:root {
  --sand:       #D4B896;
  --tan:        #C4A882;
  --tan-dark:   #B5956E;
  --brown-mid:  #8B7355;
  --brown-dark: #5C3D2E;
  --espresso:   #3B1F0E;
  --ochre:      #B5860D;
  --saddle:     #8B4513;
  --cream:      #F0E4C8;
  --page-bg:    #1E1208;
  --toolbar-bg: #2A1608;
  --panel-bg:   #261408;
  --border:     #5C3D2E;
  --thickness:  80px;
}

@media (max-width: 600px) {
  :root { --thickness: 52px; }
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: var(--page-bg);
  color: var(--cream);
  font-family: 'Courier New', Courier, monospace;
  font-size: 13px;
}

/* ─── Layout grid ─── */
#app {
  display: grid;
  grid-template-columns: var(--thickness) 1fr;
  grid-template-rows: var(--thickness) 1fr auto auto;
  width: 100vw;
  height: 100vh;       /* fallback for browsers without dvh */
  height: 100dvh;      /* dynamic: shrinks when mobile browser chrome is visible */
  min-height: 0;       /* prevent grid blowout */
}

/* ─── Corner square — matches ruler yellow ─── */
#corner {
  grid-column: 1;
  grid-row: 1;
  background: linear-gradient(135deg, #F5EE96, #E2D870);
  border-right: 1px solid #BFB86A;
  border-bottom: 1px solid #BFB86A;
  display: flex;
  align-items: center;
  justify-content: center;
}
#corner svg {
  opacity: 0.55;
}

/* ─── Rulers ─── */
#h-ruler-wrap {
  grid-column: 2;
  grid-row: 1;
  overflow: hidden;
  cursor: crosshair;
}
#v-ruler-wrap {
  grid-column: 1;
  grid-row: 2;
  overflow: hidden;
  cursor: crosshair;
}
#h-canvas, #v-canvas {
  display: block;
  touch-action: none;
}

/* ─── Main area ─── */
#main-area {
  grid-column: 2;
  grid-row: 2;
  min-height: 0;       /* allow 1fr row to shrink if needed */
  position: relative;
  cursor: crosshair;
  background: var(--page-bg);
  overflow: hidden;
  touch-action: none;
}

#crosshair-h {
  position: absolute;
  left: 0; right: 0;
  height: 1px;
  background: rgba(181, 134, 13, 0.35);
  pointer-events: none;
  transform: translateY(-0.5px);
}
#crosshair-v {
  position: absolute;
  top: 0; bottom: 0;
  width: 1px;
  background: rgba(181, 134, 13, 0.35);
  pointer-events: none;
  transform: translateX(-0.5px);
}

#readout {
  position: absolute;
  bottom: 10px;
  right: 14px;
  background: rgba(42, 22, 8, 0.88);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 4px 10px;
  font-size: 12px;
  color: var(--cream);
  pointer-events: none;
  letter-spacing: 0.03em;
}
#readout span {
  color: var(--ochre);
  font-weight: bold;
}

/* ─── Toolbar ─── */
#toolbar {
  grid-column: 1 / -1;
  grid-row: 3;
  background: var(--toolbar-bg);
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 10px;
  flex-wrap: wrap;
}

.tool-group {
  display: flex;
  align-items: center;
  gap: 3px;
  padding-right: 10px;
  border-right: 1px solid var(--border);
}
.tool-group:last-child {
  border-right: none;
  margin-left: auto;
}

.btn-tool {
  background: var(--panel-bg);
  color: var(--cream);
  border: 1px solid var(--brown-mid);
  border-radius: 3px;
  padding: 3px 9px;
  cursor: pointer;
  font-family: inherit;
  font-size: 12px;
  letter-spacing: 0.04em;
  transition: background 0.12s, border-color 0.12s, color 0.12s;
  user-select: none;
}
.btn-tool:hover {
  background: var(--brown-dark);
  border-color: var(--tan);
  color: var(--sand);
}
.btn-tool.active {
  background: var(--saddle);
  border-color: var(--ochre);
  color: var(--cream);
}

.label-inline {
  font-size: 11px;
  color: var(--tan);
  white-space: nowrap;
}

#ppi-input {
  width: 52px;
  background: var(--panel-bg);
  color: var(--cream);
  border: 1px solid var(--brown-mid);
  border-radius: 3px;
  padding: 2px 5px;
  font-family: inherit;
  font-size: 12px;
  text-align: right;
}
#ppi-input:focus {
  outline: none;
  border-color: var(--ochre);
}

.tool-brand {
  font-size: 13px;
  color: var(--tan);
  letter-spacing: 0.08em;
  padding-right: 0;
  border-right: none;
}
.tool-brand strong {
  color: var(--ochre);
}

/* ─── Status / command bar ─── */
#status-bar {
  grid-column: 1 / -1;
  grid-row: 4;
  background: var(--panel-bg);
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 4px 10px;
  min-height: 28px;
}

#markers-info {
  flex: 1;
  font-size: 11px;
  color: var(--tan);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

#cmd-wrap {
  display: flex;
  align-items: center;
  gap: 4px;
}
#cmd-input {
  width: 160px;
  background: var(--panel-bg);
  color: var(--cream);
  border: 1px solid var(--brown-mid);
  border-radius: 3px;
  padding: 2px 6px;
  font-family: inherit;
  font-size: 12px;
}
#cmd-input::placeholder {
  color: var(--brown-mid);
}
#cmd-input:focus {
  outline: none;
  border-color: var(--ochre);
}
#cmd-run {
  background: var(--saddle);
  color: var(--cream);
  border: 1px solid var(--ochre);
  border-radius: 3px;
  padding: 2px 8px;
  cursor: pointer;
  font-family: inherit;
  font-size: 11px;
}
#cmd-run:hover {
  background: var(--ochre);
  color: var(--espresso);
}
#cmd-result {
  font-size: 11px;
  color: var(--ochre);
  min-width: 160px;
}

/* ─── PPI badge ─── */
.ppi-badge {
  font-size: 11px;
  color: var(--ochre);
  letter-spacing: 0.03em;
  white-space: nowrap;
}

/* ─── Calibration overlay ─── */
#cal-overlay {
  position: fixed;
  inset: 0;
  z-index: 1000;
  background: rgba(10, 5, 0, 0.82);
  display: flex;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(3px);
}
#cal-overlay.hidden { display: none; }

#cal-dialog {
  background: var(--toolbar-bg);
  border: 1px solid var(--brown-mid);
  border-radius: 8px;
  padding: 24px 28px 20px;
  width: min(480px, 94vw);
  max-height: 90vh;
  overflow-y: auto;
  color: var(--cream);
  font-family: 'Courier New', monospace;
}

#cal-dialog h2 {
  font-size: 17px;
  color: var(--sand);
  margin-bottom: 6px;
  letter-spacing: 0.05em;
}
.cal-sub {
  font-size: 12px;
  color: var(--tan);
  margin-bottom: 16px;
}
.cal-hint {
  font-size: 11px;
  color: var(--brown-mid);
  margin-top: 8px;
}
.cal-hint.hidden { display: none; }

/* Tabs */
#cal-tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 14px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 8px;
}
.cal-tab {
  background: none;
  border: 1px solid var(--border);
  border-radius: 3px 3px 0 0;
  color: var(--tan);
  padding: 4px 12px;
  cursor: pointer;
  font-family: inherit;
  font-size: 12px;
  transition: background 0.1s, color 0.1s;
}
.cal-tab.active {
  background: var(--saddle);
  border-color: var(--ochre);
  color: var(--cream);
}

/* Tab panels */
.cal-panel { display: block; }
.cal-panel.hidden { display: none; }

/* Presets */
.preset-category {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 5px;
  margin-bottom: 9px;
}
.preset-cat-label {
  font-size: 10px;
  color: var(--brown-mid);
  width: 46px;
  flex-shrink: 0;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.btn-preset {
  background: var(--panel-bg);
  color: var(--cream);
  border: 1px solid var(--brown-mid);
  border-radius: 3px;
  padding: 4px 10px;
  cursor: pointer;
  font-family: inherit;
  font-size: 12px;
  transition: background 0.1s, border-color 0.1s;
}
.btn-preset:hover, .btn-preset.selected {
  background: var(--saddle);
  border-color: var(--ochre);
  color: var(--cream);
}

/* Custom size tab */
.cal-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 12px 0 4px;
}
#cal-custom-in {
  width: 90px;
  background: var(--panel-bg);
  color: var(--cream);
  border: 1px solid var(--brown-mid);
  border-radius: 3px;
  padding: 5px 8px;
  font-family: inherit;
  font-size: 13px;
}
#cal-custom-in:focus { outline: none; border-color: var(--ochre); }
.cal-unit-label {
  font-size: 12px;
  color: var(--tan);
}
#btn-cal-custom, #btn-cal-card {
  background: var(--saddle);
  color: var(--cream);
  border: 1px solid var(--ochre);
  border-radius: 3px;
  padding: 5px 14px;
  cursor: pointer;
  font-family: inherit;
  font-size: 12px;
}
#btn-cal-custom:hover, #btn-cal-card:hover {
  background: var(--ochre);
  color: var(--espresso);
}

/* Credit card calibrator */
#cal-card-wrap {
  margin: 14px 0 10px;
  overflow: hidden;
  user-select: none;
}
#cal-card-bar {
  position: relative;
  height: 54px;
  background: linear-gradient(135deg, var(--tan), var(--tan-dark));
  border: 1px solid var(--brown-mid);
  border-radius: 5px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: ew-resize;
  min-width: 60px;
  max-width: 100%;
  touch-action: none;
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.15);
}
.cal-card-label {
  font-size: 11px;
  color: var(--espresso);
  pointer-events: none;
  letter-spacing: 0.04em;
}
#cal-card-handle {
  position: absolute;
  right: 0;
  top: 0; bottom: 0;
  width: 20px;
  background: var(--saddle);
  border-radius: 0 5px 5px 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  color: var(--cream);
  cursor: ew-resize;
  user-select: none;
}

/* Computed result */
#cal-computed {
  margin-top: 10px;
  font-size: 12px;
  color: var(--ochre);
}

/* Skip button */
.btn-cal-skip {
  display: block;
  margin-top: 16px;
  background: none;
  border: none;
  color: var(--brown-mid);
  cursor: pointer;
  font-family: inherit;
  font-size: 11px;
  text-decoration: underline;
}
.btn-cal-skip:hover { color: var(--tan); }

/* ─── Fraction group visibility ─── */
.frac-group {
  display: none;
}
.frac-group.visible {
  display: flex;
}

/* ─── Mobile / small screen ─── */
@media (max-width: 600px) {
  #toolbar {
    gap: 4px;
    padding: 4px 6px;
    overflow-x: auto;
    flex-wrap: nowrap;
    -webkit-overflow-scrolling: touch;
  }
  .tool-group {
    flex-shrink: 0;
    padding-right: 7px;
  }
  /* Hide hint text and brand on small screens */
  .tool-brand,
  .hint-group {
    display: none;
  }
  .btn-tool {
    padding: 4px 8px;
    font-size: 11px;
  }
  #ppi-input {
    width: 44px;
  }
  /* Stack status bar on mobile */
  #status-bar {
    flex-wrap: wrap;
    gap: 4px;
    padding: 4px 8px;
  }
  #cmd-wrap {
    width: 100%;
  }
  #cmd-input {
    flex: 1;
    width: auto;
    min-width: 0;
  }
  #cmd-result {
    min-width: 0;
    flex: 1;
  }
  /* Readout: top-left on mobile so it doesn't hide content */
  #readout {
    top: 6px;
    left: 6px;
    bottom: auto;
    right: auto;
    font-size: 11px;
    padding: 3px 7px;
  }
}