:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --surface-2: #eef0f4;
  --border: #d9dde5;
  --text: #1a1d23;
  --muted: #5f6672;
  --accent: #2563eb;
  --accent-text: #ffffff;
  --a: #2563eb;
  --a-soft: #dbe6fd;
  --b: #d97706;
  --b-soft: #fdecd3;
  --c: #059669;
  --c-soft: #d4f3e6;
  --d: #c026d3;
  --d-soft: #f8dcfa;
  --e: #dc2626;
  --e-soft: #fde0e0;
  --f: #0891b2;
  --f-soft: #d3f1f7;
  --warn-bg: #fff6e0;
  --warn-text: #7a4b00;
  --error: #c2261b;
  --radius: 12px;
  --shadow: 0 1px 2px rgb(0 0 0 / 0.06), 0 2px 8px rgb(0 0 0 / 0.04);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111317;
    --surface: #1a1d23;
    --surface-2: #242830;
    --border: #333844;
    --text: #e7e9ee;
    --muted: #9aa1ad;
    --accent: #5b8cff;
    --accent-text: #0b0d12;
    --a: #6d9bff;
    --a-soft: #1d2b4d;
    --b: #f2a540;
    --b-soft: #3d2a10;
    --c: #34d399;
    --c-soft: #10362a;
    --d: #e879f9;
    --d-soft: #3e1942;
    --e: #f87171;
    --e-soft: #431b1b;
    --f: #22d3ee;
    --f-soft: #0f3540;
    --warn-bg: #3a2c0c;
    --warn-text: #f7d48a;
    --error: #ff7a6e;
    --shadow: none;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  -webkit-text-size-adjust: 100%;
}

button, input, select { font: inherit; color: inherit; }

.sr-only {
  position: absolute; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0 0 0 0); white-space: nowrap;
}

/* ---------- layout ---------- */

.top, main, .actions { max-width: 960px; margin-inline: auto; padding-inline: 16px; }

.top {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  column-gap: 10px;
  padding-block: 20px 4px;
}
.home {
  display: inline-flex; align-items: center; gap: 10px;
  color: inherit; text-decoration: none;
  font-size: 1.4rem; font-weight: 700; letter-spacing: -0.01em;
}
a.home:hover span { text-decoration: underline; }
.top h1 { margin: 0; font-size: 1.15rem; font-weight: 600; color: var(--muted); min-width: 0; }
.top h1::before { content: "▸ "; }
.language select {
  min-height: 36px; padding: 4px 8px;
  background: var(--surface);
  border: 1px solid var(--border); border-radius: 8px;
  font-size: 0.9rem; cursor: pointer;
}
.tagline { grid-column: 1 / -1; margin: 4px 0 0; color: var(--muted); font-size: 0.95rem; }

main { padding-bottom: 24px; }

.step { margin-top: 24px; }
.step h2 {
  display: flex; align-items: center; gap: 8px;
  margin: 0 0 10px; font-size: 1.05rem;
}
.num {
  display: inline-grid; place-items: center;
  width: 24px; height: 24px; border-radius: 50%;
  background: var(--text); color: var(--bg);
  font-size: 0.8rem; font-weight: 700;
}
.count { color: var(--muted); font-weight: 400; font-size: 0.9rem; }

/* ---------- file slots ---------- */

.slots {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 10px;
  align-items: stretch;
}

.slot {
  position: relative;
  min-height: 132px;
  background: var(--surface);
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  transition: border-color 0.15s, background 0.15s;
}
.slot.filled { border-style: solid; }
.slot[data-slot="0"].filled { border-color: var(--a); }
.slot[data-slot="1"].filled { border-color: var(--b); }
.slot.dragover { border-color: var(--accent); background: var(--surface-2); }

.slot-pick {
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 4px; height: 100%; min-height: 128px; padding: 16px;
  text-align: center; cursor: pointer; border-radius: var(--radius);
}
.slot-pick:focus-within { outline: 2px solid var(--accent); outline-offset: 2px; }
.slot-pick input { position: absolute; opacity: 0; width: 1px; height: 1px; }
.slot-pick .hint { color: var(--muted); font-size: 0.9rem; }
.slot-pick .error { color: var(--error); font-size: 0.9rem; }

.badge {
  display: inline-grid; place-items: center;
  min-width: 28px; height: 28px; padding-inline: 6px; border-radius: 8px;
  font-weight: 700; font-size: 0.9rem;
}
.badge.src-0 { background: var(--a-soft); color: var(--a); }
.badge.src-1 { background: var(--b-soft); color: var(--b); }

.slot-title { font-weight: 600; }

.slot-file {
  display: grid;
  grid-template-columns: 64px 1fr;
  gap: 12px;
  padding: 12px;
  align-items: center;
}
.slot-file .thumb { width: 64px; }
.slot-file .meta { min-width: 0; }
.slot-file .name { font-weight: 600; overflow-wrap: anywhere; }
.slot-file .info { color: var(--muted); font-size: 0.9rem; }
.slot-file .tools { display: flex; gap: 6px; margin-top: 8px; flex-wrap: wrap; }

.tool {
  display: inline-flex; align-items: center; gap: 4px;
  min-height: 36px; padding: 4px 10px;
  border: 1px solid var(--border); border-radius: 8px;
  background: var(--surface); cursor: pointer; font-size: 0.85rem;
}
.tool:hover { background: var(--surface-2); }

.swap {
  align-self: center;
  width: 44px; height: 44px; border-radius: 50%;
  border: 1px solid var(--border); background: var(--surface);
  font-size: 1.2rem; cursor: pointer; box-shadow: var(--shadow);
}
.swap:disabled { opacity: 0.4; cursor: default; }

/* ---------- strategies ---------- */

.strategies {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 10px;
}
.strategy {
  display: block; position: relative;
  padding: 12px 14px 12px 44px;
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  cursor: pointer;
}
.strategy input {
  position: absolute; left: 14px; top: 15px;
  width: 18px; height: 18px; margin: 0; accent-color: var(--accent);
}
.strategy:has(input:checked) { border-color: var(--accent); }
.strategy:has(input:focus-visible) { outline: 2px solid var(--accent); outline-offset: 2px; }
.strategy .label { font-weight: 600; }
.strategy .pattern { display: block; font-family: ui-monospace, "SF Mono", Consolas, monospace; font-size: 0.9rem; margin-top: 2px; }
.strategy .desc { display: block; color: var(--muted); font-size: 0.85rem; margin-top: 4px; }

.warning {
  margin: 10px 0 0; padding: 10px 12px;
  background: var(--warn-bg); color: var(--warn-text);
  border-radius: 8px; font-size: 0.9rem;
}

/* ---------- preview ---------- */

.preview {
  list-style: none; margin: 0; padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(104px, 1fr));
  gap: 12px;
}
.preview li { display: flex; flex-direction: column; gap: 4px; }
.preview .caption { display: flex; align-items: center; justify-content: space-between; font-size: 0.85rem; }
.preview .caption .pos { color: var(--muted); }
.preview .caption .badge { height: 22px; min-width: 0; font-size: 0.75rem; border-radius: 6px; }

.thumb {
  display: grid; place-items: center;
  aspect-ratio: 1 / 1.414;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  overflow: hidden;
  color: var(--muted); font-size: 0.8rem;
}
.thumb img { display: block; width: 100%; height: 100%; object-fit: contain; transition: transform 0.2s; }
.thumb.src-0 { border-bottom: 3px solid var(--a); }
.thumb.src-1 { border-bottom: 3px solid var(--b); }

.empty { color: var(--muted); margin: 0; }
.hint { color: var(--muted); font-size: 0.9rem; margin: 0 0 10px; }

/* ---------- tool chooser ---------- */

.tools {
  list-style: none; margin: 24px 0 0; padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 12px;
}
.tool-card {
  display: grid; grid-template-columns: auto 1fr; column-gap: 14px; row-gap: 4px;
  height: 100%; padding: 16px;
  background: var(--surface); color: inherit; text-decoration: none;
  border: 2px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.tool-card:hover, .tool-card:focus-visible { border-color: var(--accent); }
.tool-icon {
  grid-row: span 2;
  display: grid; place-items: center;
  width: 44px; height: 44px; border-radius: 10px;
  background: var(--a-soft); color: var(--a); font-size: 1.4rem;
}
.tool-name { font-weight: 600; font-size: 1.05rem; }
.tool-desc { color: var(--muted); font-size: 0.9rem; }

/* ---------- single file, settings (handout, pages & poster) ---------- */

.slot.single.filled { border-color: var(--accent); }
.slot.single .slot-file { grid-template-columns: 112px 1fr; }
.slot.single .slot-file .thumb { width: 112px; }

.settings {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(210px, 1fr));
  gap: 10px 16px;
  padding: 14px;
  background: var(--surface);
  border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.settings .settings { padding: 12px 0 0; border: 0; box-shadow: none; background: none; }
.field { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
.field.wide { grid-column: 1 / -1; }
.field[hidden] { display: none; }
.field > label { font-size: 0.9rem; font-weight: 600; }
.field .control { display: flex; align-items: center; gap: 10px; }
.field select, .field input[type="text"], .field input[type="number"] {
  width: 100%; min-height: 40px; padding: 4px 10px;
  background: var(--surface); border: 1px solid var(--border); border-radius: 8px;
}
.field input[type="range"] { flex: 1; min-width: 0; accent-color: var(--accent); }
.field output { min-width: 4.5em; text-align: right; font-variant-numeric: tabular-nums; font-size: 0.9rem; }
.field.check { flex-direction: row; align-items: center; gap: 8px; min-height: 40px; cursor: pointer; }
.field.check input { width: 18px; height: 18px; margin: 0; accent-color: var(--accent); }
.field.check-text { flex-direction: row; align-items: center; gap: 10px; }
.field.check-text input[type="text"] { flex: 1; }
.field.disabled { opacity: 0.5; }
.field-group summary { cursor: pointer; font-weight: 600; font-size: 0.9rem; min-height: 32px; }
.field select:focus, .field input:focus-visible { outline: 2px solid var(--accent); outline-offset: 1px; }

/* ---------- page list (handout, pages & poster) ---------- */

.slides {
  list-style: none; margin: 0; padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}
.slides .item { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
.thumb-button {
  display: block; width: 100%; padding: 0; border: 0; background: none;
  cursor: pointer; border-radius: 6px;
}
.thumb-button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.slides .slide .thumb { border-bottom: 3px solid var(--a); }
.slides .excluded .thumb { opacity: 0.35; border-bottom-color: var(--border); filter: grayscale(1); }
.slides .excluded .pos { text-decoration: line-through; }
.slides .blank .thumb { border-style: dashed; font-size: 1.4rem; }
.slides .caption { display: flex; justify-content: space-between; gap: 6px; font-size: 0.85rem; }
.slides .caption .pos { font-weight: 600; }
.slides .caption .where { color: var(--muted); }
.item-tools { display: flex; gap: 6px; }

.icon {
  display: inline-grid; place-items: center;
  min-width: 36px; height: 32px; padding: 0 8px;
  border: 1px solid var(--border); border-radius: 8px;
  background: var(--surface); cursor: pointer; font-size: 0.95rem;
}
.icon:hover { background: var(--surface-2); }
.icon:disabled { opacity: 0.35; cursor: default; }
.icon.active { background: var(--accent); color: var(--accent-text); border-color: var(--accent); }

.marker.break {
  grid-column: 1 / -1;
  display: flex; align-items: center; gap: 10px;
  color: var(--accent); font-weight: 600; font-size: 0.9rem;
}
.marker.break::after { content: ""; flex: 1; order: 1; border-top: 2px dashed var(--accent); }
.marker.break .icon { order: 2; }

/* ---------- live preview (handout, pages & poster) ---------- */

.preview.pages { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.preview.pages .thumb { background: #fff; border-radius: 2px; }
.preview.stale { opacity: 0.6; transition: opacity 0.2s; }
#warnings .warning { margin: 0 0 10px; }

/* ---------- action bar ---------- */

.actions {
  position: sticky; bottom: 0;
  display: flex; gap: 10px;
  padding-block: 12px calc(12px + env(safe-area-inset-bottom));
  background: var(--bg);
  border-top: 1px solid var(--border);
}
.filename { flex: 1; min-width: 0; }
.filename input {
  width: 100%; height: 48px; padding: 0 12px;
  background: var(--surface);
  border: 1px solid var(--border); border-radius: 10px;
}
.filename input:focus { outline: 2px solid var(--accent); outline-offset: 1px; }

.primary {
  height: 48px; padding: 0 20px;
  background: var(--accent); color: var(--accent-text);
  border: 0; border-radius: 10px;
  font-weight: 600; cursor: pointer; white-space: nowrap;
}
.primary:disabled { opacity: 0.45; cursor: default; }

.noscript { text-align: center; padding: 16px; }

/* ---------- organise pages ---------- */

.src-0 { --src: var(--a); --src-soft: var(--a-soft); }
.src-1 { --src: var(--b); --src-soft: var(--b-soft); }
.src-2 { --src: var(--c); --src-soft: var(--c-soft); }
.src-3 { --src: var(--d); --src-soft: var(--d-soft); }
.src-4 { --src: var(--e); --src-soft: var(--e-soft); }
.src-5 { --src: var(--f); --src-soft: var(--f-soft); }

.files { list-style: none; margin: 0 0 10px; padding: 0; display: grid; gap: 8px; }
.files:empty { display: none; }
.file-row {
  display: grid; grid-template-columns: auto 1fr auto; gap: 12px; align-items: center;
  padding: 10px 12px;
  background: var(--surface);
  border: 1px solid var(--border); border-left: 4px solid var(--src); border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.file-row .badge { background: var(--src-soft); color: var(--src); }
.file-row .meta { display: flex; flex-direction: column; min-width: 0; }
.file-row .name { font-weight: 600; overflow-wrap: anywhere; }
.file-row .info { color: var(--muted); font-size: 0.9rem; }
.slot.add-files.compact, .slot.add-files.compact .slot-pick { min-height: 72px; }
.slot.add-files.compact .slot-pick { padding: 10px; }

.list-tools { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 10px; }
.tool:disabled { opacity: 0.4; cursor: default; }
.tool.active { background: var(--accent); color: var(--accent-text); border-color: var(--accent); }

.bulk {
  position: sticky; top: 0; z-index: 5;
  display: grid; gap: 6px;
  margin-bottom: 10px; padding: 10px;
  background: var(--surface-2);
  border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.bulk[hidden] { display: none; }
.bulk-row { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; }
.bulk-count { font-weight: 600; font-size: 0.9rem; margin-right: 4px; }
.move-to { display: inline-flex; align-items: center; gap: 6px; font-size: 0.85rem; }
.move-to input {
  width: 5em; min-height: 36px; padding: 2px 8px;
  background: var(--surface); border: 1px solid var(--border); border-radius: 8px;
}

.arrange {
  list-style: none; margin: 0; padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 14px 12px;
}
.arrange .item { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
.arrange .thumb { background: #fff; border-bottom: 3px solid var(--src, var(--border)); }
.arrange .blank .thumb { border-style: dashed; border-bottom-width: 1px; }
.arrange .excluded .thumb { opacity: 0.35; filter: grayscale(1); }
.arrange .excluded .pos { text-decoration: line-through; }
.arrange .selected .thumb-button { outline: 3px solid var(--accent); outline-offset: 2px; }
.arrange .selected .thumb::after {
  content: "✓"; position: absolute; top: 4px; right: 4px;
  display: grid; place-items: center; width: 24px; height: 24px; border-radius: 50%;
  background: var(--accent); color: var(--accent-text); font-size: 0.85rem; font-weight: 700;
}
.arrange .partial .thumb-button { outline: 2px dashed var(--accent); outline-offset: 2px; }
.arrange .thumb { position: relative; }
.arrange .run .thumb-button { padding: 0 8px 8px 0; }
.arrange .run .thumb {
  box-shadow: 4px 4px 0 -1px var(--surface), 4px 4px 0 0 var(--src), 8px 8px 0 -1px var(--surface), 8px 8px 0 0 var(--src);
}
.arrange .caption { display: flex; justify-content: space-between; gap: 6px; font-size: 0.85rem; }
.arrange .caption .pos { font-weight: 600; color: var(--src, inherit); white-space: nowrap; }
.arrange .caption .where { color: var(--muted); text-align: right; }
.arrange .item-tools { display: flex; gap: 4px; }
.arrange .item-tools .icon { min-width: 36px; height: 36px; padding: 0 6px; }
.grip { margin-left: auto; cursor: grab; touch-action: none; font-size: 1.1rem; }
.arrange .dragging { opacity: 0.4; }

.drag-ghost {
  position: fixed; left: 0; top: 0; z-index: 50;
  pointer-events: none; opacity: 0.85;
  list-style: none;
  transform-origin: 0 0;
  filter: drop-shadow(0 6px 14px rgb(0 0 0 / 0.25));
}
.drop-marker {
  position: fixed; z-index: 49; width: 4px;
  background: var(--accent); border-radius: 2px;
  pointer-events: none;
}
body.drag-sorting { cursor: grabbing; user-select: none; -webkit-user-select: none; }

.preview.pages.arrange-preview { grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); }

/* ---------- zoom buttons of the thumbnail grids ---------- */

.zoom { display: inline-flex; gap: 4px; margin-left: auto; }
.zoom .icon { min-width: 36px; height: 32px; font-size: 1.1rem; font-weight: 600; }
ol[data-cols] { grid-template-columns: repeat(var(--cols), minmax(0, 1fr)) !important; }

/* ---------- phones ---------- */

@media (max-width: 600px) {
  .slots { grid-template-columns: 1fr; }
  .swap { justify-self: center; transform: rotate(90deg); }
  .preview { grid-template-columns: repeat(auto-fill, minmax(84px, 1fr)); gap: 10px; }
  .slides { gap: 10px; }
  .arrange, .preview.pages.arrange-preview { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px 10px; }
  .settings { grid-template-columns: 1fr; }
  .slot.single .slot-file { grid-template-columns: 88px 1fr; }
  .slot.single .slot-file .thumb { width: 88px; }
  .top { grid-template-columns: auto 1fr auto; }
  .top h1 { grid-column: 1 / -1; grid-row: 2; }
  .top .language { grid-column: 3; grid-row: 1; }
  .actions { flex-direction: column; }
  .primary { width: 100%; }
}