Bootstrap 5 Horizontal Expanding Accordion

<section class="wdw-stage"><div class="container" style="max-width:1000px">
<div class="text-center mb-4"><span class="wdw-eyebrow">What we do</span><h2 class="wdw-heading display-6 mt-1">From first sketch to launch day</h2></div>
<div class="wdw-hacc wdw-card-sm p-2 gap-2">
<div class="wdw-hpanel is-open"><button type="button" class="wdw-hbtn" aria-expanded="true" aria-controls="hp0" id="hb0"><span class="wdw-icon"><i class="bi bi-palette" aria-hidden="true"></i></span><span class="wdw-hlabel">Design</span><span class="wdw-hnum" aria-hidden="true">01</span></button><div class="wdw-hbody" id="hp0" role="region" aria-labelledby="hb0"><div class="wdw-hinner d-flex flex-column h-100"><h3 class="h4 fw-bold mb-2 d-flex align-items-center wdw-htitle">Design</h3><p class="wdw-muted mb-3">Systems, brand identity and interfaces that feel consistent across every screen and touchpoint.</p><div class="mt-auto d-flex align-items-end justify-content-between gap-3"><div><div class="fs-2 fw-bold text-primary lh-1">120+</div><div class="small wdw-muted mt-1">design systems shipped</div></div><a href="#" class="link-primary fw-semibold text-decoration-none">Learn more <i class="bi bi-arrow-right" aria-hidden="true"></i></a></div></div></div></div>
<div class="wdw-hpanel"><button type="button" class="wdw-hbtn" aria-expanded="false" aria-controls="hp1" id="hb1"><span class="wdw-icon"><i class="bi bi-code-slash" aria-hidden="true"></i></span><span class="wdw-hlabel">Develop</span><span class="wdw-hnum" aria-hidden="true">02</span></button><div class="wdw-hbody" id="hp1" role="region" aria-labelledby="hb1"><div class="wdw-hinner d-flex flex-column h-100"><h3 class="h4 fw-bold mb-2 d-flex align-items-center wdw-htitle">Develop</h3><p class="wdw-muted mb-3">Clean, accessible front-end builds that are fast on real devices and easy to maintain.</p><div class="mt-auto d-flex align-items-end justify-content-between gap-3"><div><div class="fs-2 fw-bold text-primary lh-1">98</div><div class="small wdw-muted mt-1">average Lighthouse score</div></div><a href="#" class="link-primary fw-semibold text-decoration-none">Learn more <i class="bi bi-arrow-right" aria-hidden="true"></i></a></div></div></div></div>
<div class="wdw-hpanel"><button type="button" class="wdw-hbtn" aria-expanded="false" aria-controls="hp2" id="hb2"><span class="wdw-icon"><i class="bi bi-graph-up-arrow" aria-hidden="true"></i></span><span class="wdw-hlabel">Grow</span><span class="wdw-hnum" aria-hidden="true">03</span></button><div class="wdw-hbody" id="hp2" role="region" aria-labelledby="hb2"><div class="wdw-hinner d-flex flex-column h-100"><h3 class="h4 fw-bold mb-2 d-flex align-items-center wdw-htitle">Grow</h3><p class="wdw-muted mb-3">Analytics, experiments and SEO work that turn steady traffic into measurable results.</p><div class="mt-auto d-flex align-items-end justify-content-between gap-3"><div><div class="fs-2 fw-bold text-primary lh-1">3.4x</div><div class="small wdw-muted mt-1">average organic growth</div></div><a href="#" class="link-primary fw-semibold text-decoration-none">Learn more <i class="bi bi-arrow-right" aria-hidden="true"></i></a></div></div></div></div>
<div class="wdw-hpanel"><button type="button" class="wdw-hbtn" aria-expanded="false" aria-controls="hp3" id="hb3"><span class="wdw-icon"><i class="bi bi-headset" aria-hidden="true"></i></span><span class="wdw-hlabel">Support</span><span class="wdw-hnum" aria-hidden="true">04</span></button><div class="wdw-hbody" id="hp3" role="region" aria-labelledby="hb3"><div class="wdw-hinner d-flex flex-column h-100"><h3 class="h4 fw-bold mb-2 d-flex align-items-center wdw-htitle">Support</h3><p class="wdw-muted mb-3">Friendly help when you need it, with documented fixes and quick turnarounds.</p><div class="mt-auto d-flex align-items-end justify-content-between gap-3"><div><div class="fs-2 fw-bold text-primary lh-1"><4h</div><div class="small wdw-muted mt-1">first response time</div></div><a href="#" class="link-primary fw-semibold text-decoration-none">Learn more <i class="bi bi-arrow-right" aria-hidden="true"></i></a></div></div></div></div>
<div class="wdw-hpanel"><button type="button" class="wdw-hbtn" aria-expanded="false" aria-controls="hp4" id="hb4"><span class="wdw-icon"><i class="bi bi-rocket-takeoff" aria-hidden="true"></i></span><span class="wdw-hlabel">Launch</span><span class="wdw-hnum" aria-hidden="true">05</span></button><div class="wdw-hbody" id="hp4" role="region" aria-labelledby="hb4"><div class="wdw-hinner d-flex flex-column h-100"><h3 class="h4 fw-bold mb-2 d-flex align-items-center wdw-htitle">Launch</h3><p class="wdw-muted mb-3">Staging, QA and a calm release day, followed by monitoring and polish.</p><div class="mt-auto d-flex align-items-end justify-content-between gap-3"><div><div class="fs-2 fw-bold text-primary lh-1">0</div><div class="small wdw-muted mt-1">minutes of downtime</div></div><a href="#" class="link-primary fw-semibold text-decoration-none">Learn more <i class="bi bi-arrow-right" aria-hidden="true"></i></a></div></div></div></div>
</div></div></section>

@import url("https://cdnjs.cloudflare.com/ajax/libs/bootstrap-icons/1.11.3/font/bootstrap-icons.min.css");
/* 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 */
.wdw-hacc{display:flex;flex-direction:column}
.wdw-hpanel{display:grid;grid-template-rows:auto 0fr;border-radius:.875rem;background:var(--bs-tertiary-bg);overflow:hidden;transition:grid-template-rows .4s cubic-bezier(.4,0,.2,1),background .3s}
.wdw-hpanel.is-open{grid-template-rows:auto 1fr;background:var(--bs-primary-bg-subtle)}
.wdw-hbtn{position:relative;display:flex;align-items:center;gap:.75rem;min-height:64px;padding:.6rem .75rem;border:0;background:transparent;color:var(--bs-body-color);font:inherit;text-align:start;cursor:pointer}
.wdw-hbtn:focus-visible{outline:0;box-shadow:inset 0 0 0 .2rem var(--bs-focus-ring-color);border-radius:.875rem}
.wdw-hlabel{font-weight:700}
.wdw-hnum{margin-inline-start:auto;font-size:.75rem;font-weight:700;color:var(--bs-secondary-color)}
.wdw-hbody{min-height:0;overflow:hidden;visibility:hidden;opacity:0;transition:opacity .25s,visibility 0s .4s}
.wdw-hpanel.is-open .wdw-hbody{visibility:visible;opacity:1;transition:opacity .25s .2s,visibility 0s}
.wdw-hinner{padding:.25rem 1rem 1rem}
.wdw-hpanel.is-open .wdw-icon{background:var(--bs-primary);color:#fff}
[data-bs-theme="dark"] .wdw-hpanel.is-open .wdw-icon{color:#0f1117}
@media (min-width:768px){
  .wdw-hacc{flex-direction:row;height:380px}
  .wdw-hpanel{display:flex;flex:1 1 0;min-width:0;transition:flex-grow .5s cubic-bezier(.4,0,.2,1),background .3s}
  .wdw-hpanel.is-open{flex-grow:6}
  .wdw-hbtn{flex:1 0 4.5rem;flex-direction:column;justify-content:space-between;padding:1.1rem .5rem}
  .wdw-hpanel.is-open .wdw-hbtn{flex:0 0 4.5rem}
  .wdw-hlabel{writing-mode:vertical-rl;transform:rotate(180deg);letter-spacing:.04em}
  .wdw-hpanel.is-open .wdw-hlabel{position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap}
  .wdw-hnum{margin:0}
  .wdw-hbody{flex:0 0 0;min-width:0;transition:opacity .25s,visibility 0s .5s}
  .wdw-hpanel.is-open .wdw-hbody{flex:1 1 0;transition:opacity .25s .25s,visibility 0s}
  .wdw-hinner{width:min(28rem,100%);min-width:19rem;padding:1.1rem 1.5rem 1.1rem 0}
  .wdw-htitle{min-height:2.75rem}
}
@media (prefers-reduced-motion:reduce){.wdw-hpanel,.wdw-hbody{transition:none!important}}

function initHorizontalAccordion() {
  const panels = document.querySelectorAll('.wdw-hpanel');
  if (!panels.length) return;
  const open = (panel) => {
    panels.forEach((p) => {
      const on = p === panel;
      p.classList.toggle('is-open', on);
      p.querySelector('.wdw-hbtn').setAttribute('aria-expanded', on);
    });
  };
  panels.forEach((panel) => {
    const btn = panel.querySelector('.wdw-hbtn');
    btn.addEventListener('click', () => open(panel));
    btn.addEventListener('keydown', (e) => {
      const list = [...panels];
      const i = list.indexOf(panel);
      const next = e.key === 'ArrowRight' || e.key === 'ArrowDown' ? list[i + 1] : e.key === 'ArrowLeft' || e.key === 'ArrowUp' ? list[i - 1] : null;
      if (next) { e.preventDefault(); next.querySelector('.wdw-hbtn').focus(); open(next); }
    });
  });
}
initHorizontalAccordion();