Niveus/niveus/components/timepicker.css

/* ==========================================================================
   Niveus — Time picker
   --------------------------------------------------------------------------
     <div class="nv-timepicker nv-surface" data-nv-timepicker
          data-nv-value="09:30" data-nv-step="5" data-nv-format-toggle></div>

   Wheels, as on a phone: each column scrolls and snaps, and whatever sits in
   the lens across the middle is the value. Scrolling, snapping, momentum and
   touch are the browser's; niveus.js builds the columns, reads which row is
   centred, and exposes the value as data-nv-value and an `nv:time` event.

   The lens is the selection colour laid over the centre row, so it follows the
   brand. Rows fade towards the top and bottom with a mask rather than a
   coloured gradient, which keeps the fade right on any surface — solid, or
   Glaze with something moving behind it.

   The format is 24-hour unless told otherwise. With data-nv-format-toggle a
   third wheel reads 24H / AM / PM: swipe it to AM or PM and the hour wheel
   becomes 1–12; swipe back to 24H and it returns to 0–23. The value stays
   24-hour either way, so a form never has to know which the person used.

   Without niveus.js the element is empty. For a no-script fallback, use a
   native <input type="time" class="nv-input">.
   ========================================================================== */

.nv-timepicker {
  --_row: 2.25rem;
  --_rows: 5;

  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: var(--nv-space-2);
  padding: var(--nv-space-2) var(--nv-space-3);
  border-radius: var(--nv-radius-xl);
  color: var(--nv-color-text-primary);
}

.nv-timepicker__wheels {
  position: relative;
  display: flex;
  gap: var(--nv-space-1);
}

/* The lens: a bar of tinted glass lying across the centre row. It is raised
   like the keys elsewhere in the system — lit on top, shaded below, with a
   contact line — not a flat band of colour, so it reads as a thing the wheels
   pass under. */
.nv-timepicker__wheels::before {
  content: "";
  position: absolute;
  inset-inline: calc(var(--nv-space-2) * -1);
  inset-block-start: 50%;
  block-size: var(--_row);
  translate: 0 -50%;
  background-color: var(--nv-color-selection);
  background-image: var(--nv-sheen-raised);
  border-radius: var(--nv-radius-md);
  box-shadow: var(--nv-bevel), var(--nv-outline), var(--nv-elevation-1);
  pointer-events: none;
}

.nv-timepicker__column {
  position: relative;
  inline-size: 3.5rem;
  block-size: calc(var(--_row) * var(--_rows));
  margin: 0;
  padding: 0;
  list-style: none;
  cursor: grab;
  user-select: none;
  touch-action: pan-y;
  overflow-y: auto;
  overscroll-behavior: contain;
  scroll-snap-type: y mandatory;
  scrollbar-width: none;
  mask-image: linear-gradient(
    transparent,
    currentcolor 28%,
    currentcolor 72%,
    transparent
  );
  /* Depth for the drum effect below: rows turn away from the viewer as they
     leave the centre. */
  perspective: 14rem;
}

.nv-timepicker__column::-webkit-scrollbar {
  display: none;
}

/* Spacers, not padding: they let the first and last rows reach the centre.
   Firefox leaves the bottom padding of a scroll container out of its
   scrollable area, which stranded the last rows (and made a three-row wheel
   unscrollable); real boxes always count. */
.nv-timepicker__column::before,
.nv-timepicker__column::after {
  content: "";
  display: block;
  block-size: calc(var(--_row) * (var(--_rows) - 1) / 2);
}

.nv-timepicker__column[data-nv-dragging] {
  cursor: grabbing;
}

.nv-timepicker__column:focus-visible {
  outline: none;
  border-radius: var(--nv-radius-md);
  box-shadow: var(--nv-focus-ring);
}

.nv-timepicker__option {
  display: grid;
  place-items: center;
  block-size: var(--_row);
  scroll-snap-align: center;
  color: var(--nv-color-text-tertiary);
  font: var(--nv-font-label);
  font-size: var(--nv-font-size-lg);
  font-variant-numeric: tabular-nums;
  cursor: pointer;
  /* --nv-pull is how far the wheel has been dragged past its end. Letting go
     removes it, and the spring easing carries the rows back with a small
     overshoot — the way a phone's list gives at its limit and settles. */
  translate: 0 var(--nv-pull, 0);
  transition:
    var(--nv-transition-colors),
    translate var(--nv-duration-slower) var(--nv-ease-spring);
}

.nv-timepicker__column[data-nv-pulling] .nv-timepicker__option {
  transition: var(--nv-transition-colors);
}

/* A drum: each row shrinks, fades and tilts away in proportion to how far it
   is from the lens. Driven by the scroll position itself, so it needs no
   script and tracks a finger exactly. Where scroll-driven animation is missing
   the rows are simply flat, which is still correct. */
@supports (animation-timeline: view()) {
  @media (prefers-reduced-motion: no-preference) {
    .nv-timepicker__option {
      animation: nv-wheel-drum linear both;
      animation-timeline: view(block);
    }
  }
}

@keyframes nv-wheel-drum {
  0% { scale: 0.78; opacity: 0.25; rotate: x 52deg; }
  50% { scale: 1; opacity: 1; rotate: x 0deg; }
  100% { scale: 0.78; opacity: 0.25; rotate: x -52deg; }
}

.nv-timepicker__option[aria-selected="true"] {
  color: var(--nv-color-text-primary);
  font-weight: var(--nv-font-weight-semibold);
}

.nv-timepicker__separator {
  display: grid;
  place-items: center;
  align-self: center;
  color: var(--nv-color-text-tertiary);
  font: var(--nv-font-label);
  font-size: var(--nv-font-size-lg);
}