 0 12px rgba(134, 232, 255, 0.4);
}

.pin-text {
  position: relative;
}

.step-text {
  position: absolute;
  top: 0;
  left: 0;
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.4s ease, transform 0.4s ease;
  pointer-events: none;
}

.step-text.active {
  position: relative;
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.step-label {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent);
  margin-bottom: 0.75rem;
}

.step-text h2 {
  font-size: clamp(2rem, 4vw, 3.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.05;
  margin-bottom: 1rem;
  -webkit-text-fill-color: var(--text);
}

.step-text p {
  font-size: 1rem;
  color: var(--muted);
  line-height: 1.7;
  max-width: 400px;
}

/* ── Right side: visuals ── */
.pin-right {
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Visual stage (section 1) */
.visual-stage {
  position: relative;
  width: 360px;
  height: 360px;
}

.vis-element {
  position: absolute;
  will-change: transform, opacity;
}

.vis-circle {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), rgba(134, 232, 255, 0.3));
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  opacity: 0;
}

.vis-square {
  width: 80px;
  height: 80px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--neon-purple), rgba(174, 82, 255, 0.3));
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  opacity: 0;
}

.vis-triangle {
  width: 0;
  height: 0;
  border-left: 45px solid transparent;
  border-right: 45px solid transparent;
  border-bottom: 78px solid var(--neon-pink);
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  opacity: 0;
  filter: drop-shadow(0 0 16px rgba(255, 64, 214, 0.3));
}

.vis-line {
  position: absolute;
  height: 2px;
  background: var(--border);
  border-radius: 1px;
  opacity: 0;
  will-change: transform, opacity;
}

.vis-line-1 {
  width: 120px;
  top: 30%;
  left: 10%;
}
.vis-line-2 {
  width: 80px;
  top: 60%;
  right: 10%;
}
.vis-line-3 {
  width: 160px;
  bottom: 20%;
  left: 25%;
}

/* Metric bars (section 2) */
.metric-bars {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  width: 100%;
  max-width: 360px;
}

.metric-bar {
  position: relative;
}

.bar-fill {
  height: 8px;
  border-radius: 4px;
  background: var(--color, var(--accent));
  width: 0%;
  will-change: width;
  transition: width 0.05s linear;
}

.bar-label {
  display: block;
  margin-top: 0.5rem;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

/* ── Outro ── */
.outro {
  min-height: 50vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 2rem;
}

.outro h2 {
  font-size: clamp(1.8rem, 4vw, 3rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 1.5rem;
  -webkit-text-fill-color: var(--text);
}

.btn-back {
  display: inline-block;
  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 ease;
}

.btn-back:hover {
  background: rgba(134, 232, 255, 0.08);
  border-color: var(--accent);
}

/* ── Reduced motion ── */
.reduced-motion .vis-element,
.reduced-motion .vis-line,
.reduced-motion .step-text {
  opacity: 1 !important;
  transform: none !important;
}

.reduced-motion .bar-fill {
  transition: none;
}

@media (max-width: 768px) {
  .pin-content {
    grid-template-columns: 1fr;
    padding: 0 1.5rem;
  }

  .pin-right {
    min-height: 300px;
  }
  .visual-stage {
    width: 260px;
    height: 260px;
  }
}

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);

// ── Demo shell ──
initDemoShell({
  title: "Pinned Scroll Sections",
  category: "scroll",
  tech: ["gsap", "scrolltrigger", "pin"],
});

// ── Lenis ──
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");

window.addEventListener("motion-preference", (e) => {
  document.documentElement.classList.toggle("reduced-motion", e.detail.reduced);
  ScrollTrigger.refresh();
});

const dur = (d) => (reduced ? 0 : d);

// ── Helper: update step text + dots ──
function setActiveStep(section, stepIndex) {
  const dots = section.querySelectorAll(".step-dot");
  const texts = section.querySelectorAll(".step-text");

  dots.forEach((dot, i) => dot.classList.toggle("active", i === stepIndex));
  texts.forEach((text, i) => text.classList.toggle("active", i === stepIndex));
}

// ══════════════════════════════════════════════════
// Section 1: Features (Design / Animate / Polish)
// ══════════════════════════════════════════════════

const s1 = document.getElementById("section-features");

const tl1 = gsap.timeline({
  scrollTrigger: {
    trigger: s1,
    pin: true,
    scrub: 1,
    start: "top top",
    end: "+=300%",
  },
});

// Step 0 → 1 transition (Design → Animate)
tl1
  // Step 0: Circle appears
  .to("#vis-circle", { opacity: 1, scale: 1, duration: dur(0.3) }, 0)
  .to(".vis-line-1", { opacity: 1, duration: dur(0.2) }, 0.05)
  // Step 0 → 1: Circle moves, square enters
  .call(() => setActiveStep(s1, 1), [], 0.33)
  .to("#vis-circle", { x: -80, y: -60, scale: 0.8, duration: dur(0.3) }, 0.33)
  .to("#vis-square", { opacity: 1, scale: 1, rotation: 45, duration: dur(0.3) }, 0.33)
  .to(".vis-line-1", { scaleX: 1.5, x: -20, background: "var(--accent)", duration: dur(0.2) }, 0.35)
  .to(".vis-line-2", { opacity: 1, duration: dur(0.2) }, 0.38)
  // Step 1 → 2: All elements arrange, triangle enters
  .call(() => setActiveStep(s1, 2), [], 0.66)
  .to("#vis-circle", { x: -100, y: -80, scale: 0.65, duration: dur(0.3) }, 0.66)
  .to("#vis-square", { x: 80, y: -50, rotation: 90, scale: 0.7, duration: dur(0.3) }, 0.66)
  .to("#vis-triangle", { opacity: 1, y: 60, duration: dur(0.3) }, 0.66)
  .to(".vis-line-3", { opacity: 1, duration: dur(0.2) }, 0.7)
  .to(
    [".vis-line-1", ".vis-line-2", ".vis-line-3"],
    {
      background: "var(--accent)",
      opacity: 0.6,
      duration: dur(0.2),
    },
    0.72
  );

// Initialize step 0
setActiveStep(s1, 0);

// ══════════════════════════════════════════════════
// Section 2: Metrics (Performance / Accessibility / Bundle)
// ══════════════════════════════════════════════════

const s2 = document.getElementById("section-metrics");
const bar1 = s2.querySelector("#bar-1 .bar-fill");
const bar2 = s2.querySelector("#bar-2 .bar-fill");
const bar3 = s2.querySelector("#bar-3 .bar-fill");

const tl2 = gsap.timeline({
  scrollTrigger: {
    trigger: s2,
    pin: true,
    scrub: 1,
    start: "top top",
    end: "+=300%",
    onUpdate: (self) => {
      const p = self.progress;

      // Bar 1 fills in step 0 (0–0.33)
      const b1 = gsap.utils.clamp(0, 1, p / 0.33);
      bar1.style.width = `${b1 * 95}%`;

      // Bar 2 fills in step 1 (0.33–0.66)
      const b2 = gsap.utils.clamp(0, 1, (p - 0.33) / 0.33);
      bar2.style.width = `${b2 * 100}%`;

      // Bar 3 fills in step 2 (0.66–1)
      const b3 = gsap.utils.clamp(0, 1, (p - 0.66) / 0.34);
      bar3.style.width = `${b3 * 88}%`;

      // Step indicators
      if (p < 0.33) setActiveStep(s2, 0);
      else if (p < 0.66) setActiveStep(s2, 1);
      else setActiveStep(s2, 2);
    },
  },
});

setActiveStep(s2, 0);

// ── Intro animations ──
if (!reduced) {
  gsap.set(".intro .eyebrow", { opacity: 0, y: 20 });
  gsap.set(".intro h1", { opacity: 0, y: 40 });
  gsap.set(".intro .subtitle", { opacity: 0, y: 25 });

  gsap
    .timeline({ defaults: { ease: "expo.out" } })
    .to(".intro .eyebrow", { opacity: 1, y: 0, duration: 0.7, delay: 0.3 })
    .to(".intro h1", { opacity: 1, y: 0, duration: 0.9 }, "-=0.4")
    .to(".intro .subtitle", { opacity: 1, y: 0, duration: 0.7 }, "-=0.5");
}

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Pinned Scroll Sections — 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>
  <!-- Intro -->
  <section class="intro">
    <span class="eyebrow">Demo 04</span>
    <h1>Pinned Scroll Sections</h1>
    <p class="subtitle">Each section pins in place while a multi-step timeline plays, driven entirely by scroll position.</p>
  </section>

  <!-- Pinned Section 1: Features -->
  <section class="pinned-section" id="section-features">
    <div class="pin-content">
      <div class="pin-left">
        <div class="step-indicators">
          <div class="step-dot active" data-step="0"></div>
          <div class="step-dot" data-step="1"></div>
          <div class="step-dot" data-step="2"></div>
        </div>
        <div class="pin-text">
          <div class="step-text active" data-step="0">
            <span class="step-label">Step 1 of 3</span>
            <h2>Design</h2>
            <p>Every animation begins with intention. The design phase establishes timing, easing, and choreography before a single line of code is written.</p>
          </div>
          <div class="step-text" data-step="1">
            <span class="step-label">Step 2 of 3</span>
            <h2>Animate</h2>
            <p>ScrollTrigger scrubs through GSAP timelines at the pace of the user's scroll, creating a sense of direct manipulation and control.</p>
          </div>
          <div class="step-text" data-step="2">
            <span class="step-label">Step 3 of 3</span>
            <h2>Polish</h2>
            <p>The final pass adds micro-interactions, easing refinements, and reduced-motion alternatives to ensure a premium experience for everyone.</p>
          </div>
        </div>
      </div>
      <div class="pin-right">
        <div class="visual-stage">
          <div class="vis-element vis-circle" id="vis-circle"></div>
          <div class="vis-element vis-square" id="vis-square"></div>
          <div class="vis-element vis-triangle" id="vis-triangle"></div>
          <div class="vis-line vis-line-1"></div>
          <div class="vis-line vis-line-2"></div>
          <div class="vis-line vis-line-3"></div>
        </div>
      </div>
    </div>
  </section>

  <!-- Pinned Section 2: Metrics -->
  <section class="pinned-section" id="section-metrics">
    <div class="pin-content">
      <div class="pin-left">
        <div class="step-indicators">
          <div class="step-dot active" data-step="0"></div>
          <div class="step-dot" data-step="1"></div>
          <div class="step-dot" data-step="2"></div>
        </div>
        <div class="pin-text">
          <div class="step-text active" data-step="0">
            <span class="step-label">Performance</span>
            <h2>60fps</h2>
            <p>Every animation targets a smooth 60 frames per second, with GPU-accelerated transforms and careful paint avoidance.</p>
          </div>
          <div class="step-text" data-step="1">
            <span class="step-label">Accessibility</span>
            <h2>100%</h2>
            <p>All demos respect prefers-reduced-motion, include keyboard navigation, and maintain WCAG AA contrast ratios.</p>
          </div>
          <div class="step-text" data-step="2">
            <span class="step-label">Bundle Size</span>
            <h2>&lt;50kb</h2>
            <p>Tree-shaking and careful dependency management keep animation code lean and loading times fast.</p>
          </div>
        </div>
      </div>
      <div class="pin-right">
        <div class="metric-bars">
          <div class="metric-bar" id="bar-1">
            <div class="bar-fill" style="--color: #86e8ff;"></div>
            <span class="bar-label">Performance</span>
          </div>
          <div class="metric-bar" id="bar-2">
            <div class="bar-fill" style="--color: #ae52ff;"></div>
            <span class="bar-label">Accessibility</span>
          </div>
          <div class="metric-bar" id="bar-3">
            <div class="bar-fill" style="--color: #ff40d6;"></div>
            <span class="bar-label">Efficiency</span>
          </div>
        </div>
      </div>
    </div>
  </section>

  <!-- Outro -->
  <section class="outro">
    <h2>Scroll-driven storytelling.</h2>
    <a href="/" class="btn-back">Back to Showcase</a>
  </section>

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