:root {
  --bg: #eef3f9;
  --panel-bg: #ffffff;
  --panel-border: #d8e0ee;
  --text: #111827;
  --muted: #6b7280;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --secondary: #e5e7eb;
  --secondary-hover: #d1d5db;
  --shadow: 0 12px 30px rgba(15, 23, 42, 0.08);

  --a4-width: 210mm;
  --a4-height: 297mm;
  --big-cell-cm: 1.5;
  --big-cell-mm: calc(var(--big-cell-cm) * 10mm);
  --small-cell-mm: calc(var(--big-cell-mm) / 2);
  --page-margin-mm: var(--big-cell-mm);
  --grid-line: 1px;
  --trace-color: #c7cdd6;

  --font-cjk: "Huninn", "Noto Sans TC", "Microsoft JhengHei", sans-serif;
  --font-latin: "Comfortaa", "Segoe UI", Arial, sans-serif;
  --font-ui: "Segoe UI", "Microsoft JhengHei", sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-ui);
}

body {
  min-height: 100vh;
}

button,
input {
  font: inherit;
}

button {
  cursor: pointer;
}

.app-shell {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 360px minmax(0, 1fr);
}

.control-panel {
  background: var(--panel-bg);
  border-right: 1px solid var(--panel-border);
  padding: 24px;
  display: grid;
  align-content: start;
  gap: 16px;
}

.panel-title {
  margin: 0;
  font-size: 28px;
  line-height: 1.2;
}

.panel-subtitle {
  margin: -6px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.control-card {
  background: #ffffff;
  border: 1px solid var(--panel-border);
  border-radius: 16px;
  box-shadow: var(--shadow);
  padding: 16px;
}

.control-label,
.section-title {
  display: block;
  margin: 0 0 10px;
  font-size: 15px;
  font-weight: 700;
}

.section-title {
  margin-bottom: 8px;
}

.inline-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 10px;
}

.char-input,
#bigCellSizeCm {
  width: 100%;
  border: 1px solid #cbd5e1;
  border-radius: 12px;
  background: #ffffff;
  padding: 12px 14px;
  color: var(--text);
  outline: none;
}

.char-input:focus,
#bigCellSizeCm:focus {
  border-color: #93c5fd;
  box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.12);
}

#addCharBtn,
#exportPdfBtn,
.secondary-btn {
  appearance: none;
  border: 0;
  border-radius: 12px;
  padding: 12px 16px;
  font-weight: 700;
  transition: background-color 0.15s ease, transform 0.06s ease, opacity 0.15s ease;
}

#addCharBtn,
#exportPdfBtn {
  background: var(--primary);
  color: #ffffff;
}

#addCharBtn:hover,
#exportPdfBtn:hover {
  background: var(--primary-hover);
}

.secondary-btn {
  width: 100%;
  background: var(--secondary);
  color: #111827;
}

.secondary-btn:hover {
  background: var(--secondary-hover);
}

#addCharBtn:active,
#exportPdfBtn:active,
.secondary-btn:active {
  transform: translateY(1px);
}

#addCharBtn:disabled,
#exportPdfBtn:disabled,
.secondary-btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.helper-text,
.status-message,
.preview-subtitle {
  margin: 8px 0 0;
  color: var(--muted);
  line-height: 1.6;
  white-space: pre-line;
}

.rule-list {
  margin: 0;
  padding-left: 20px;
  color: #334155;
  line-height: 1.8;
}

.preview-panel {
  min-width: 0;
  padding: 24px;
  display: grid;
  grid-template-rows: auto minmax(0, 1fr);
  gap: 12px;
}

.preview-toolbar h2 {
  margin: 0;
  font-size: 22px;
}

.preview-stage {
  position: relative;
  min-width: 0;
  min-height: calc(100vh - 84px);
  border: 1px solid var(--panel-border);
  border-radius: 20px;
  background: linear-gradient(180deg, #e2e8f0 0%, #cbd5e1 100%);
  overflow: auto;
  padding: 20px;
}

.preview-scaler {
  margin: 0 auto;
  position: relative;
}

.preview-transform {
  transform-origin: top left;
}

.a4-page {
  width: var(--a4-width);
  height: var(--a4-height);
  background: #ffffff;
  box-shadow: 0 20px 50px rgba(15, 23, 42, 0.16);
  position: relative;
  overflow: hidden;
}

.page-ruler {
  position: absolute;
  top: 4mm;
  left: 4mm;
  display: inline-flex;
  flex-direction: column;
  gap: 1mm;
  align-items: flex-start;
  z-index: 2;
}

.page-ruler__bar {
  width: 1cm;
  height: 0;
  border-top: 1px solid #000000;
}

.page-ruler__label {
  font-size: 3mm;
  line-height: 1;
  color: #000000;
}

.page-content {
  position: absolute;
  inset: 0;
  padding: var(--page-margin-mm);
  display: flex;
  flex-wrap: wrap;
  align-content: flex-start;
  gap: 0;
  overflow: hidden;
}

/* 修正隔線跑掉：改用真正的 CSS Grid + 1px 黑色 gap 當格線 */
.trace-module {
  width: calc(var(--big-cell-mm) + (var(--small-cell-mm) * 2));
  height: var(--big-cell-mm);
  display: grid;
  grid-template-columns: var(--big-cell-mm) var(--small-cell-mm) var(--small-cell-mm);
  grid-template-rows: var(--small-cell-mm) var(--small-cell-mm);
  flex: 0 0 auto;
  margin-right: calc(var(--grid-line) * -1);
  margin-bottom: calc(var(--grid-line) * -1);
}

.trace-char {
  display: flex;
  align-items: center;
  justify-content: center;
  background: #ffffff;
  color: var(--trace-color);
  line-height: 1;
  user-select: none;
  pointer-events: none;
  overflow: hidden;
  box-sizing: border-box;
}

.trace-char--large {
  grid-column: 1;
  grid-row: 1 / span 2;
  font-size: calc(var(--big-cell-mm) * 0.96);
  border: 1px solid #000000;
}

.trace-char--small {
  font-size: calc(var(--small-cell-mm) * 0.96);
}

.trace-char--small-1 {
  grid-column: 2;
  grid-row: 1;
  border-top: 1px solid #000000;
  border-right: 1px solid #000000;
  border-bottom: 1px solid #000000;
}

.trace-char--small-2 {
  grid-column: 3;
  grid-row: 1;
  border-top: 1px solid #000000;
  border-right: 1px solid #000000;
  border-bottom: 1px solid #000000;
}

.trace-char--small-3 {
  grid-column: 2;
  grid-row: 2;
  border-right: 1px solid #000000;
  border-bottom: 1px solid #000000;
}

.trace-char--small-4 {
  grid-column: 3;
  grid-row: 2;
  border-right: 1px solid #000000;
  border-bottom: 1px solid #000000;
}

.trace-char.font-cjk {
  font-family: var(--font-cjk);
  font-weight: 400;
}

.trace-char.font-latin {
  font-family: var(--font-latin);
  font-weight: 500;
}

.empty-state {
  position: absolute;
  inset: var(--page-margin-mm);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: #94a3b8;
  padding: 12mm;
  font-size: 5mm;
}

.empty-state.is-hidden {
  display: none;
}

.noscript-message {
  max-width: 900px;
  margin: 24px auto;
  padding: 16px 18px;
  background: #fff7ed;
  color: #9a3412;
  border: 1px solid #fdba74;
  border-radius: 12px;
}

@media (max-width: 1200px) {
  .app-shell {
    grid-template-columns: 1fr;
  }

  .control-panel {
    border-right: 0;
    border-bottom: 1px solid var(--panel-border);
  }

  .preview-stage {
    min-height: 70vh;
  }
}

@media (max-width: 768px) {
  .control-panel,
  .preview-panel {
    padding: 16px;
  }

  .panel-title {
    font-size: 24px;
  }

  .preview-stage {
    padding: 12px;
  }
}

@media print {
  html,
  body {
    background: #ffffff;
  }

  .control-panel,
  .preview-toolbar {
    display: none !important;
  }

  .app-shell,
  .preview-panel,
  .preview-stage,
  .preview-scaler,
  .preview-transform {
    display: block;
    margin: 0;
    padding: 0;
    border: 0;
    box-shadow: none;
    background: #ffffff;
    min-height: 0;
  }

  .a4-page {
    box-shadow: none;
    margin: 0;
  }
}