/* ==========================================================================
   Kit — component styles. Reads tokens.css, writes no colour of its own.
   Every class is prefixed `k-` so it can be dropped into any project
   (Next, Astro, plain HTML) without colliding with existing styles.

   LAYER MODEL (this is the part that makes it look current, not the blur):
     content layer  → opaque surfaces: cards, fields, page background.
     floating layer → glass: nav bar, toolbars, tabs, menus, sheets, toasts.
                      It sits ABOVE content and lets it peek through.
     transient      → a switch or slider knob turns to glass WHILE dragged,
                      then goes back to solid.
   Do not put glass in the content layer, and never stack glass on glass.
   ========================================================================== */

[class^="k-"],
[class*=" k-"],
[class^="k-"]::before,
[class^="k-"]::after {
  box-sizing: border-box;
}

/* --------------------------------------------------------------------------
   1. The material itself — reusable on any floating surface.
   `.k-glass`         regular variant: blurs and lifts luminosity, legible
                      over anything. Default for bars, menus, sheets.
   `.k-glass--clear`  clear variant: for bars floating over photo/video only.
                      Pair it with `.k-dim` on the media underneath.
   `.k-glass--tinted` accent-tinted glass, for ONE prominent action.
   -------------------------------------------------------------------------- */
.k-glass {
  position: relative;
  background: var(--k-glass);
  backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  -webkit-backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  border: 1px solid var(--k-glass-line);
  box-shadow: var(--k-specular), var(--k-shadow-float);
  color: var(--k-text);
}

.k-glass--clear {
  background: var(--k-glass-clear);
  backdrop-filter: blur(calc(var(--k-blur) / 2)) saturate(var(--k-saturate));
  -webkit-backdrop-filter: blur(calc(var(--k-blur) / 2)) saturate(var(--k-saturate));
}

.k-glass--tinted {
  background: color-mix(in srgb, var(--k-accent) var(--k-glass-tint), var(--k-glass));
}

/* Dimming layer for bright media sitting under clear glass (HIG: 35%). */
.k-dim::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--k-glass-dim);
  pointer-events: none;
}

/* No backdrop-filter (old Firefox, GPU refused): fall back to a solid
   surface rather than an unreadable transparent one. */
@supports not ((backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px))) {
  .k-glass,
  .k-glass--clear {
    background: var(--k-surface);
  }
}

/* --------------------------------------------------------------------------
   2. Button
   Content layer:  --primary (filled) | --secondary | --ghost | --danger
   Floating layer: --glass | --glass-prominent (tinted, one per bar)
   Sizes: --sm | (default) | --lg
   Press feedback is a scale, not a colour jump: it reads as physical.
   -------------------------------------------------------------------------- */
.k-btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--k-sp-2);
  min-height: var(--k-control-h);
  padding: 0 var(--k-sp-5);
  border: 1px solid transparent;
  border-radius: var(--k-r-pill);
  background: var(--k-accent);
  color: var(--k-accent-ink);
  font-family: var(--k-font);
  font-size: var(--k-fs-md);
  font-weight: var(--k-fw-semibold);
  line-height: 1;
  letter-spacing: -0.01em;
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  transition: background var(--k-t-fast) var(--k-ease),
              border-color var(--k-t-fast) var(--k-ease),
              box-shadow var(--k-t-fast) var(--k-ease),
              transform var(--k-t-fast) var(--k-ease),
              opacity var(--k-t-fast) var(--k-ease);
}

.k-btn:hover { background: color-mix(in srgb, var(--k-accent) 88%, black); }
.k-btn:active { transform: scale(0.96); background: color-mix(in srgb, var(--k-accent) 78%, black); }
.k-btn:focus-visible { outline: var(--k-focus-ring); outline-offset: var(--k-focus-offset); }

.k-btn:disabled,
.k-btn[aria-disabled="true"] { opacity: 0.4; cursor: not-allowed; transform: none; }

.k-btn--secondary {
  background: var(--k-surface);
  color: var(--k-text);
  border-color: var(--k-line);
  box-shadow: var(--k-shadow-1);
}
.k-btn--secondary:hover { background: var(--k-surface-2); border-color: var(--k-line-strong); }
.k-btn--secondary:active { background: var(--k-surface-sunken); }

.k-btn--ghost { background: transparent; color: var(--k-accent); }
.k-btn--ghost:hover { background: color-mix(in srgb, var(--k-accent) 10%, transparent); }
.k-btn--ghost:active { background: color-mix(in srgb, var(--k-accent) 16%, transparent); }

.k-btn--danger { background: var(--k-danger); color: #fff; }
.k-btn--danger:hover { background: color-mix(in srgb, var(--k-danger) 88%, black); }
.k-btn--danger:active { background: color-mix(in srgb, var(--k-danger) 78%, black); }

/* Glass buttons — for the floating layer only. Label stays monochrome so it
   reads over whatever scrolls underneath. */
.k-btn--glass {
  background: var(--k-glass);
  backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  -webkit-backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  border-color: var(--k-glass-line);
  color: var(--k-text);
  box-shadow: var(--k-specular), var(--k-shadow-2);
}
.k-btn--glass:hover { background: color-mix(in srgb, var(--k-text) 8%, var(--k-glass)); }

.k-btn--glass-prominent {
  background: color-mix(in srgb, var(--k-accent) 82%, transparent);
  backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  -webkit-backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  border-color: color-mix(in srgb, white 30%, transparent);
  color: var(--k-accent-ink);
  box-shadow: var(--k-specular), var(--k-shadow-2);
}
.k-btn--glass-prominent:hover { background: color-mix(in srgb, var(--k-accent) 92%, transparent); }

.k-btn--sm { min-height: var(--k-control-h-sm); padding: 0 var(--k-sp-4); font-size: var(--k-fs-sm); }
.k-btn--lg { min-height: var(--k-control-h-lg); padding: 0 var(--k-sp-6); font-size: var(--k-fs-lg); }

/* Square icon-only button: same height, no horizontal padding drift. */
.k-btn--icon { padding: 0; width: var(--k-control-h); }
.k-btn--icon.k-btn--sm { width: var(--k-control-h-sm); }
.k-btn--icon.k-btn--lg { width: var(--k-control-h-lg); }

/* Loading: the label stays in place (no layout jump), a spinner replaces it. */
.k-btn[data-loading="true"] { pointer-events: none; }
.k-btn[data-loading="true"] .k-btn__label { opacity: 0; }
.k-btn[data-loading="true"]::after {
  content: "";
  position: absolute;
  width: 1em;
  height: 1em;
  border: 2px solid currentColor;
  border-right-color: transparent;
  border-radius: 50%;
  animation: k-spin 620ms linear infinite;
}

@keyframes k-spin { to { transform: rotate(360deg); } }

/* --------------------------------------------------------------------------
   3. Switch — a content-layer control that becomes glass DURING the gesture,
   which is exactly the exception the HIG carves out for transient controls.
   Click to flip, or drag the knob: it follows the finger, then snaps.
   -------------------------------------------------------------------------- */
.k-switch {
  --w: 64px;
  --h: 36px;
  --pad: 3px;
  --knob: calc(var(--h) - var(--pad) * 2);
  --travel: calc(var(--w) - var(--knob) - var(--pad) * 2);
  position: relative;
  flex: none;
  width: var(--w);
  height: var(--h);
  margin: 0;
  padding: 0;
  border: none;
  border-radius: var(--k-r-pill);
  background: var(--k-line-strong);
  cursor: pointer;
  touch-action: none;              /* the drag is handled in JS */
  -webkit-tap-highlight-color: transparent;
  transition: background var(--k-t-slow) var(--k-ease);
}

.k-switch[aria-checked="true"] { background: var(--k-success); }
.k-switch:disabled { opacity: 0.4; cursor: not-allowed; }
.k-switch:focus-visible { outline: var(--k-focus-ring); outline-offset: var(--k-focus-offset); }

.k-switch__knob {
  position: absolute;
  top: var(--pad);
  left: var(--pad);
  width: var(--knob);
  height: var(--knob);
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.18), 0 1px 1px rgba(0, 0, 0, 0.16);
  transform: translateX(var(--x, 0));
  will-change: transform;
  transition: transform var(--k-t-slow) var(--k-ease),
              width var(--k-t) var(--k-ease),
              background var(--k-t) var(--k-ease),
              box-shadow var(--k-t) var(--k-ease);
}

.k-switch[aria-checked="true"] .k-switch__knob { --x: var(--travel); }

.k-switch.is-dragging .k-switch__knob {
  background: rgba(255, 255, 255, 0.45);
  backdrop-filter: blur(10px) saturate(160%);
  -webkit-backdrop-filter: blur(10px) saturate(160%);
  box-shadow: var(--k-specular), 0 6px 18px rgba(0, 0, 0, 0.22);
  width: calc(var(--knob) + 6px);
  transition: none;                /* follow the finger with no lag */
}

/* --------------------------------------------------------------------------
   4. Slider — same transient-glass rule as the switch: the knob turns to
   glass and grows while dragged. Fill width is driven by --v (0 to 1).
   -------------------------------------------------------------------------- */
.k-slider {
  --track-h: 10px;
  --knob: 30px;
  position: relative;
  display: block;
  width: 100%;
  height: var(--knob);
  touch-action: none;
  cursor: pointer;
}

.k-slider__track {
  position: absolute;
  top: 50%;
  left: 0;
  right: 0;
  height: var(--track-h);
  margin-top: calc(var(--track-h) / -2);
  border-radius: var(--k-r-pill);
  background: var(--k-line);
  overflow: hidden;
}

.k-slider__fill {
  position: absolute;
  inset: 0;
  transform-origin: left center;
  transform: scaleX(var(--v, 0));
  background: var(--k-accent);
  transition: transform var(--k-t-fast) var(--k-ease);
}

.k-slider__knob {
  position: absolute;
  top: 50%;
  left: calc(var(--v, 0) * 100%);
  width: var(--knob);
  height: var(--knob);
  margin: calc(var(--knob) / -2) 0 0 calc(var(--knob) / -2);
  border-radius: 50%;
  background: var(--k-surface);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2), 0 1px 1px rgba(0, 0, 0, 0.12);
  transition: left var(--k-t-fast) var(--k-ease),
              width var(--k-t) var(--k-ease),
              height var(--k-t) var(--k-ease),
              background var(--k-t) var(--k-ease);
}

.k-slider.is-dragging .k-slider__knob {
  width: calc(var(--knob) + 8px);
  height: calc(var(--knob) + 8px);
  margin: calc((var(--knob) + 8px) / -2) 0 0 calc((var(--knob) + 8px) / -2);
  background: rgba(255, 255, 255, 0.45);
  backdrop-filter: blur(12px) saturate(170%);
  -webkit-backdrop-filter: blur(12px) saturate(170%);
  box-shadow: var(--k-specular), 0 6px 20px rgba(0, 0, 0, 0.24);
  transition: none;
}

.k-slider.is-dragging .k-slider__fill { transition: none; }
.k-slider:focus-visible { outline: none; }
.k-slider:focus-visible .k-slider__knob { box-shadow: var(--k-focus), 0 2px 8px rgba(0, 0, 0, 0.2); }

/* --------------------------------------------------------------------------
   5. Field: label + control + hint/error. Content layer: opaque.
   -------------------------------------------------------------------------- */
.k-field { display: flex; flex-direction: column; gap: var(--k-sp-2); }

.k-label {
  font-family: var(--k-font);
  font-size: var(--k-fs-sm);
  font-weight: var(--k-fw-semibold);
  color: var(--k-text);
  letter-spacing: -0.005em;
}

.k-label__optional { font-weight: var(--k-fw-regular); color: var(--k-text-3); }

.k-input,
.k-textarea,
.k-select {
  width: 100%;
  min-height: var(--k-control-h);
  padding: 0 var(--k-sp-4);
  border: 1px solid var(--k-line);
  border-radius: var(--k-r-md);
  background: var(--k-surface);
  color: var(--k-text);
  font-family: var(--k-font);
  font-size: var(--k-fs-md);
  line-height: var(--k-lh);
  transition: border-color var(--k-t-fast) var(--k-ease),
              box-shadow var(--k-t-fast) var(--k-ease),
              background var(--k-t-fast) var(--k-ease);
}

.k-textarea { padding: var(--k-sp-3) var(--k-sp-4); min-height: 104px; resize: vertical; }

.k-input::placeholder,
.k-textarea::placeholder { color: var(--k-text-3); }

.k-input:hover,
.k-textarea:hover,
.k-select:hover { border-color: var(--k-line-strong); }

.k-input:focus,
.k-textarea:focus,
.k-select:focus {
  outline: none;
  border-color: var(--k-accent);
  box-shadow: var(--k-focus);
}

.k-input:disabled,
.k-textarea:disabled,
.k-select:disabled {
  background: var(--k-surface-sunken);
  color: var(--k-text-3);
  cursor: not-allowed;
}

.k-input[aria-invalid="true"],
.k-textarea[aria-invalid="true"],
.k-select[aria-invalid="true"] { border-color: var(--k-danger); }

.k-input[aria-invalid="true"]:focus,
.k-textarea[aria-invalid="true"]:focus,
.k-select[aria-invalid="true"]:focus {
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--k-danger) 30%, transparent);
}

.k-hint { font-family: var(--k-font); font-size: var(--k-fs-sm); color: var(--k-text-2); }

.k-error {
  display: flex;
  align-items: flex-start;    /* the icon stays on the first line when the text wraps */
  gap: var(--k-sp-1);
  line-height: 1.35;
  font-family: var(--k-font);
  font-size: var(--k-fs-sm);
  color: var(--k-danger);
}

/* Select: native element, custom chevron (no JS, keeps mobile pickers). */
.k-select {
  appearance: none;
  padding-right: var(--k-sp-10);
  background-image: url("data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' width='14' height='9' viewBox='0 0 14 9' fill='none'%3E%3Cpath d='M1 1.5L7 7.5L13 1.5' stroke='%23888' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right var(--k-sp-4) center;
  cursor: pointer;
}

/* --------------------------------------------------------------------------
   6. Checkbox & radio — native input, custom box, real keyboard support.
   -------------------------------------------------------------------------- */
.k-check {
  display: inline-flex;
  align-items: flex-start;
  gap: var(--k-sp-3);
  font-family: var(--k-font);
  font-size: var(--k-fs-md);
  color: var(--k-text);
  cursor: pointer;
  user-select: none;
}

.k-check input {
  appearance: none;
  flex: none;
  width: 22px;
  height: 22px;
  margin: 0;
  border: 1.5px solid var(--k-line-strong);
  border-radius: var(--k-r-xs);
  background: var(--k-surface);
  cursor: pointer;
  transition: background var(--k-t-fast) var(--k-ease),
              border-color var(--k-t-fast) var(--k-ease),
              box-shadow var(--k-t-fast) var(--k-ease);
}

.k-check input[type="radio"] { border-radius: 50%; }

.k-check input:checked {
  background: var(--k-accent) no-repeat center;
  border-color: var(--k-accent);
  background-image: url("data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' width='14' height='11' viewBox='0 0 14 11' fill='none'%3E%3Cpath d='M1.5 5.5L5 9L12.5 1.5' stroke='white' stroke-width='2.2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
}

.k-check input[type="radio"]:checked {
  background-image: none;
  box-shadow: inset 0 0 0 5px var(--k-surface);
}

.k-check input:focus-visible { outline: var(--k-focus-ring); outline-offset: var(--k-focus-offset); }
.k-check input:disabled { opacity: 0.4; cursor: not-allowed; }

/* --------------------------------------------------------------------------
   7. Card — content layer, opaque. Media nested inside uses a CONCENTRIC
   radius: inner = outer - padding, so curves stay parallel.
   -------------------------------------------------------------------------- */
.k-card {
  --pad: var(--k-sp-5);
  display: flex;
  flex-direction: column;
  border: 1px solid var(--k-line);
  border-radius: var(--k-r-lg);
  background: var(--k-surface);
  box-shadow: var(--k-shadow-1);
  overflow: hidden;
  transition: transform var(--k-t) var(--k-ease),
              box-shadow var(--k-t) var(--k-ease),
              border-color var(--k-t) var(--k-ease);
}

.k-card__body { padding: var(--pad); display: flex; flex-direction: column; gap: var(--k-sp-2); }
.k-card__header { padding: var(--pad) var(--pad) 0; }

.k-card__media {
  margin: var(--pad) var(--pad) 0;
  border-radius: calc(var(--k-r-lg) - var(--pad) / 2);   /* concentric with the card */
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background: var(--k-surface-sunken);
}

.k-card__media img { display: block; width: 100%; height: 100%; object-fit: cover; }

.k-card__footer {
  padding: var(--k-sp-4) var(--pad);
  border-top: 1px solid var(--k-line);
  background: var(--k-surface-2);
  display: flex;
  gap: var(--k-sp-2);
  justify-content: flex-end;
}

.k-card__title {
  margin: 0;
  font-family: var(--k-font);
  font-size: var(--k-fs-lg);
  font-weight: var(--k-fw-semibold);
  letter-spacing: var(--k-track-tight);
  color: var(--k-text);
}

.k-card__text { margin: 0; font-family: var(--k-font); font-size: var(--k-fs-md); line-height: var(--k-lh); color: var(--k-text-2); }

.k-card--interactive { cursor: pointer; }
.k-card--interactive:hover { transform: translateY(-2px); box-shadow: var(--k-shadow-2); border-color: var(--k-line-strong); }
.k-card--interactive:active { transform: translateY(0); }
.k-card--interactive:focus-visible { outline: var(--k-focus-ring); outline-offset: var(--k-focus-offset); }

/* --------------------------------------------------------------------------
   8. Nav — floating glass bar. It does not span the full width edge to edge:
   it is inset and rounded, so content is visible around and under it.
   -------------------------------------------------------------------------- */
.k-nav {
  position: sticky;
  top: var(--k-sp-3);
  z-index: 40;
  display: flex;
  align-items: center;
  gap: var(--k-sp-4);
  height: var(--k-bar-h);
  margin: 0 auto;
  padding: 0 var(--k-sp-3) 0 var(--k-sp-5);
  width: min(1100px, calc(100% - var(--k-sp-8)));
  border-radius: var(--k-r-pill);
  background: var(--k-glass);
  backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  -webkit-backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  border: 1px solid var(--k-glass-line);
  box-shadow: var(--k-specular), var(--k-shadow-float);
}

.k-nav__brand {
  font-family: var(--k-font);
  font-size: var(--k-fs-lg);
  font-weight: var(--k-fw-semibold);
  letter-spacing: var(--k-track-tight);
  color: var(--k-text);
  text-decoration: none;
}

.k-nav__links { display: flex; align-items: center; gap: var(--k-sp-1); margin-left: auto; }

.k-nav__link {
  padding: var(--k-sp-2) var(--k-sp-4);
  /* concentric with the pill bar */
  border-radius: var(--k-r-pill);
  color: var(--k-text-2);
  font-family: var(--k-font);
  font-size: var(--k-fs-md);
  font-weight: var(--k-fw-medium);
  text-decoration: none;
  transition: background var(--k-t-fast) var(--k-ease), color var(--k-t-fast) var(--k-ease);
}

.k-nav__link:hover { background: color-mix(in srgb, var(--k-text) 8%, transparent); color: var(--k-text); }
.k-nav__link[aria-current="page"] { color: var(--k-text); background: color-mix(in srgb, var(--k-text) 10%, transparent); }
.k-nav__link:focus-visible { outline: var(--k-focus-ring); outline-offset: var(--k-focus-offset); }

/* Scroll edge effect: content that scrolls under the bar is progressively
   blurred and faded, so labels stay legible without a hard opaque band. */
.k-scroll-edge {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: calc(var(--k-bar-h) + var(--k-sp-8));
  z-index: 30;
  pointer-events: none;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  mask-image: linear-gradient(to bottom, #000 35%, transparent 100%);
  -webkit-mask-image: linear-gradient(to bottom, #000 35%, transparent 100%);
}

/* --------------------------------------------------------------------------
   9. Toolbar — the floating action bar. Items are GROUPED: related actions
   share one glass background, groups are separated by a gap (never a
   divider). Inner radius is concentric with the bar.
   -------------------------------------------------------------------------- */
.k-toolbar {
  position: fixed;
  left: 50%;
  bottom: var(--k-sp-6);
  z-index: 45;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: var(--k-sp-3);
}

.k-toolbar__group {
  display: flex;
  align-items: center;
  gap: 2px;
  padding: var(--k-bar-pad);
  border-radius: var(--k-r-2xl);
  background: var(--k-glass);
  backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  -webkit-backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  border: 1px solid var(--k-glass-line);
  box-shadow: var(--k-specular), var(--k-shadow-float);
}

.k-toolbar__item {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--k-sp-2);
  min-width: 44px;
  height: 44px;
  padding: 0 var(--k-sp-4);
  border: 0;
  /* concentric: bar radius minus its own padding */
  border-radius: calc(var(--k-r-2xl) - var(--k-bar-pad));
  background: transparent;
  color: var(--k-text);
  font-family: var(--k-font);
  font-size: var(--k-fs-md);
  font-weight: var(--k-fw-medium);
  cursor: pointer;
  transition: background var(--k-t-fast) var(--k-ease), transform var(--k-t-fast) var(--k-ease);
}

.k-toolbar__item:hover { background: color-mix(in srgb, var(--k-text) 10%, transparent); }
.k-toolbar__item:active { transform: scale(0.94); }
.k-toolbar__item:focus-visible { outline: var(--k-focus-ring); outline-offset: var(--k-focus-offset); }
.k-toolbar__item[aria-pressed="true"] { background: color-mix(in srgb, var(--k-accent) 18%, transparent); color: var(--k-accent); }

/* One prominent action per bar: tinted glass, per the HIG's colour guidance. */
.k-toolbar__item--prominent {
  background: color-mix(in srgb, var(--k-accent) 88%, transparent);
  color: var(--k-accent-ink);
}
.k-toolbar__item--prominent:hover { background: var(--k-accent); }

/* --------------------------------------------------------------------------
   10. Tabs — floating segmented control in glass; the selected pill is a
   brighter piece of glass that slides. --i = active index, --n = count.
   -------------------------------------------------------------------------- */
.k-tabs {
  position: relative;
  display: inline-flex;
  padding: var(--k-bar-pad);
  border-radius: var(--k-r-pill);
  background: var(--k-glass);
  backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  -webkit-backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  border: 1px solid var(--k-glass-line);
  box-shadow: var(--k-specular), var(--k-shadow-2);
  isolation: isolate;
}

.k-tabs__slider {
  position: absolute;
  z-index: -1;
  top: var(--k-bar-pad);
  bottom: var(--k-bar-pad);
  left: var(--k-bar-pad);
  width: calc((100% - var(--k-bar-pad) * 2) / var(--n, 1));
  border-radius: var(--k-r-pill);
  background: var(--k-surface);
  box-shadow: var(--k-specular), var(--k-shadow-1);
  transform: translateX(calc(100% * var(--i, 0)));
  transition: transform var(--k-t) var(--k-ease);
}

.k-tab {
  flex: 1;
  min-height: 38px;
  padding: 0 var(--k-sp-5);
  border: 0;
  border-radius: var(--k-r-pill);
  background: transparent;
  color: var(--k-text-2);
  font-family: var(--k-font);
  font-size: var(--k-fs-md);
  font-weight: var(--k-fw-medium);
  white-space: nowrap;
  cursor: pointer;
  transition: color var(--k-t-fast) var(--k-ease);
}

.k-tab[aria-selected="true"] { color: var(--k-text); }
.k-tab:hover:not([aria-selected="true"]) { color: var(--k-text); }
.k-tab:focus-visible { outline: var(--k-focus-ring); outline-offset: var(--k-focus-offset); }

/* --------------------------------------------------------------------------
   11. Tooltip — CSS only, shows on hover AND keyboard focus.
   -------------------------------------------------------------------------- */
.k-tip { position: relative; display: inline-flex; }

.k-tip__bubble {
  position: absolute;
  bottom: calc(100% + var(--k-sp-2));
  left: 50%;
  z-index: 50;
  padding: var(--k-sp-2) var(--k-sp-3);
  border-radius: var(--k-r-sm);
  background: color-mix(in srgb, var(--k-text) 92%, transparent);
  color: var(--k-bg);
  font-family: var(--k-font);
  font-size: var(--k-fs-sm);
  line-height: 1.35;
  white-space: nowrap;
  opacity: 0;
  transform: translate(-50%, 4px);
  pointer-events: none;
  transition: opacity var(--k-t-fast) var(--k-ease), transform var(--k-t-fast) var(--k-ease);
}

.k-tip:hover .k-tip__bubble,
.k-tip:focus-within .k-tip__bubble { opacity: 1; transform: translate(-50%, 0); }

/* --------------------------------------------------------------------------
   12. Menu — glass panel, morphs out of its trigger. [data-open] toggled in JS.
   -------------------------------------------------------------------------- */
.k-menu { position: relative; display: inline-flex; }

.k-menu__list {
  --pad: var(--k-sp-2);
  position: absolute;
  top: calc(100% + var(--k-sp-2));
  left: 0;
  z-index: 50;
  min-width: 220px;
  margin: 0;
  padding: var(--pad);
  list-style: none;
  border-radius: var(--k-r-lg);
  background: var(--k-glass);
  backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  -webkit-backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  border: 1px solid var(--k-glass-line);
  box-shadow: var(--k-specular), var(--k-shadow-3);
  opacity: 0;
  transform: translateY(-6px) scale(0.96);
  transform-origin: top left;
  visibility: hidden;
  transition: opacity var(--k-t-fast) var(--k-ease),
              transform var(--k-t) var(--k-ease-spring),
              visibility var(--k-t-fast);
}

.k-menu[data-open="true"] .k-menu__list { opacity: 1; transform: none; visibility: visible; }
.k-menu--right .k-menu__list { left: auto; right: 0; transform-origin: top right; }

.k-menu__item {
  display: flex;
  align-items: center;
  gap: var(--k-sp-3);
  width: 100%;
  min-height: 40px;
  padding: var(--k-sp-2) var(--k-sp-3);
  border: 0;
  border-radius: calc(var(--k-r-lg) - var(--pad));   /* concentric with the panel */
  background: transparent;
  color: var(--k-text);
  font-family: var(--k-font);
  font-size: var(--k-fs-md);
  text-align: left;
  text-decoration: none;
  cursor: pointer;
  transition: background var(--k-t-fast) var(--k-ease);
}

/* Icons in menu items: the HIG asks for them on common actions. */
.k-menu__item span[aria-hidden] { width: 20px; text-align: center; opacity: 0.75; }
.k-menu__item:hover { background: color-mix(in srgb, var(--k-text) 10%, transparent); }
.k-menu__item:focus-visible { outline: var(--k-focus-ring); outline-offset: var(--k-focus-offset); }
.k-menu__item--danger { color: var(--k-danger); }
.k-menu__sep { height: 1px; margin: var(--k-sp-2) var(--k-sp-3); background: var(--k-line); border: 0; }

/* --------------------------------------------------------------------------
   13. Modal / sheet — glass, larger radius, inset from the edges so the
   content underneath peeks through.
   -------------------------------------------------------------------------- */
.k-modal {
  width: min(540px, calc(100vw - var(--k-sp-8)));
  padding: 0;
  border: 1px solid var(--k-glass-line);
  border-radius: var(--k-r-2xl);
  background: var(--k-glass);
  backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  -webkit-backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  color: var(--k-text);
  box-shadow: var(--k-specular), var(--k-shadow-3);
  overflow: hidden;
}

.k-modal::backdrop {
  background: rgba(16, 17, 26, 0.28);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

.k-modal[open] { animation: k-modal-in var(--k-t-slow) var(--k-ease-spring); }
.k-modal[open]::backdrop { animation: k-fade-in var(--k-t) var(--k-ease); }

@keyframes k-modal-in {
  from { opacity: 0; transform: translateY(16px) scale(0.94); }
  to   { opacity: 1; transform: none; }
}
@keyframes k-fade-in { from { opacity: 0; } to { opacity: 1; } }

.k-modal__header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--k-sp-4);
  padding: var(--k-sp-6) var(--k-sp-6) 0;
}

.k-modal__title {
  margin: 0;
  font-family: var(--k-font);
  font-size: var(--k-fs-xl);
  font-weight: var(--k-fw-semibold);
  letter-spacing: var(--k-track-tight);
}

.k-modal__body {
  padding: var(--k-sp-3) var(--k-sp-6) var(--k-sp-6);
  font-family: var(--k-font);
  font-size: var(--k-fs-md);
  line-height: var(--k-lh);
  color: var(--k-text-2);
}

.k-modal__footer {
  display: flex;
  justify-content: flex-end;
  gap: var(--k-sp-2);
  padding: var(--k-sp-4) var(--k-sp-6);
  border-top: 1px solid var(--k-glass-line);
}

/* --------------------------------------------------------------------------
   14. Toast — floating glass, stacked bottom-right.
   -------------------------------------------------------------------------- */
.k-toasts {
  position: fixed;
  z-index: 60;
  right: var(--k-sp-5);
  bottom: var(--k-sp-5);
  display: flex;
  flex-direction: column-reverse;
  gap: var(--k-sp-2);
  pointer-events: none;
}

.k-toast {
  display: flex;
  align-items: center;
  gap: var(--k-sp-3);
  min-width: 280px;
  max-width: min(400px, calc(100vw - var(--k-sp-10)));
  padding: var(--k-sp-3) var(--k-sp-4);
  border: 1px solid var(--k-glass-line);
  border-radius: var(--k-r-lg);
  background: var(--k-glass);
  backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  -webkit-backdrop-filter: blur(var(--k-blur)) saturate(var(--k-saturate)) brightness(var(--k-glass-brightness));
  box-shadow: var(--k-specular), var(--k-shadow-float);
  color: var(--k-text);
  font-family: var(--k-font);
  font-size: var(--k-fs-md);
  pointer-events: auto;
  animation: k-toast-in var(--k-t-slow) var(--k-ease-spring);
}

.k-toast.is-leaving { animation: k-toast-out var(--k-t) var(--k-ease) forwards; }

.k-toast__dot { flex: none; width: 8px; height: 8px; border-radius: 50%; background: var(--k-accent); }
.k-toast--success .k-toast__dot { background: var(--k-success); }
.k-toast--danger .k-toast__dot { background: var(--k-danger); }
.k-toast--warning .k-toast__dot { background: var(--k-warning); }
.k-toast__text { flex: 1; }
.k-toast__close {
  flex: none; border: 0; background: transparent; color: var(--k-text-3);
  font-size: var(--k-fs-lg); line-height: 1; cursor: pointer; padding: var(--k-sp-1);
  border-radius: var(--k-r-xs);
}
.k-toast__close:hover { color: var(--k-text); background: color-mix(in srgb, var(--k-text) 10%, transparent); }
.k-toast__close:focus-visible { outline: var(--k-focus-ring); outline-offset: var(--k-focus-offset); }

@keyframes k-toast-in { from { opacity: 0; transform: translateY(12px) scale(0.96); } to { opacity: 1; transform: none; } }
@keyframes k-toast-out { to { opacity: 0; transform: translateY(6px) scale(0.98); } }

/* --------------------------------------------------------------------------
   15. Badge
   -------------------------------------------------------------------------- */
.k-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--k-sp-1);
  padding: 4px var(--k-sp-3);
  border-radius: var(--k-r-pill);
  background: color-mix(in srgb, var(--k-text) 8%, transparent);
  color: var(--k-text-2);
  font-family: var(--k-font);
  font-size: var(--k-fs-xs);
  font-weight: var(--k-fw-semibold);
  letter-spacing: 0.01em;
  white-space: nowrap;
}

.k-badge--accent  { background: color-mix(in srgb, var(--k-accent) 14%, transparent);  color: var(--k-accent-text); }
.k-badge--success { background: color-mix(in srgb, var(--k-success) 16%, transparent); color: #17692f; }
.k-badge--warning { background: color-mix(in srgb, var(--k-warning) 18%, transparent); color: color-mix(in srgb, var(--k-warning) 45%, black); }
.k-badge--danger  { background: color-mix(in srgb, var(--k-danger) 14%, transparent);  color: #c8100a; }

/* --------------------------------------------------------------------------
   16. Skeleton — loading placeholder. Sized by the caller.
   -------------------------------------------------------------------------- */
.k-skeleton {
  position: relative;
  overflow: hidden;
  border-radius: var(--k-r-sm);
  background: var(--k-surface-sunken);
}

.k-skeleton::after {
  content: "";
  position: absolute;
  inset: 0;
  transform: translateX(-100%);
  background: linear-gradient(90deg, transparent, color-mix(in srgb, var(--k-surface) 70%, transparent), transparent);
  animation: k-shimmer 1.4s var(--k-ease-inout) infinite;
}

@keyframes k-shimmer { to { transform: translateX(100%); } }

.k-skeleton--text { height: 0.9em; border-radius: var(--k-r-xs); }
.k-skeleton--circle { border-radius: 50%; }

/* --------------------------------------------------------------------------
   17. Empty state — icon, one sentence, one action. Never a bare "no data".
   -------------------------------------------------------------------------- */
.k-empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--k-sp-3);
  padding: var(--k-sp-12) var(--k-sp-6);
  text-align: center;
  font-family: var(--k-font);
}

.k-empty__icon {
  display: grid;
  place-items: center;
  width: 60px;
  height: 60px;
  border-radius: var(--k-r-xl);
  background: var(--k-surface-sunken);
  color: var(--k-text-3);
  font-size: var(--k-fs-2xl);
}

.k-empty__title { margin: 0; font-size: var(--k-fs-lg); font-weight: var(--k-fw-semibold); color: var(--k-text); letter-spacing: var(--k-track-tight); }
.k-empty__text { margin: 0; max-width: 42ch; font-size: var(--k-fs-md); line-height: var(--k-lh); color: var(--k-text-2); }

/* --------------------------------------------------------------------------
   18. Motion preference — one global opt-out, never overridden per component.
   -------------------------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  [class^="k-"],
  [class*=" k-"],
  [class^="k-"]::after,
  [class^="k-"]::before {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}