Bootstrap 5 Fill-on-Hover Buttons

<section class="wdw-stage">
  <div class="container" style="max-width:860px">
    <div class="wdw-card p-4 p-md-5">
      <div class="d-flex flex-column flex-sm-row align-items-sm-start gap-3 gap-md-4 mb-4">
        <span class="wdw-icon flex-shrink-0" style="width:3.5rem;height:3.5rem" aria-hidden="true">
          <svg viewBox="0 0 24 24" width="28" height="28" fill="none" stroke="currentColor" stroke-width="1.75" stroke-linecap="round" stroke-linejoin="round"><path d="M12 3a9 9 0 1 0 9 9 4 4 0 0 1-4-4 4 4 0 0 1-4-4 1 1 0 0 0-1-1Z"/><circle cx="8.5" cy="11" r=".6" fill="currentColor"/><circle cx="12" cy="16" r=".6" fill="currentColor"/><circle cx="15.5" cy="13" r=".6" fill="currentColor"/></svg>
        </span>
        <div>
          <span class="wdw-eyebrow mb-1">Cookie preferences</span>
          <h2 class="wdw-heading h2 mb-2">Help us make this site better</h2>
          <p class="wdw-muted mb-0">We use cookies to keep you signed in and to understand which pages are useful. You can change your choice at any time.</p>
        </div>
      </div>
      <div class="d-flex flex-column flex-sm-row align-items-sm-center gap-3">
        <button type="button" class="btn fill-btn fill-btn-primary fill-left rounded-pill px-4" data-demo><span>Accept all</span></button>
        <button type="button" class="btn fill-btn fill-btn-secondary fill-center rounded-pill px-4"><span>Refuse</span></button>
        <button type="button" class="btn fill-link fill-up px-2"><span>More info</span></button>
      </div>
      <hr class="my-4">
      <a href="#" class="link-primary fw-semibold small text-decoration-none">Manage preferences</a>
    </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 */
.fill-btn, .fill-link {
  --fill: var(--bs-primary);
  --fill-text: #fff;
  position: relative;
  overflow: hidden;
  isolation: isolate;
  color: var(--fill);
  background: transparent;
  border: 2px solid var(--fill);
  transition: color .35s ease, box-shadow .35s ease, transform .2s ease;
}
.fill-btn::before, .fill-link::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: var(--fill);
  transition: transform .4s cubic-bezier(.2, .7, .2, 1);
}
.fill-left::before { transform: scaleX(0); transform-origin: left; }
.fill-center::before { transform: scale(0); border-radius: 50%; inset: -25% 0; }
.fill-up::before { transform: scaleY(0); transform-origin: bottom; }
.fill-btn:hover, .fill-btn:focus-visible, .fill-btn:active, .fill-btn[data-demo],
.fill-link:hover, .fill-link:focus-visible, .fill-link:active { color: var(--fill-text); }
.fill-btn:hover, .fill-btn:focus-visible, .fill-btn:active, .fill-btn[data-demo] { box-shadow: 0 10px 24px -10px var(--fill); }
.fill-left:hover::before, .fill-left:focus-visible::before, .fill-left:active::before, .fill-left[data-demo]::before { transform: scaleX(1); }
.fill-center:hover::before, .fill-center:focus-visible::before, .fill-center:active::before { transform: scale(1.6); }
.fill-up:hover::before, .fill-up:focus-visible::before, .fill-up:active::before { transform: scaleY(1); }
.fill-btn:focus-visible, .fill-link:focus-visible { outline: 3px solid var(--bs-focus-ring-color); outline-offset: 3px; }
.fill-btn-secondary { --fill: var(--bs-secondary-color); --fill-text: var(--bs-body-bg); border-color: var(--bs-border-color); }
.fill-link { border-color: transparent; font-weight: 600; border-radius: .5rem; min-height: 44px; }
[data-bs-theme="dark"] .fill-btn-primary { --fill-text: #0f1117; }
@media (prefers-reduced-motion: reduce) { .fill-btn, .fill-link, .fill-btn::before, .fill-link::before { transition: none; } }

;