/* Motion mechanics for the Iron guide. The look comes from tokens in styles.css:
   --bg --surface --ink --ink-2 --ink-3 --line --accent --on-accent --ease */

:root { --ease: cubic-bezier(.2,.8,.2,1); --dur: .42s; }
html { scrollbar-gutter: stable; }
html.lb-open { overflow: hidden; }
* { -webkit-tap-highlight-color: transparent; }
h3, h4, .acc-title, .cer-name b, .paths b { text-wrap: balance; }
.q, .d, li, .fix span, .tally, .lede, .note, .cer-name span { text-wrap: pretty; }

/* ---------- theme change ---------- */
html.vt-theme::view-transition-old(root),
html.vt-theme::view-transition-new(root) { animation: none; mix-blend-mode: normal; }
html.vt-theme::view-transition-old(root) { z-index: 1; }
html.vt-theme::view-transition-new(root) { z-index: 2; }
html.vt-swap::view-transition-old(root),
html.vt-swap::view-transition-new(root) { animation-duration: .26s; animation-timing-function: ease; }
html.theme-fade, html.theme-fade * {
  transition: background-color .4s ease, color .4s ease, border-color .4s ease, fill .4s ease, stroke .4s ease !important;
}

/* ---------- theme toggle (sun / moon morph) ---------- */
.theme-toggle {
  position: relative; width: 2.5rem; height: 2.5rem; border-radius: 999px;
  display: inline-grid; place-items: center; cursor: pointer;
  background: transparent; color: var(--ink); border: 1px solid var(--line);
  transition: background-color .2s ease, border-color .2s ease, transform .15s ease;
}
.theme-toggle:hover { background: var(--surface); }
.theme-toggle:active { transform: scale(.94); }
.theme-toggle svg { width: 1.15rem; height: 1.15rem; overflow: visible; }
.theme-toggle .sun-core { transition: r .45s var(--ease); }
.theme-toggle .rays { transform-origin: 12px 12px; transition: transform .5s var(--ease), opacity .3s ease; }
.theme-toggle .moon-mask { transition: transform .5s var(--ease); }
.theme-toggle[aria-pressed="true"] .sun-core { r: 9px; }
.theme-toggle[aria-pressed="true"] .rays { transform: rotate(-60deg) scale(.4); opacity: 0; }
.theme-toggle[aria-pressed="true"] .moon-mask { transform: translate(-7px, 5px); }

/* ---------- accordion: height via grid rows, fully interruptible ---------- */
.acc-head { cursor: pointer; }
.acc-head .chev { transition: transform var(--dur) var(--ease); }
.acc-head[aria-expanded="true"] .chev { transform: rotate(180deg); }
.acc-panel {
  display: grid; grid-template-rows: 0fr; visibility: hidden;
  transition: grid-template-rows var(--dur) var(--ease), visibility 0s linear var(--dur);
}
.acc-panel > .acc-inner { min-height: 0; overflow: hidden; }
.acc-panel > .acc-inner > * { opacity: 0; transition: opacity .25s ease; }
.acc-head[aria-expanded="true"] + .acc-panel {
  grid-template-rows: 1fr; visibility: visible;
  transition: grid-template-rows var(--dur) var(--ease), visibility 0s linear 0s;
}
.acc-head[aria-expanded="true"] + .acc-panel > .acc-inner > * { opacity: 1; transition-delay: .08s; }

/* ---------- checklist ---------- */
.tick { display: grid; grid-template-columns: auto minmax(0, 1fr); column-gap: .85rem; cursor: pointer; position: relative; }
.tick input { position: absolute; opacity: 0; width: 1px; height: 1px; pointer-events: none; }
.tick .box {
  grid-row: 1; width: 1.4rem; height: 1.4rem; margin-top: .05rem; display: grid; place-items: center;
  border: 1.5px solid var(--ink-3); border-radius: var(--box-r, 6px); background: transparent;
  transition: background-color .22s ease, border-color .22s ease, transform .18s var(--ease);
}
.tick .box svg { width: 70%; height: 70%; fill: none; stroke: var(--on-accent); stroke-width: 2.6; stroke-linecap: round; stroke-linejoin: round; }
.tick .box path { stroke-dasharray: 22; stroke-dashoffset: 22; transition: stroke-dashoffset .3s var(--ease) .05s; }
.tick input:checked + .box { background: var(--accent); border-color: var(--accent); }
.tick input:checked + .box path { stroke-dashoffset: 0; }
.tick:active .box { transform: scale(.9); }
.tick input:focus-visible + .box { outline: 2px solid var(--accent); outline-offset: 3px; }
.tick .fix { grid-column: 2; display: grid; grid-template-rows: 0fr; transition: grid-template-rows var(--dur) var(--ease); }
.tick .fix > span { min-height: 0; overflow: hidden; opacity: 0; transition: opacity .25s ease; }
.tick input:checked ~ .fix { grid-template-rows: 1fr; }
.tick input:checked ~ .fix > span { opacity: 1; transition-delay: .1s; }

/* ---------- segmented switch ---------- */
.seg { position: relative; display: inline-flex; isolation: isolate; }
.seg button { position: relative; z-index: 1; cursor: pointer; font: inherit; background: transparent; border: 0; transition: color .25s ease; }
.seg-thumb {
  position: absolute; z-index: 0; top: var(--thumb-inset, 3px); bottom: var(--thumb-inset, 3px); left: 0;
  width: var(--w, 0); transform: translateX(var(--x, 0));
}
html.segs-ready .seg-thumb { transition: transform .42s var(--ease), width .42s var(--ease); }

/* ---------- product image button ---------- */
.zoomable { display: block; padding: 0; border: 0; background: none; cursor: zoom-in; position: relative; border-radius: var(--img-r, 8px); }
.zoomable img { display: block; width: 100%; height: auto; border-radius: inherit; transition: transform .3s var(--ease), box-shadow .3s ease; }
@media (hover: hover) { .zoomable:hover img { transform: translateY(-2px) scale(1.03); } }
.zoomable:active img { transform: scale(.97); }
.zoomable:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }

/* ---------- lightbox ---------- */
dialog.lb {
  position: fixed; inset: 0; width: 100%; height: 100%; max-width: none; max-height: none;
  margin: 0; padding: 0; border: 0; background: transparent; overflow: hidden; color: #fff;
}
dialog.lb::backdrop { background: transparent; }
.lb-scrim { position: absolute; inset: 0; background: rgba(12, 10, 9, .9); -webkit-backdrop-filter: blur(6px); backdrop-filter: blur(6px); }
.lb-stage { position: absolute; inset: 0; display: grid; place-items: center; touch-action: none; cursor: zoom-in; }
dialog.lb.is-zoomed .lb-stage { cursor: grab; }
.lb-zoom { will-change: transform; transform-origin: 50% 50%; }
.lb-card { background: #fff; border-radius: 14px; padding: clamp(14px, 3vw, 28px); box-shadow: 0 30px 80px rgba(0,0,0,.45); }
.lb-card img { display: block; max-height: min(74vh, 900px); max-width: min(82vw, 640px); width: auto; height: auto; user-select: none; -webkit-user-drag: none; pointer-events: none; }
.lb-bar { position: absolute; top: max(12px, env(safe-area-inset-top)); right: 12px; display: flex; gap: 8px; }
.lb-btn {
  width: 44px; height: 44px; border-radius: 999px; border: 0; cursor: pointer; display: grid; place-items: center;
  background: rgba(255,255,255,.14); color: #fff; transition: background-color .2s ease, transform .15s ease;
}
.lb-btn:hover { background: rgba(255,255,255,.24); }
.lb-btn:active { transform: scale(.92); }
.lb-btn svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; }
.lb-cap, .lb-hint { position: absolute; left: 0; right: 0; text-align: center; margin: 0; padding: 0 16px; pointer-events: none; transition: opacity .25s ease; }
.lb-cap { bottom: calc(max(16px, env(safe-area-inset-bottom)) + 22px); font-weight: 600; font-size: 1rem; }
.lb-hint { bottom: max(16px, env(safe-area-inset-bottom)); font-size: .8125rem; opacity: .65; }
dialog.lb.is-zoomed .lb-cap, dialog.lb.is-zoomed .lb-hint { opacity: 0; }

@media (prefers-reduced-motion: reduce) {
  :root { --dur: .01s; }
  html { scroll-behavior: auto !important; }
  .seg-thumb, html.segs-ready .seg-thumb, .zoomable img, .tick .box path { transition: none !important; }
}
@media print {
  .acc-panel { grid-template-rows: 1fr !important; visibility: visible !important; }
  .acc-panel > .acc-inner > * { opacity: 1 !important; transform: none !important; }
  .theme-toggle, .seg, .lb { display: none !important; }
}