:root {
  /* palette — from bachng23.dev (warm parchment / espresso ink / ember) */
  --ink: #26251e;
  --parchment: #f7f7f4;
  --stone: #e6e5e0;
  --sand: #d9d5cf;
  --clay: #7a7974;
  --ash: #8f8e89;
  --smoke: #a1a19f;
  --charcoal: #141414;
  --ember: #f54e00;
  --accent: #f54e00;

  /* worksheet-specific */
  --grid: #3a392f;        /* cell lines */
  --guide-rgb: 210 59 59; /* red 田字格 cross, faded with --trace-opacity */
  --cell: 15mm;           /* overwritten inline by JS */
  --trace-opacity: 0.25;  /* overwritten inline by JS */

  --font-cjk-ui: "PingFang TC", "Noto Sans TC", "Microsoft JhengHei", "Heiti TC", sans-serif;
  --font-sans: "Inter", var(--font-cjk-ui), ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-brand: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --font-serif: "Inter", Georgia, serif;

  --radius: 8px;
  --radius-pill: 9999px;
  --shadow-paper: 0 18px 50px rgba(38,37,30,.12), 0 6px 18px rgba(38,37,30,.08),
                  0 0 0 1px rgba(38,37,30,.05);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--ink);
  background: var(--parchment);
  letter-spacing: 0;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  display: flex;
  align-items: flex-start;
}

html[lang="zh-Hant"] body {
  font-family: "Inter", var(--font-cjk-ui);
}

/* Kai handwriting font for all Chinese glyphs */
.hanzi {
  font-family: "LXGW WenKai TC", "Kaiti TC", "Kaiti SC", "KaiTi", "BiauKai",
               "DFKai-SB", "STKaiti", serif;
}

/* ---------------- Loading splash ---------------- */
#loader {
  position: fixed;
  inset: 0;
  z-index: 9999;
  background: var(--parchment);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  transition: opacity .5s ease, visibility .5s;
}
#loader.done { opacity: 0; visibility: hidden; }
.loader-text {
  position: relative;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(34px, 9vw, 92px);
  letter-spacing: 0;
  line-height: 1;
  padding-bottom: 0.22em;   /* room for descenders so the fill covers them */
  white-space: nowrap;
}
.loader-text .base { color: var(--sand); }
.loader-text .fill {
  position: absolute;
  inset: 0;
  color: var(--ink);
  clip-path: inset(100% 0 0 0);
  animation: fillUp 1.8s ease forwards;
}
@keyframes fillUp {
  from { clip-path: inset(100% 0 0 0); }
  to   { clip-path: inset(0 0 0 0); }
}
.loader-pct {
  margin-top: 18px;
  font-family: var(--font-mono);
  font-size: clamp(12px, 1.6vw, 16px);
  letter-spacing: 0;
  color: var(--clay);
}
@media print { #loader { display: none !important; } }

/* ---------------- Language switcher ---------------- */
.lang-switch {
  position: fixed;
  top: 16px; right: 18px;
  z-index: 50;
  display: flex;
  background: var(--parchment);
  border: 1px solid var(--sand);
  border-radius: var(--radius-pill);
  overflow: hidden;
}
.lang-switch button {
  flex: 0 0 auto;
  padding: 7px 14px;
  border: none;
  background: transparent;
  color: var(--clay);
  font-family: var(--font-sans);
  font-weight: 500;
  font-size: 12px;
  letter-spacing: 0;
  cursor: pointer;
  border-radius: 0;
  transition: color .2s ease, background .2s ease;
}
.lang-switch button:hover { color: var(--ember); }
.lang-switch button.active { background: var(--ink); color: var(--parchment); }

/* ---------------- Control panel ---------------- */
.panel {
  width: 348px;
  min-width: 348px;
  height: 100vh;
  height: 100dvh;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 22px 22px 18px;
  background: var(--stone);
  border-right: 1px solid var(--sand);
  position: sticky;
  top: 0;
}
.panel::-webkit-scrollbar { width: 6px; }
.panel::-webkit-scrollbar-thumb {
  background: rgba(122, 121, 116, .28);
  border-radius: var(--radius-pill);
}
.panel h1 {
  margin: 0 0 14px;
  display: flex;
  flex-direction: column;
  gap: 5px;
}
.brand-line {
  display: flex;
  align-items: center;
  gap: 8px;
  min-width: 0;
}
.brand-icon {
  width: 28px;
  height: 28px;
  flex: 0 0 auto;
  object-fit: contain;
  display: block;
}
.panel h1 b {
  font-family: var(--font-brand);
  font-weight: 500;
  font-size: 24px;
  letter-spacing: 0;
}
.panel h1 > span:not(.brand-line) {
  font-family: var(--font-sans);
  font-size: 10px;
  font-weight: 400;
  letter-spacing: 0;
  text-transform: none;
  color: var(--clay);
  line-height: 1.45;
}

.field { display: flex; flex-direction: column; margin-bottom: 10px; }
.field > span {
  font-size: 11.5px;
  font-weight: 500;
  letter-spacing: 0;
  margin-bottom: 5px;
  color: var(--ink);
}
.field small {
  font-size: 10.5px;
  color: var(--clay);
  margin-top: 5px;
  line-height: 1.35;
  white-space: pre-line;
}

textarea, input, select {
  font: inherit;
  font-size: 12.5px;
  padding: 8px 10px;
  border: 1px solid var(--sand);
  border-radius: var(--radius);
  background: #fff;
  color: var(--ink);
  width: 100%;
  transition: border-color .15s ease, box-shadow .15s ease;
}
textarea:focus, input:focus, select:focus {
  outline: none;
  border-color: var(--ember);
  box-shadow: 0 0 0 3px rgba(245, 78, 0, .12);
}
textarea {
  resize: none;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.4;
  min-height: 122px;
}
.row2 { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }

.checks { display: flex; flex-direction: column; gap: 8px; margin: 4px 0 16px; font-size: 13px; }
.checks label { display: flex; align-items: center; gap: 8px; cursor: pointer; }

.actions { display: flex; gap: 10px; margin-bottom: 10px; }

button {
  flex: 1;
  padding: 10px 14px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-family: var(--font-sans);
  font-weight: 500;
  font-size: 13px;
  letter-spacing: 0;
  cursor: pointer;
  transition: transform .2s ease, opacity .2s ease, background .2s ease, color .2s ease;
  white-space: nowrap;
}
button.primary { background: var(--ink); color: var(--parchment); }
button.primary:hover { opacity: .9; transform: translateY(-1px); }
button#print { background: var(--ember); color: #fff; }
button#print:hover { opacity: .92; transform: translateY(-1px); }
button#openFile {
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--ink);
  width: 100%;
  font-size: 12.5px;
  white-space: normal;
  line-height: 1.35;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
}
button#openFile:hover { background: var(--parchment); transform: translateY(-1px); }
button:disabled { opacity: .55; cursor: default; transform: none; }
.hint { display: block; font-size: 11px; color: var(--clay); line-height: 1.5; }

/* ---------------- Vocab loader ---------------- */
.vocab {
  border: 1px solid var(--sand);
  border-radius: var(--radius);
  padding: 12px 14px;
  margin-bottom: 12px;
  background: #fff;
  min-width: 0;
}
.vocab-title {
  font-family: var(--font-sans);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0;
  text-transform: none;
  color: var(--clay);
  margin: 0 0 10px;
  line-height: 1.35;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.vocab .field { margin-bottom: 8px; }
.vocab .actions { margin: 8px 0 0; }
.vocab button { padding: 9px 10px; }
#vinfo { font-size: 10.5px; color: var(--clay); display: block; margin: 6px 0 0; }
.sel-all { display: flex; align-items: center; gap: 7px; font-size: 11.5px; font-weight: 500; margin: 8px 0 6px; cursor: pointer; }
.sel-all input { width: auto; flex: 0 0 auto; }
.lesson-list {
  max-height: 118px; overflow-y: auto;
  border: 1px solid var(--sand); border-radius: var(--radius);
  padding: 6px 9px; background: var(--parchment);
}
.lesson-item {
  display: flex; align-items: center; gap: 8px;
  font-size: 11.5px; padding: 2px 4px; cursor: pointer; border-radius: 4px;
  transition: background .12s ease;
}
.lesson-item:hover { background: var(--stone); }
.lesson-item input { width: auto; }

/* ---------------- Worksheet area ---------------- */
.sheet {
  flex: 1;
  padding: 40px 32px 64px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}
.placeholder { color: var(--clay); margin-top: 72px; font-size: 14px; font-family: var(--font-mono); }

.page {
  width: 210mm;
  min-height: 297mm;
  background: #fff;
  padding: 14mm 12mm;
  box-shadow: var(--shadow-paper);
}
.page-title {
  text-align: center;
  font-family: var(--font-serif);
  font-size: 22px;
  font-weight: 400;
  margin: 0 0 8mm;
  color: var(--ink);
}

/* A character block = one entry */
.block { margin-bottom: 4mm; page-break-inside: avoid; }
.block-head {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding-left: 1mm;
  margin-bottom: 1.5mm;
}
.block-head .head-hanzi { font-size: 15pt; font-weight: 700; color: var(--ink); }
.block-head .py { font-size: 12pt; font-weight: 600; color: var(--ember); }
.block-head .mean { font-size: 11pt; color: var(--clay); }

/* stroke-order demonstration strip */
.stroke-strip { display: flex; flex-wrap: wrap; gap: 1mm; margin: 0 0 1.5mm 0; }
.stroke-cell {
  width: 9mm; height: 9mm;
  border: 0.5px solid #cfcbc4;
  background: #fff;
  flex: 0 0 auto;
}
.stroke-cell.sgrid {
  background-image:
    linear-gradient(to right, transparent calc(50% - 0.3px), #f0d2d2 calc(50% - 0.3px), #f0d2d2 calc(50% + 0.3px), transparent calc(50% + 0.3px)),
    linear-gradient(to bottom, transparent calc(50% - 0.3px), #f0d2d2 calc(50% - 0.3px), #f0d2d2 calc(50% + 0.3px), transparent calc(50% + 0.3px));
}
.stroke-svg { width: 100%; height: 100%; display: block; }

.grid-row {
  display: flex;
  width: fit-content;
  border-left: 1px solid var(--grid);
}
.grid-row.row-top { border-top: 1px solid var(--grid); }
.cell {
  width: var(--cell);
  height: var(--cell);
  border-right: 1px solid var(--grid);
  border-bottom: 1px solid var(--grid);
  position: relative;
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
.cell.tian::before,
.cell.tian::after { content: ""; position: absolute; pointer-events: none; }
.cell.tian::before {
  left: 50%;
  top: 0;
  bottom: 0;
  border-left: 0.6px dashed rgb(var(--guide-rgb) / var(--trace-opacity));
}
.cell.tian::after {
  top: 50%;
  left: 0;
  right: 0;
  border-top: 0.6px dashed rgb(var(--guide-rgb) / var(--trace-opacity));
}

.cell .glyph {
  position: relative; z-index: 2; line-height: 1;
  font-size: calc(var(--cell) * 0.82); user-select: none;
}
.cell .glyph.solid { color: var(--ink); }
.cell .glyph.trace { color: var(--ink); opacity: var(--trace-opacity); }
.cell .glyph-svg { width: 86%; height: 86%; display: block; position: relative; z-index: 2; }
.cell .glyph-svg.trace { opacity: var(--trace-opacity); }
.cell.ref { background-color: #fafafa; }
.cell.ref .glyph { color: var(--ink); }

/* ---------------- Import modal ---------------- */
.modal-back {
  position: fixed; inset: 0; z-index: 100;
  background: rgba(20, 20, 20, .45);
  display: flex; align-items: center; justify-content: center;
  padding: 20px;
}
.modal {
  background: var(--parchment); border-radius: 14px; padding: 24px;
  width: min(560px, 94vw); max-height: 88vh; overflow-y: auto;
  border: 1px solid var(--sand);
  box-shadow: 0 24px 60px rgba(20,20,20,.35);
}
.modal h3 { margin: 0 0 4px; font-size: 18px; font-weight: 500; }
.modal h3 .fn { color: var(--ember); }
.modal .msub { margin: 0 0 14px; font-size: 12px; color: var(--clay); }
.modal .actions { margin-top: 16px; }
.modal #impCancel { background: var(--stone); color: var(--ink); border-color: var(--sand); }
.modal #impCancel:hover { background: var(--sand); }
.file-picker-modal {
  width: min(420px, 92vw);
}
.file-drop {
  width: 100%;
  min-height: 142px;
  border: 1px dashed var(--ash);
  border-radius: var(--radius);
  background: #fff;
  color: var(--ink);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 18px;
  white-space: normal;
  text-align: center;
}
.file-drop span {
  font-size: 14px;
  font-weight: 500;
}
.file-drop small {
  color: var(--clay);
  font-size: 11px;
  line-height: 1.45;
}
.file-drop:hover,
.file-drop.dragging {
  background: var(--parchment);
  border-color: var(--ember);
  transform: none;
}
.imp-preview {
  margin-top: 12px; padding: 12px; background: #fff; border: 1px solid var(--sand);
  border-radius: var(--radius); font-family: var(--font-mono);
  font-size: 13px; max-height: 200px; overflow-y: auto;
}
.imp-skip { display: flex; align-items: center; gap: 7px; font-size: 12px; margin-top: 12px; cursor: pointer; }
.imp-skip input { width: auto; }
.imp-preview .imp-count { font-size: 11px; color: var(--clay); margin-bottom: 6px; font-family: var(--font-sans); }
.imp-preview > div + div { margin-top: 2px; }

/* ---------------- Credits ---------------- */
.print-footer { display: none; }
.web-credit {
  position: fixed;
  bottom: 12px; right: 16px;
  z-index: 40;
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: 0;
  color: var(--smoke);
  pointer-events: none;
}

@media (max-width: 700px) {
  html,
  body {
    overflow-x: hidden;
  }

  body {
    display: block;
  }

  .lang-switch {
    position: absolute;
    top: 12px;
    right: 14px;
  }

  .panel {
    position: relative;
    width: 100%;
    min-width: 0;
    height: auto;
    min-height: 100vh;
    min-height: 100svh;
    min-height: 100dvh;
    overflow: visible;
    padding: 22px 14px 18px;
    border-right: none;
  }

  .panel h1 {
    padding-right: 132px;
  }

  .panel h1 > span:not(.brand-line) {
    font-size: 9.5px;
  }

  .vocab {
    padding: 12px;
  }

  .sheet {
    padding: 20px 10px 40px;
    overflow-x: auto;
    align-items: flex-start;
  }

  .actions {
    flex-wrap: wrap;
  }

  .modal-back {
    padding: 14px;
  }

  .modal {
    width: 100%;
    max-height: calc(100dvh - 28px);
    padding: 18px;
  }

  .modal .row2 {
    grid-template-columns: 1fr;
    gap: 8px;
  }
}

@media (min-width: 701px) and (max-height: 820px) {
  .panel {
    padding-top: 16px;
    padding-bottom: 14px;
  }

  .panel h1 {
    margin-bottom: 10px;
    gap: 3px;
  }

  .brand-icon {
    width: 24px;
    height: 24px;
  }

  .panel h1 b {
    font-size: 22px;
  }

  .panel h1 > span:not(.brand-line) {
    font-size: 9.5px;
    line-height: 1.3;
  }

  .field {
    margin-bottom: 8px;
  }

  .field > span {
    margin-bottom: 4px;
  }

  .field small {
    margin-top: 4px;
    line-height: 1.25;
  }

  textarea,
  input,
  select {
    padding-top: 7px;
    padding-bottom: 7px;
  }

  textarea {
    min-height: 96px;
    line-height: 1.32;
  }

  .vocab {
    padding: 10px 12px;
    margin-bottom: 10px;
  }

  .vocab-title {
    margin-bottom: 7px;
    font-size: 10.5px;
  }

  .vocab .field {
    margin-bottom: 6px;
  }

  .sel-all {
    margin: 6px 0 5px;
  }

  .lesson-list {
    max-height: 92px;
    padding-top: 5px;
    padding-bottom: 5px;
  }

  .lesson-item {
    padding-top: 1px;
    padding-bottom: 1px;
  }

  #vinfo {
    margin-top: 4px;
  }

  .vocab .actions {
    margin-top: 6px;
  }

  .actions {
    margin-bottom: 8px;
  }

  button {
    padding-top: 8px;
    padding-bottom: 8px;
  }
}

@media (min-width: 701px) and (max-height: 700px) {
  .panel {
    padding-top: 12px;
    padding-bottom: 12px;
  }

  .panel h1 {
    margin-bottom: 8px;
  }

  .lesson-list {
    max-height: 74px;
  }

  textarea {
    min-height: 76px;
  }

  .field small {
    font-size: 10px;
  }
}

@media (max-width: 390px) {
  .panel {
    padding-left: 10px;
    padding-right: 10px;
  }

  .panel h1 {
    padding-right: 118px;
  }

  .panel h1 b {
    font-size: 22px;
  }

  .lang-switch button {
    padding: 6px 10px;
    font-size: 11px;
  }

  textarea {
    min-height: 104px;
  }

  .lesson-list {
    max-height: 104px;
  }

  button {
    padding-left: 10px;
    padding-right: 10px;
  }
}

/* ---------------- Print ---------------- */
@media print {
  @page { size: A4; margin: 0; }
  body { background: #fff; display: block; }
  .no-print { display: none !important; }
  .sheet { padding: 0; gap: 0; }
  .page { box-shadow: none; width: 210mm; min-height: 297mm; page-break-after: always; }
  .page:last-child { page-break-after: auto; }
  .print-footer {
    display: block; position: fixed; bottom: 4mm; right: 8mm;
    font-family: var(--font-mono); font-size: 8pt; color: #d6d6d6;
  }
}