Before / after slider

<div class="motion-demo motion-demo--before-after-slider" data-motion="before-after-slider" aria-label="Before / after slider demo">
  <figure class="motion-comparison" data-comparison><div class="motion-before">Before</div><div class="motion-after" data-comparison-after>After</div><span class="motion-divider" data-comparison-divider aria-hidden="true"></span><input class="motion-comparison-control" type="range" min="0" max="100" step="1" value="50" aria-label="Before and after divider position" data-comparison-input></figure>
</div>

.motion-demo.motion-demo--before-after-slider {
  box-sizing: border-box;
  position: relative;
  display: grid;
  place-items: center;
  width: min(100%, 34rem);
  min-height: 15rem;
  padding: 2rem;
  overflow: hidden;
  color: #18181b;
  background: #fafafa;
  border: 1px solid #e4e4e7;
  border-radius: 16px;
  isolation: isolate;
}

.motion-demo.motion-demo--before-after-slider *, .motion-demo.motion-demo--before-after-slider *::before, .motion-demo.motion-demo--before-after-slider *::after {
  box-sizing: border-box;
}

.motion-demo.motion-demo--before-after-slider .motion-surface {
  position: relative;
  display: grid;
  gap: 0.65rem;
  width: min(100%, 18rem);
  padding: 1.25rem;
  background: #ffffff;
  border: 1px solid #e4e4e7;
  border-radius: 16px;
  box-shadow: none;
}

.motion-demo.motion-demo--before-after-slider .motion-surface strong { font-weight: 500; }

.motion-demo.motion-demo--before-after-slider .motion-line {
  display: block;
  width: 100%;
  height: 0.5rem;
  background: #e4e4e7;
  border-radius: 999px;
}

.motion-demo.motion-demo--before-after-slider .motion-line:last-child { width: 62%; }

.motion-demo.motion-demo--before-after-slider .motion-button {
  position: relative;
  min-height: 2.75rem;
  padding: 0.75rem 1.1rem;
  color: white;
  font: inherit;
  font-weight: 700;
  background: #18181b;
  border: 0;
  border-radius: 999px;
  cursor: pointer;
}

.motion-demo.motion-demo--before-after-slider .motion-button:focus-visible { outline: 3px solid rgb(37 99 235 / 32%); outline-offset: 3px; }

.motion-demo.motion-demo--before-after-slider .motion-action-row {
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  margin-top: 0.85rem;
}

.motion-demo.motion-demo--before-after-slider .motion-replay-scene {
  width: min(100%, 22rem);
  display: grid;
  place-items: center;
}

.motion-demo.motion-demo--before-after-slider .motion-pausable-scene {
  width: min(100%, 22rem);
  display: grid;
  place-items: center;
}

.motion-demo.motion-demo--before-after-slider button.motion-surface {
  color: inherit;
  font: inherit;
  text-align: start;
  cursor: pointer;
}

.motion-demo.motion-demo--before-after-slider .motion-replay-button,
.motion-demo.motion-demo--before-after-slider .motion-undo-button,
.motion-demo.motion-demo--before-after-slider .motion-dismiss-button,
.motion-demo.motion-demo--before-after-slider .motion-pause-button {
  min-height: 2.75rem;
  padding: 0.65rem 0.9rem;
  color: #18181b;
  font: 650 0.78rem/1 ui-sans-serif, system-ui, sans-serif;
  background: #ffffff;
  border: 1px solid #d4d4d8;
  border-radius: 8px;
  cursor: pointer;
}

.motion-demo.motion-demo--before-after-slider .motion-replay-button:focus-visible,
.motion-demo.motion-demo--before-after-slider .motion-undo-button:focus-visible,
.motion-demo.motion-demo--before-after-slider .motion-dismiss-button:focus-visible,
.motion-demo.motion-demo--before-after-slider .motion-pause-button:focus-visible,
.motion-demo.motion-demo--before-after-slider [data-reorder-item]:focus-visible,
.motion-demo.motion-demo--before-after-slider [data-swipe-target]:focus-visible {
  outline: 3px solid rgb(37 99 235 / 32%);
  outline-offset: 3px;
}

.motion-demo.motion-demo--before-after-slider .motion-status {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.motion-demo.motion-demo--before-after-slider .motion-ripple-ink {
  position: absolute;
  width: 12px;
  height: 12px;
  pointer-events: none;
  background: rgb(255 255 255 / 72%);
  border-radius: 50%;
  transform: translate(-50%, -50%) scale(0.95);
  opacity: 0;
}

.motion-demo.motion-demo--before-after-slider .motion-state-stack { position: relative; width: min(100%, 18rem); height: 9rem; }
.motion-demo.motion-demo--before-after-slider .motion-state { position: absolute; inset: 0; display: grid; place-items: center; padding: 1rem; background: #ffffff; border: 1px solid #e4e4e7; border-radius: 16px; }
.motion-demo.motion-demo--before-after-slider .motion-state--to { background: #18181b; color: white; }

.motion-demo.motion-demo--before-after-slider .motion-scroll-track > span { color: #71717a; font: 600 0.72rem/1.2 ui-monospace, monospace; letter-spacing: 0.08em; text-transform: uppercase; }
.motion-demo.motion-demo--before-after-slider .motion-orbit-item { display: grid; place-items: center; width: 2.5rem; height: 2.5rem; color: white; background: #2563eb; border-radius: 50%; }
.motion-demo.motion-demo--before-after-slider .motion-text-stack { position: relative; width: min(100%, 18rem); min-height: 4rem; }
.motion-demo.motion-demo--before-after-slider svg { width: min(100%, 20rem); height: auto; }

.motion-demo.motion-demo--before-after-slider .motion-comparison { position: relative; width: min(100%, 22rem); aspect-ratio: 16 / 9; overflow: hidden; border-radius: 16px; background: #52525b; }
.motion-demo.motion-demo--before-after-slider .motion-before, .motion-demo.motion-demo--before-after-slider .motion-after { position: absolute; inset: 0; display: grid; place-items: center; color: white; }
.motion-demo.motion-demo--before-after-slider .motion-after { overflow: hidden; background: #2563eb; clip-path: inset(0 50% 0 0); }
.motion-demo.motion-demo--before-after-slider .motion-divider { position: absolute; inset: 0 auto 0 50%; width: 2px; pointer-events: none; background: white; box-shadow: 0 0 0 1px rgb(0 0 0 / 18%); transform: translate3d(-1px, 0, 0); }
.motion-demo.motion-demo--before-after-slider .motion-divider::after { content: "↔"; position: absolute; top: 50%; left: 50%; width: 2.25rem; height: 2.25rem; display: grid; place-items: center; color: #18181b; background: white; border-radius: 50%; transform: translate(-50%, -50%); box-shadow: 0 2px 8px rgb(0 0 0 / 18%); }
.motion-demo.motion-demo--before-after-slider .motion-comparison-control { position: absolute; inset: 0; z-index: 2; width: 100%; height: 100%; margin: 0; cursor: ew-resize; opacity: 0; }

@keyframes motion-before-after-slider-reduced-fade {
  from { opacity: 0.84; }
  to { opacity: 1; }
}

.force-reduced-motion .motion-demo.motion-demo--before-after-slider {
  animation: motion-before-after-slider-reduced-fade 160ms cubic-bezier(0.23, 1, 0.32, 1) both !important;
}

.force-reduced-motion .motion-demo.motion-demo--before-after-slider *,
.force-reduced-motion .motion-demo.motion-demo--before-after-slider *::before,
.force-reduced-motion .motion-demo.motion-demo--before-after-slider *::after {
  animation: none !important;
  animation-delay: 0ms !important;
  animation-iteration-count: 1 !important;
  transition-property: opacity, color, background-color, border-color !important;
  transition-duration: 160ms !important;
  transition-delay: 0ms !important;
  scroll-behavior: auto !important;
}

.force-reduced-motion .motion-demo.motion-demo--before-after-slider .motion-button,
.force-reduced-motion .motion-demo.motion-demo--before-after-slider [data-reorder-item],
.force-reduced-motion .motion-demo.motion-demo--before-after-slider [data-swipe-target],
.force-reduced-motion .motion-demo.motion-demo--before-after-slider [data-spring-target] {
  transform: none !important;
}

.force-reduced-motion .motion-demo.motion-demo--before-after-slider .motion-path { stroke-dashoffset: 0 !important; }
.force-reduced-motion .motion-demo.motion-demo--before-after-slider .motion-word--from { opacity: 0 !important; visibility: hidden; }
.force-reduced-motion .motion-demo.motion-demo--before-after-slider .motion-word:not(.motion-word--from) { opacity: 1 !important; filter: none !important; transform: none !important; }

@media (prefers-reduced-motion: reduce) {
  .motion-demo.motion-demo--before-after-slider {
    animation: motion-before-after-slider-reduced-fade 160ms cubic-bezier(0.23, 1, 0.32, 1) both !important;
  }

  .motion-demo.motion-demo--before-after-slider *, .motion-demo.motion-demo--before-after-slider *::before, .motion-demo.motion-demo--before-after-slider *::after {
    animation: none !important;
    animation-delay: 0ms !important;
    animation-iteration-count: 1 !important;
    transition-property: opacity, color, background-color, border-color !important;
    transition-duration: 160ms !important;
    transition-delay: 0ms !important;
    scroll-behavior: auto !important;
  }

  .motion-demo.motion-demo--before-after-slider .motion-button,
  .motion-demo.motion-demo--before-after-slider [data-reorder-item],
  .motion-demo.motion-demo--before-after-slider [data-swipe-target],
  .motion-demo.motion-demo--before-after-slider [data-spring-target] {
    transform: none !important;
  }

  .motion-demo.motion-demo--before-after-slider .motion-path { stroke-dashoffset: 0 !important; }
  .motion-demo.motion-demo--before-after-slider .motion-word--from { opacity: 0 !important; visibility: hidden; }
  .motion-demo.motion-demo--before-after-slider .motion-word:not(.motion-word--from) { opacity: 1 !important; filter: none !important; transform: none !important; }
}

(() => {
  const config = {
  "id": "before-after-slider",
  "duration": 180,
  "distance": 72,
  "resistance": 65,
  "position": 50,
  "stiffness": 220,
  "damping": 24,
  "mass": 1,
  "velocity": 0,
  "rippleSize": 220,
  "rippleOpacity": 24,
  "dragScale": 103,
  "autoplay": false
};
  const mount = (root, config) => {

    const cleanups = [];
    const addCleanup = (callback) => cleanups.push(callback);
    const cleanup = () => {
      for (let index = cleanups.length - 1; index >= 0; index -= 1) {
        try { cleanups[index](); } catch { /* keep cleanup reentrant */ }
      }
      cleanups.length = 0;
    };
    const on = (target, type, listener, options) => {
      target.addEventListener(type, listener, options);
      addCleanup(() => target.removeEventListener(type, listener, options));
    };
    const reduced = () => root.closest(".force-reduced-motion") !== null ||
      window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    const watchReduced = (callback) => {
      const media = window.matchMedia("(prefers-reduced-motion: reduce)");
      const notify = () => callback(reduced());
      media.addEventListener("change", notify);
      const observer = typeof MutationObserver === "undefined" ? null : new MutationObserver(notify);
      let ancestor = root;
      while (observer && ancestor) {
        observer.observe(ancestor, { attributes: true, attributeFilter: ["class"] });
        ancestor = ancestor.parentElement;
      }
      addCleanup(() => {
        media.removeEventListener("change", notify);
        if (observer) observer.disconnect();
      });
    };

    const comparison = root.querySelector("[data-comparison]");
    const after = root.querySelector("[data-comparison-after]");
    const divider = root.querySelector("[data-comparison-divider]");
    const input = root.querySelector("[data-comparison-input]");
    if (!comparison || !after || !divider || !input) return cleanup;
    const initial = {
      value: input.value,
      clipPath: after.style.clipPath,
      insetInlineStart: divider.style.insetInlineStart,
      transform: divider.style.transform,
      valueText: input.getAttribute("aria-valuetext")
    };
    const update = () => {
      const value = Math.min(100, Math.max(0, Number(input.value || config.position)));
      after.style.clipPath = "inset(0 " + String(100 - value) + "% 0 0)";
      divider.style.insetInlineStart = String(value) + "%";
      divider.style.transform = "translate3d(-1px, 0, 0)";
      input.setAttribute("aria-valuetext", String(Math.round(value)) + "%");
    };
    const observer = typeof ResizeObserver === "undefined" ? null : new ResizeObserver(update);
    addCleanup(() => {
      if (observer) observer.disconnect();
      input.value = initial.value;
      after.style.clipPath = initial.clipPath;
      divider.style.insetInlineStart = initial.insetInlineStart;
      divider.style.transform = initial.transform;
      if (initial.valueText === null) input.removeAttribute("aria-valuetext");
      else input.setAttribute("aria-valuetext", initial.valueText);
    });
    on(input, "input", update);
    if (observer) observer.observe(comparison);
    update();
    return cleanup;
  };
  document.querySelectorAll("[data-motion=\"before-after-slider\"]").forEach((root) => {
    const cleanupKey = "__motionLexiconCleanup";
    if (typeof root[cleanupKey] === "function") root[cleanupKey]();
    root[cleanupKey] = mount(root, config);
  });
})();