:root {
  --bg: #111111;
  --panel: #1b1b1d;
  --panel-2: #232327;
  --line: #34343a;
  --ink: #f4f4f5;
  --muted: #a1a1aa;
  --accent: #e8483f;
  --accent-ink: #ffffff;
  --page: #fafaf7;
  --page-ink: #18181b;
  --radius: 14px;
  --gap: 16px;
  font-synthesis: none;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
}

/* ---------- Top bar ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 16px;
  padding-top: calc(12px + env(safe-area-inset-top));
  background: rgba(17,17,17,0.9);
  backdrop-filter: saturate(140%) blur(8px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; min-width: 0; flex: 1 1 auto; }
.brand-mark { color: var(--accent); font-size: 22px; line-height: 1; flex: none; }
.brand-name { font-weight: 700; letter-spacing: 0.2px; font-size: 17px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; min-width: 0; }
.topbar-actions { display: flex; align-items: center; gap: 10px; flex: none; }

.paper-select { display: flex; align-items: center; gap: 6px; color: var(--muted); font-size: 13px; }
.paper-select select {
  background: var(--panel-2);
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 9px;
  padding: 8px 10px;
  font-size: 14px;
}

.btn {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--panel-2);
  color: var(--ink);
  font-size: 15px;
  font-weight: 600;
  padding: 10px 16px;
  border-radius: 11px;
  cursor: pointer;
  white-space: nowrap;
}
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn[disabled] { opacity: 0.55; cursor: progress; }

/* ---------- Layout ---------- */
.layout {
  max-width: 1100px;
  margin: 0 auto;
  padding: var(--gap);
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--gap);
}
@media (min-width: 920px) {
  .layout { grid-template-columns: 1.1fr 0.9fr; align-items: start; }
  .preview { position: sticky; top: 84px; }
}

.editor { display: flex; flex-direction: column; gap: var(--gap); }

/* ---------- Cards ---------- */
.card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
}
.card-title {
  margin: 0 0 12px;
  font-size: 15px;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 8px;
}
.page-tag {
  font-size: 11px;
  font-weight: 600;
  color: var(--muted);
  background: var(--panel-2);
  border: 1px solid var(--line);
  padding: 2px 8px;
  border-radius: 999px;
}
.spread-card .page-tag { text-transform: none; }

.cover-fields { display: flex; flex-direction: column; gap: 8px; margin-bottom: 12px; }
.txt {
  width: 100%;
  background: var(--panel-2);
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 11px 12px;
  font-size: 15px;
}
.txt::placeholder { color: #6b6b73; }
.txt-title { font-size: 18px; font-weight: 700; }
.txt-area { resize: vertical; min-height: 64px; font-family: inherit; margin-top: 12px; }
.qr-input { margin-top: 8px; font-size: 13px; }

/* ---------- Slots ---------- */
.slot {
  position: relative;
  border: 1.5px dashed var(--line);
  border-radius: 12px;
  background: var(--panel-2);
  overflow: hidden;
}
.slot-portrait { aspect-ratio: 2.75 / 4.25; max-width: 220px; }
.file-input {
  position: absolute;
  inset: 0;
  opacity: 0;
  width: 100%;
  height: 100%;
  cursor: pointer;
  z-index: 2;
}
.slot-label {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 6px;
  color: var(--muted);
  text-align: center;
  padding: 10px;
  pointer-events: none;
}
.slot-icon { font-size: 28px; line-height: 1; }
.slot-text { font-size: 13px; }
.slot.has-image .slot-label { display: none; }
.slot-clear {
  position: absolute;
  top: 8px;
  right: 8px;
  z-index: 3;
  border: none;
  background: rgba(0,0,0,0.62);
  color: #fff;
  font-size: 12px;
  font-weight: 600;
  padding: 6px 10px;
  border-radius: 999px;
  cursor: pointer;
}
.slot canvas, .slot img { display: block; width: 100%; height: 100%; object-fit: cover; }

/* ---------- Spreads ---------- */
.spread-card { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; }
.spread-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 12px;
}
.spread-head h2 { margin: 0; font-size: 15px; font-weight: 700; display: flex; align-items: center; gap: 8px; }

.spread-stage {
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2px;
  aspect-ratio: 5.5 / 4.25;
  background: var(--line);
  border-radius: 10px;
  overflow: hidden;
}
.spread-stage.is-landscape { gap: 0; }
.spread-page {
  position: relative;
  background: var(--panel-2);
  overflow: hidden;
}
.spread-page .file-input { z-index: 2; }
.spread-page canvas, .spread-page img { display: block; width: 100%; height: 100%; object-fit: cover; }
.spread-page .slot-label { position: absolute; inset: 0; }
.spread-page.has-image .slot-label { display: none; }

/* center fold line on the spread preview */
.spread-stage::after {
  content: "";
  position: absolute;
  top: 0; bottom: 0; left: 50%;
  width: 1px;
  transform: translateX(-0.5px);
  background: rgba(255,255,255,0.25);
  pointer-events: none;
}

.spread-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-top: 10px;
}
.spread-hint { font-size: 12px; color: var(--muted); }
.spread-clear {
  border: 1px solid var(--line);
  background: var(--panel-2);
  color: var(--muted);
  font-size: 12px;
  font-weight: 600;
  padding: 6px 10px;
  border-radius: 999px;
  cursor: pointer;
}
.spread-clear[hidden] { display: none; }
.spread-head-btns { display: flex; gap: 6px; align-items: center; margin-left: auto; }
.icon-btn {
  border: 1px solid var(--line); background: var(--panel-2); color: var(--ink);
  font-size: 13px; font-weight: 600; padding: 5px 10px; border-radius: 8px; cursor: pointer;
}
.icon-btn:hover { background: var(--line); }
.drag-grip { font-size: 18px; color: var(--muted); cursor: grab; user-select: none; padding: 0 4px; }
.spread-card.dragging { opacity: 0.4; }
.spread-card.drag-target { outline: 2px solid var(--accent); }
.captions { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin-top: 10px; }
.captions .txt { font-size: 13px; padding: 8px 10px; }
.cap-col { display: flex; flex-direction: column; gap: 4px; }
.page-fit-row { display: flex; gap: 4px; }
.fused-upload { margin-top: 8px; }
.upload-btn {
  display: inline-flex; align-items: center; gap: 6px; cursor: pointer;
  border: 1px dashed var(--line); background: var(--panel-2); color: var(--muted);
  font-size: 13px; padding: 8px 14px; border-radius: 10px; width: 100%; justify-content: center;
}
.upload-btn input[type=file] { display: none; }
.upload-btn:hover { color: var(--ink); border-color: var(--muted); }
.slot.drag-over, .spread-page.drag-over, .fused-upload.drag-over { outline: 2px solid var(--accent); }

/* ---------- Preview booklet ---------- */
.preview {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
}
.preview-title { margin: 0 0 4px; font-size: 15px; font-weight: 700; }
.preview-hint { margin: 0 0 14px; font-size: 12px; color: var(--muted); }
.booklet { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; }
.mini {
  background: var(--page);
  color: var(--page-ink);
  aspect-ratio: 2.75 / 4.25;
  border-radius: 6px;
  overflow: hidden;
  position: relative;
  box-shadow: 0 1px 0 rgba(0,0,0,0.4);
}
.mini canvas, .mini img { width: 100%; height: 100%; object-fit: cover; display: block; }
.mini .mini-num {
  position: absolute;
  bottom: 4px;
  right: 6px;
  font-size: 10px;
  color: var(--muted);
  background: rgba(255,255,255,0.7);
  border-radius: 4px;
  padding: 0 4px;
}
.mini-cover {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 8px;
  gap: 3px;
}
.mini-cover .mc-title { font-weight: 700; font-size: 13px; line-height: 1.15; }
.mini-cover .mc-sub { font-size: 9px; color: #52525b; }
.mini-cover .mc-author { font-size: 9px; color: #52525b; margin-top: auto; }
.mini-back { font-size: 8px; color: #52525b; padding: 8px; line-height: 1.3; white-space: pre-wrap; word-break: break-word; }

/* ---------- Section controls ---------- */
.section-controls { display: flex; flex-direction: column; gap: 8px; margin-top: 12px; padding-top: 12px; border-top: 1px solid var(--line); }
.ctrl-row { display: flex; align-items: center; gap: 10px; min-height: 32px; }
.ctrl-col { display: flex; flex-direction: column; gap: 8px; }
.ctrl-indent { padding-left: 12px; border-left: 2px solid var(--line); }
.ctrl-label { font-size: 12px; color: var(--muted); font-weight: 600; min-width: 72px; flex: none; }
.btn-group { display: flex; gap: 2px; }
.seg-btn {
  border: 1px solid var(--line); background: var(--panel-2); color: var(--muted);
  font-size: 12px; font-weight: 600; padding: 5px 10px; border-radius: 8px; cursor: pointer;
}
.seg-btn.active { background: var(--accent); border-color: var(--accent); color: #fff; }
.seg-btn.sm { padding: 3px 8px; font-size: 11px; }
.ctrl-slider { flex: 1; accent-color: var(--accent); height: 4px; }
.ctrl-check { width: 18px; height: 18px; accent-color: var(--accent); cursor: pointer; }
.ctrl-color { width: 36px; height: 28px; padding: 2px; border: 1px solid var(--line); border-radius: 6px; background: var(--panel-2); cursor: pointer; }
.ctrl-select {
  background: var(--panel-2); color: var(--ink); border: 1px solid var(--line);
  border-radius: 9px; padding: 6px 8px; font-size: 13px; flex: 1;
}
.ctrl-reset {
  border: 1px solid var(--line); background: var(--panel-2); color: var(--muted);
  font-size: 11px; font-weight: 600; padding: 4px 8px; border-radius: 6px; cursor: pointer;
}
.qr-input { margin-top: 8px; font-size: 13px; }

/* ---------- Extra buttons ---------- */
.btn-ghost { background: transparent; border-color: var(--line); color: var(--muted); }
.btn-ghost:hover { color: var(--ink); }
.btn-danger { background: #7f1d1d; border-color: #991b1b; color: #fff; }

/* ---------- Confirm dialog ---------- */
.confirm-overlay {
  position: fixed; inset: 0; background: rgba(0,0,0,0.7); z-index: 100;
  display: flex; align-items: center; justify-content: center;
}
.confirm-overlay[hidden] { display: none; }
.confirm-box {
  background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 24px; max-width: 340px; width: 90%; display: flex; flex-direction: column; gap: 16px;
}
.confirm-msg { margin: 0; font-size: 15px; color: var(--ink); }
.confirm-actions { display: flex; gap: 10px; justify-content: flex-end; }

/* ---------- How-to ---------- */
.howto {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px 16px;
}
.howto summary { cursor: pointer; font-weight: 600; font-size: 14px; }
.howto ol { margin: 12px 0 0; padding-left: 20px; color: var(--muted); font-size: 14px; line-height: 1.5; }
.howto li { margin-bottom: 8px; }
.howto strong { color: var(--ink); }

/* ---------- Toast ---------- */
.toast {
  position: fixed;
  left: 50%;
  bottom: calc(20px + env(safe-area-inset-bottom));
  transform: translateX(-50%);
  background: #000;
  color: #fff;
  border: 1px solid var(--line);
  padding: 11px 18px;
  border-radius: 999px;
  font-size: 14px;
  z-index: 50;
  box-shadow: 0 8px 30px rgba(0,0,0,0.5);
}

/* ---------- Footer ---------- */
.footer { text-align: center; color: var(--muted); font-size: 12px; padding: 24px 16px calc(32px + env(safe-area-inset-bottom)); }

@media (max-width: 480px) {
  .topbar { gap: 8px; padding-left: 12px; padding-right: 12px; }
  .topbar-actions { gap: 6px; }
  .paper-select span { display: none; }
  .paper-select select { padding: 8px 6px; font-size: 13px; }
  .btn { padding: 9px 12px; font-size: 14px; }
  .slot-portrait { max-width: none; }
  .brand-name { font-size: 16px; }
}
@media (max-width: 360px) {
  .brand-name { display: none; }
}