Bootstrap 5 3D Carousel with Autoplay and Spread Options

<section class="wdw-stage">
  <div class="container" style="max-width:1000px">
    <div class="text-center mb-4">
      <span class="wdw-eyebrow">Gallery</span>
      <h2 class="wdw-heading display-6 mt-1 mb-2">3D Carousel</h2>
      <p class="wdw-muted mb-0">Click a photo, use the arrows, or press the arrow keys.</p>
    </div>
    <div class="wdw-card p-3 p-md-4">
      <div class="c3d" id="c3d" tabindex="0" role="region" aria-roledescription="carousel" aria-label="Photo carousel"><button type="button" class="c3d-slide" aria-label="Spring blossoms"><img src="https://images.unsplash.com/photo-1490750967868-88aa4486c946?auto=format&fit=crop&w=720&h=480&q=70" alt="Spring blossoms" width="720" height="480" draggable="false"></button><button type="button" class="c3d-slide" aria-label="Sunlit valley"><img src="https://images.unsplash.com/photo-1469474968028-56623f02e42e?auto=format&fit=crop&w=720&h=480&q=70" alt="Sunlit valley" width="720" height="480" draggable="false"></button><button type="button" class="c3d-slide" aria-label="Forest light"><img src="https://images.unsplash.com/photo-1441974231531-c6227db76b6e?auto=format&fit=crop&w=720&h=480&q=70" alt="Forest light" width="720" height="480" draggable="false"></button><button type="button" class="c3d-slide" aria-label="Mountain meadow"><img src="https://images.unsplash.com/photo-1506744038136-46273834b3fb?auto=format&fit=crop&w=720&h=480&q=70" alt="Mountain meadow" width="720" height="480" draggable="false"></button><button type="button" class="c3d-slide" aria-label="Alpine lake"><img src="https://images.unsplash.com/photo-1501785888041-af3ef285b470?auto=format&fit=crop&w=720&h=480&q=70" alt="Alpine lake" width="720" height="480" draggable="false"></button><button type="button" class="c3d-slide" aria-label="Misty hills"><img src="https://images.unsplash.com/photo-1470071459604-3b5ec3a7fe05?auto=format&fit=crop&w=720&h=480&q=70" alt="Misty hills" width="720" height="480" draggable="false"></button><button type="button" class="c3d-slide" aria-label="Green fields"><img src="https://images.unsplash.com/photo-1472214103451-9374bd1c798e?auto=format&fit=crop&w=720&h=480&q=70" alt="Green fields" width="720" height="480" draggable="false"></button></div>
      <p class="text-center fw-semibold mb-3" id="c3dCaption" aria-live="polite"></p>
      <div class="d-flex flex-wrap align-items-center justify-content-center gap-3">
        <button type="button" class="btn btn-outline-primary rounded-pill" id="c3dPrev" aria-label="Previous photo">← Prev</button>
        <button type="button" class="btn btn-primary rounded-pill" id="c3dNext" aria-label="Next photo">Next →</button>
        <div class="form-check form-switch ms-md-3 mb-0">
          <input class="form-check-input" type="checkbox" role="switch" id="c3dAuto">
          <label class="form-check-label" for="c3dAuto">Autoplay</label>
        </div>
        <div class="d-flex align-items-center gap-2">
          <label for="c3dSpread" class="small wdw-muted mb-0">Spread</label>
          <input type="range" class="form-range" id="c3dSpread" min="40" max="140" value="90" style="width:120px">
        </div>
      </div>
    </div>
  </div>
</section>

/* Web Designer Wall library style — shared base for every Bootstrap 5 snippet.
   Indigo accent, Plus Jakarta Sans, soft cards, pill buttons. Works in light and dark. */
@import url("https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800&display=swap");

:root,
[data-bs-theme="light"] {
  --wdw-font: "Plus Jakarta Sans", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --bs-body-font-family: var(--wdw-font);
  --bs-primary: #4f46e5;
  --bs-primary-rgb: 79, 70, 229;
  --bs-primary-text-emphasis: #3730a3;
  --bs-primary-bg-subtle: #eef2ff;
  --bs-primary-border-subtle: #c7d2fe;
  --bs-link-color: #4f46e5;
  --bs-link-color-rgb: 79, 70, 229;
  --bs-link-hover-color: #4338ca;
  --bs-link-hover-color-rgb: 67, 56, 202;
  --bs-focus-ring-color: rgba(79, 70, 229, 0.25);
  --bs-border-radius: 0.75rem;
  --bs-border-radius-lg: 1rem;
  --bs-border-radius-xl: 1.25rem;
  --wdw-radius-card: 1.25rem;
  --wdw-shadow: 0 1px 2px rgba(16, 24, 40, 0.05), 0 16px 40px -16px rgba(16, 24, 40, 0.22);
  --wdw-shadow-sm: 0 1px 2px rgba(16, 24, 40, 0.06), 0 4px 12px -4px rgba(16, 24, 40, 0.12);
  --wdw-stage: #f5f6fb;
}

[data-bs-theme="dark"] {
  --bs-primary: #818cf8;
  --bs-primary-rgb: 129, 140, 248;
  --bs-primary-text-emphasis: #c7d2fe;
  --bs-primary-bg-subtle: rgba(129, 140, 248, 0.14);
  --bs-primary-border-subtle: rgba(129, 140, 248, 0.35);
  --bs-link-color: #a5b4fc;
  --bs-link-color-rgb: 165, 180, 252;
  --bs-link-hover-color: #c7d2fe;
  --bs-link-hover-color-rgb: 199, 210, 254;
  --bs-focus-ring-color: rgba(129, 140, 248, 0.35);
  --wdw-shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 16px 40px -16px rgba(0, 0, 0, 0.7);
  --wdw-shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4), 0 4px 12px -4px rgba(0, 0, 0, 0.5);
  --wdw-stage: #0f1117;
}

body { font-family: var(--wdw-font); -webkit-font-smoothing: antialiased; }

/* Bootstrap compiles its blue into these components; point them at the accent. */
.btn-primary {
  --bs-btn-bg: var(--bs-primary); --bs-btn-border-color: var(--bs-primary);
  --bs-btn-hover-bg: #4338ca; --bs-btn-hover-border-color: #4338ca;
  --bs-btn-active-bg: #3730a3; --bs-btn-active-border-color: #3730a3;
  --bs-btn-disabled-bg: var(--bs-primary); --bs-btn-disabled-border-color: var(--bs-primary);
  --bs-btn-focus-shadow-rgb: var(--bs-primary-rgb);
}
[data-bs-theme="dark"] .btn-primary { --bs-btn-color: #0f1117; --bs-btn-hover-bg: #a5b4fc; --bs-btn-hover-border-color: #a5b4fc; --bs-btn-hover-color: #0f1117; --bs-btn-active-color: #0f1117; }
.btn-outline-primary {
  --bs-btn-color: var(--bs-primary); --bs-btn-border-color: var(--bs-primary);
  --bs-btn-hover-bg: var(--bs-primary); --bs-btn-hover-border-color: var(--bs-primary);
  --bs-btn-active-bg: var(--bs-primary); --bs-btn-active-border-color: var(--bs-primary);
  --bs-btn-focus-shadow-rgb: var(--bs-primary-rgb);
}
.btn { --bs-btn-font-weight: 600; min-height: 44px; display: inline-flex; align-items: center; justify-content: center; gap: .5rem; }
.btn-sm { min-height: 36px; }
.form-control, .form-select { min-height: 44px; border-radius: .75rem; }
.form-control:focus, .form-select:focus, .form-check-input:focus { border-color: rgba(var(--bs-primary-rgb), .6); box-shadow: 0 0 0 .25rem var(--bs-focus-ring-color); }
.form-check-input:checked { background-color: var(--bs-primary); border-color: var(--bs-primary); }
.nav-pills { --bs-nav-pills-link-active-bg: var(--bs-primary); }
.nav { --bs-nav-link-color: var(--bs-secondary-color); --bs-nav-link-hover-color: var(--bs-emphasis-color); }
.pagination { --bs-pagination-active-bg: var(--bs-primary); --bs-pagination-active-border-color: var(--bs-primary); --bs-pagination-color: var(--bs-body-color); --bs-pagination-focus-box-shadow: 0 0 0 .25rem var(--bs-focus-ring-color); }
.progress, .progress-stacked { --bs-progress-bar-bg: var(--bs-primary); }
.list-group { --bs-list-group-active-bg: var(--bs-primary); --bs-list-group-active-border-color: var(--bs-primary); }
.dropdown-menu { --bs-dropdown-link-active-bg: var(--bs-primary); border-radius: .875rem; box-shadow: var(--wdw-shadow-sm); }
.accordion { --bs-accordion-active-bg: var(--bs-primary-bg-subtle); --bs-accordion-active-color: var(--bs-primary-text-emphasis); --bs-accordion-btn-focus-box-shadow: 0 0 0 .25rem var(--bs-focus-ring-color); }
.badge { font-weight: 600; }

/* Library building blocks — use these instead of re-inventing them per snippet. */
.wdw-stage { min-height: 100vh; display: flex; align-items: center; background: var(--wdw-stage); padding-block: 3rem; }
.wdw-card { background: var(--bs-body-bg); border: 1px solid var(--bs-border-color-translucent); border-radius: var(--wdw-radius-card); box-shadow: var(--wdw-shadow); }
.wdw-card-sm { background: var(--bs-body-bg); border: 1px solid var(--bs-border-color-translucent); border-radius: 1rem; box-shadow: var(--wdw-shadow-sm); }
.wdw-aurora { position: relative; color: #fff; background: radial-gradient(60% 55% at 100% 0, #818cf8 0, transparent 70%), radial-gradient(65% 60% at 0 100%, #ec4899 0, transparent 65%), #1e1b4b; }
.wdw-eyebrow { display: inline-block; font-size: .75rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--bs-primary); }
.wdw-heading { font-weight: 800; letter-spacing: -.02em; color: var(--bs-emphasis-color); }
.wdw-muted { color: var(--bs-secondary-color); }
.wdw-icon { width: 2.75rem; height: 2.75rem; flex: none; display: inline-flex; align-items: center; justify-content: center; border-radius: .875rem; background: var(--bs-primary-bg-subtle); color: var(--bs-primary); }

/* Component */
.c3d{position:relative;height:300px;perspective:1100px;overflow:hidden;outline:0;margin-bottom:1rem;border-radius:1rem}
.c3d:focus-visible{box-shadow:0 0 0 .25rem var(--bs-focus-ring-color)}
.c3d-slide{position:absolute;top:50%;left:50%;width:min(300px,56%);aspect-ratio:3/2;padding:0;border:4px solid var(--bs-body-bg);border-radius:1rem;overflow:hidden;background:var(--bs-tertiary-bg);box-shadow:0 18px 40px -14px rgba(16,24,40,.45);cursor:pointer;transition:transform .55s cubic-bezier(.2,.8,.2,1),opacity .55s,filter .55s;will-change:transform}
.c3d-slide img{width:100%;height:100%;object-fit:cover;display:block;pointer-events:none}
.c3d-slide:focus-visible{outline:3px solid var(--bs-primary);outline-offset:2px}
@media (max-width:575px){.c3d{height:220px}}
@media (prefers-reduced-motion:reduce){.c3d-slide{transition:none}}
.form-range{accent-color:var(--bs-primary)}.form-range::-webkit-slider-thumb{background:var(--bs-primary)}.form-range::-moz-range-thumb{background:var(--bs-primary)}

(function initCarousel3d() {
  var root = document.getElementById('c3d');
  if (!root) return;
  var slides = Array.prototype.slice.call(root.querySelectorAll('.c3d-slide'));
  var caption = document.getElementById('c3dCaption');
  var spread = document.getElementById('c3dSpread');
  var auto = document.getElementById('c3dAuto');
  var cur = Math.floor(slides.length / 2), timer = null;
  function render() {
    var gap = +spread.value, n = slides.length;
    slides.forEach(function (s, i) {
      var d = i - cur;
      var abs = Math.abs(d);
      var shown = abs <= 3;
      s.style.transform = 'translate(-50%,-50%) translateX(' + d * gap + 'px) translateZ(' + (-abs * 90) + 'px) rotateY(' + (-Math.sign(d) * Math.min(abs, 2) * 28) + 'deg)';
      s.style.zIndex = n - abs;
      s.style.opacity = shown ? 1 - abs * 0.18 : 0;
      s.style.filter = abs ? 'brightness(' + (1 - abs * 0.12) + ')' : 'none';
      s.style.pointerEvents = shown ? 'auto' : 'none';
      s.tabIndex = d === 0 ? 0 : -1;
      s.setAttribute('aria-current', d === 0 ? 'true' : 'false');
    });
    caption.textContent = slides[cur].getAttribute('aria-label') + ' (' + (cur + 1) + ' of ' + n + ')';
  }
  function go(i) { cur = (i + slides.length) % slides.length; render(); }
  function stop() { clearInterval(timer); timer = null; }
  slides.forEach(function (s, i) { s.addEventListener('click', function () { go(i); }); });
  document.getElementById('c3dPrev').addEventListener('click', function () { go(cur - 1); });
  document.getElementById('c3dNext').addEventListener('click', function () { go(cur + 1); });
  root.addEventListener('keydown', function (e) {
    if (e.key === 'ArrowLeft') { e.preventDefault(); go(cur - 1); }
    if (e.key === 'ArrowRight') { e.preventDefault(); go(cur + 1); }
  });
  spread.addEventListener('input', render);
  auto.addEventListener('change', function () {
    stop();
    if (auto.checked) timer = setInterval(function () { go(cur + 1); }, 2500);
  });
  render();
})();