/*
 * Greig McRitchie — a full-screen photo slideshow.
 *
 * Two render paths share one markup:
 *   html.no-js  a plain stacked gallery (no JavaScript, or a browser too old for import maps)
 *   html.js     the full-screen slideshow driven by app/javascript/slideshow.js
 */

:root {
  --ink: 255 255 255;
  --stage: 0 0 0;
  --fade: 900ms;
  --chrome-fade: 400ms;
  --font: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --ui-font: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  color-scheme: dark;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  background: rgb(var(--stage));
  color: rgb(var(--ink));
  font-family: var(--ui-font);
  -webkit-font-smoothing: antialiased;
}

img {
  display: block;
  max-width: 100%;
  height: auto;
}

/* Read by screen readers, never seen: the live region that names each photo. */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

/* ---------- no-js: a quiet stacked gallery ---------- */

html.no-js .slideshow {
  max-width: 64rem;
  margin: 0 auto;
  padding: 2rem 1rem 4rem;
}

html.no-js .slideshow__title {
  font-family: var(--font);
  font-weight: 400;
  font-size: clamp(1.75rem, 5vw, 3rem);
  text-align: center;
  margin: 0 0 2rem;
}

html.no-js .slide {
  margin: 0 0 2rem;
}

html.no-js .slide__backdrop,
html.no-js .slideshow__controls,
html.no-js .slideshow__hint {
  display: none;
}

html.no-js .slide__photo {
  margin: 0 auto;
  max-height: 90vh;
  width: auto;
}

/* ---------- js: the full-screen slideshow ---------- */

html.js,
html.js body {
  height: 100%;
  overflow: hidden;
  overscroll-behavior: none;
}

html.js .slideshow {
  position: fixed;
  inset: 0;
  height: 100vh;
  height: 100dvh;
  overflow: hidden;
  background: rgb(var(--stage));
  user-select: none;
  -webkit-user-select: none;
  -webkit-tap-highlight-color: transparent;
}

html.js .slideshow__stage {
  position: absolute;
  inset: 0;
  touch-action: pan-y pinch-zoom;
}

html.js .slide {
  position: absolute;
  inset: 0;
  margin: 0;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--fade) ease, visibility 0s linear var(--fade);
}

html.js .slide.is-active {
  opacity: 1;
  visibility: visible;
  transition: opacity var(--fade) ease, visibility 0s linear 0s;
}

/* The same photo, blown up and blurred, fills the letterbox so a portrait
   photo on a landscape screen (or the reverse) never sits in dead black. */
html.js .slide__backdrop {
  position: absolute;
  inset: -8%;
  width: 116%;
  height: 116%;
  max-width: none;
  object-fit: cover;
  filter: blur(40px) saturate(1.1) brightness(0.45);
  transform: translateZ(0);
}

html.js .slide__photo {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
  padding: max(env(safe-area-inset-top), 0.5rem) max(env(safe-area-inset-right), 0.5rem)
    max(env(safe-area-inset-bottom), 0.5rem) max(env(safe-area-inset-left), 0.5rem);
  filter: drop-shadow(0 1.5rem 3rem rgb(0 0 0 / 0.55));
}

/* A slow drift while a photo is on screen (skipped under reduced motion).
   A transition, not an animation: when a slide leaves, the delay holds its
   drifted scale through the fade-out and resets it only once it is hidden. */
html.js .slide__photo {
  transform: scale(1);
  transition: transform 0s linear var(--fade);
}

html.js .slide.is-active .slide__photo {
  transform: scale(1.04);
  transition: transform 12s ease-out;
}

/* ---------- chrome: title, controls, hint ---------- */

html.js .slideshow__title {
  position: absolute;
  z-index: 2;
  top: max(env(safe-area-inset-top), 1.25rem);
  left: max(env(safe-area-inset-left), 1.5rem);
  margin: 0;
  font-family: var(--font);
  font-weight: 400;
  font-size: clamp(1.1rem, 2.6vw, 1.75rem);
  letter-spacing: 0.02em;
  text-shadow: 0 1px 12px rgb(0 0 0 / 0.7);
  pointer-events: none;
}

.slideshow__controls {
  position: absolute;
  z-index: 2;
  left: 50%;
  bottom: max(env(safe-area-inset-bottom), 1.25rem);
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.35rem;
  border-radius: 999px;
  background: rgb(0 0 0 / 0.45);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 0 0 1px rgb(var(--ink) / 0.12);
}

.control {
  display: grid;
  place-items: center;
  width: 2.75rem;
  height: 2.75rem;
  padding: 0;
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: rgb(var(--ink));
  cursor: pointer;
  transition: background-color 150ms ease;
}

.control[hidden] {
  display: none;
}

.control:hover {
  background: rgb(var(--ink) / 0.14);
}

.control:focus-visible {
  outline: 2px solid rgb(var(--ink));
  outline-offset: 2px;
}

.control svg {
  width: 1.4rem;
  height: 1.4rem;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.control svg .fill {
  fill: currentColor;
  stroke: none;
}

.control[aria-pressed="true"] .icon-play,
.control[aria-pressed="false"] .icon-pause,
.control[aria-pressed="true"] .icon-expand,
.control[aria-pressed="false"] .icon-collapse {
  display: none;
}

.slideshow__counter {
  min-width: 4.5ch;
  padding: 0 0.35rem;
  font-size: 0.9rem;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
  text-align: center;
  color: rgb(var(--ink) / 0.85);
}

html.js .slideshow__hint {
  position: absolute;
  z-index: 2;
  left: 0;
  right: 0;
  bottom: calc(max(env(safe-area-inset-bottom), 1.25rem) + 4.25rem);
  margin: 0;
  text-align: center;
  font-size: 0.85rem;
  color: rgb(var(--ink) / 0.7);
  text-shadow: 0 1px 8px rgb(0 0 0 / 0.8);
  pointer-events: none;
  transition: opacity 1.2s ease;
}

html.js .slideshow__hint.is-gone {
  opacity: 0;
}

/* The chrome fades away while nobody is touching anything, and comes back
   on any movement, tap, or keyboard focus. */
html.js .slideshow__title,
.slideshow__controls {
  transition: opacity var(--chrome-fade) ease;
}

html.js .slideshow.is-idle .slideshow__title,
html.js .slideshow.is-idle .slideshow__controls {
  opacity: 0;
}

/* Hidden controls take no taps: a finger on the invisible bar lands on the
   stage, which wakes the chrome instead of pressing a button unseen. A click
   or tap leaves focus on the button, so this must not key off :focus-within;
   keyboard focus never meets is-idle, because the script wakes on focusin and
   will not sleep while a control is :focus-visible. */
html.js .slideshow.is-idle .slideshow__controls {
  pointer-events: none;
}

html.js .slideshow.is-idle {
  cursor: none;
}

/* Belt and braces: a keyboard-focused control is never hidden. */
html.js .slideshow.is-idle .slideshow__controls:has(:focus-visible) {
  opacity: 1;
  pointer-events: auto;
}

/* ---------- reduced motion: cut, don't fade or drift ---------- */

@media (prefers-reduced-motion: reduce) {
  :root {
    --fade: 0ms;
    --chrome-fade: 0ms;
  }

  html.js .slide__photo,
  html.js .slide.is-active .slide__photo {
    transform: none;
    transition: none;
  }

  html.js .slideshow__hint {
    transition: none;
  }
}