* { box-sizing: border-box; }
:root {
  --bg: #F1F4F8;
  --panel-bg: #FFFFFF;
  --input-bg: #F7F9FB;
  --border: #DCE2E8;
  --border-strong: #C3CBD4;
  --text: #22222F;
  --text-secondary: #606F7B;
  --text-muted: #8A94A0;
  --accent: #3F7BEF;
  --accent-hover: #2E68D8;
  --danger: #DA2A07;
  --success: #1A7F37;

  /* Canvas drawing colors, read by app.js so the plan matches the page theme */
  --canvas-bg: #FFFFFF;
  --room-stroke: #22222F;
  --clearance-fill: #EDF1F5;
  --row-block-fill: #FFFFFF;
  --row-label: #22222F;
  --brief-header: #22222F;
  --brief-body: #606F7B;
}
:root[data-theme="dark"] {
  --bg: #1B1E24;
  --panel-bg: #22262E;
  --input-bg: #1A1D23;
  --border: #3A4150;
  --border-strong: #4A5262;
  --text: #E6E8EC;
  --text-secondary: #B6BCC6;
  --text-muted: #7C8593;
  --accent: #4F8CFF;
  --accent-hover: #3F7BEF;
  --danger: #FF6B6B;
  --success: #7EE787;

  /* Canvas drawing colors deliberately excluded here — the drawing itself
     (and its printed/exported look) always stays white/light, regardless of
     the page theme; only --bg/--panel-bg/etc above follow dark mode. */
}
body {
  margin: 0;
  font-family: -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
}
.app {
  display: flex;
  /* Fills the viewport below the shared 56px sticky site header (see ../common.css). */
  height: calc(100vh - 56px);
}
.panel {
  width: 320px;
  flex-shrink: 0;
  background: var(--panel-bg);
  padding: 20px;
  overflow-y: auto;
  border-right: 1px solid var(--border);
}
.tabs {
  display: flex;
  gap: 0;
  margin-bottom: 20px;
  border-bottom: 1px solid var(--border);
}
.tab-btn {
  flex: 1;
  padding: 10px;
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
}
.tab-btn:hover {
  color: var(--text);
}
.tab-btn.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}
.tab-content {
  display: none;
}
.tab-content.active {
  display: block;
}
.panel h1 {
  font-size: 18px;
  margin: 0 0 16px;
  color: var(--text);
}
.panel h2 {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
  margin: 18px 0 8px;
}
.field {
  margin-bottom: 10px;
  flex: 1;
}
.field-row {
  display: flex;
  gap: 10px;
}
.field label {
  display: block;
  font-size: 12px;
  color: var(--text-secondary);
  margin-bottom: 4px;
}
.field input, .field select {
  width: 100%;
  padding: 6px 8px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--input-bg);
  color: var(--text);
  font-size: 13px;
}

/* ---- Spreadsheet-style Ready / Enter / Edit modes for number fields ---- */
.field input[type="number"] {
  caret-color: transparent; /* Ready mode: no visible cursor */
}
.field input[type="number"]:focus {
  outline: none;
}
.field input[type="number"].mode-ready:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(63, 123, 239, 0.25);
}
.field input[type="number"].mode-enter {
  caret-color: var(--accent); /* Enter mode: typing, cursor visible */
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(63, 123, 239, 0.25);
}
.field input[type="number"].mode-edit {
  caret-color: var(--success); /* Edit mode: in-place cursor, distinct color */
  border-color: var(--success);
  box-shadow: 0 0 0 2px rgba(26, 127, 55, 0.2);
}
.field input::placeholder {
  color: var(--text-muted);
}
/* Hide the number input spin arrows */
.field input[type="number"]::-webkit-inner-spin-button,
.field input[type="number"]::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}
.field input[type="number"] {
  -moz-appearance: textfield;
  appearance: textfield;
}
.hint {
  font-size: 11px;
  color: var(--text-secondary);
  margin: -4px 0 10px;
  line-height: 1.4;
}
.hint-warn {
  color: var(--danger);
  font-weight: 600;
}
.dim-label {
  font-size: 12px;
  color: var(--text-secondary);
  margin: 2px 0 4px;
}
.checkbox-field label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text);
  cursor: pointer;
}
.checkbox-field input {
  width: auto;
  accent-color: var(--accent);
}
.actions {
  margin-top: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
button {
  padding: 10px;
  border-radius: 6px;
  border: none;
  font-size: 14px;
  cursor: pointer;
  font-weight: 600;
}
#generateBtn {
  background: var(--accent);
  color: #fff;
}
#generateBtn:hover {
  background: var(--accent-hover);
}
#downloadBtn, #downloadPdfBtn {
  background: var(--input-bg);
  color: var(--text);
  border: 1px solid var(--border);
}
#downloadBtn:disabled, #downloadPdfBtn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}
#downloadBtn:not(:disabled):hover, #downloadPdfBtn:not(:disabled):hover {
  background: var(--border);
}
.message {
  margin-top: 12px;
  font-size: 12px;
  line-height: 1.4;
  white-space: pre-line;
  color: var(--text-secondary);
}
.message.error {
  color: var(--danger);
}
.message.ok {
  color: var(--success);
}
.canvas-wrap {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 20px;
  overflow: auto;
}
canvas {
  background: var(--canvas-bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  max-width: 100%;
  /* Left room below for the legend + ad banner without pushing either off-screen —
     see .ad-slot below — and above for the shared 56px sticky site header. */
  max-height: calc(100vh - 220px - 56px);
}
.legend {
  margin-top: 12px;
  display: flex;
  gap: 18px;
  font-size: 12px;
  color: var(--text-secondary);
}
.legend .swatch {
  display: inline-block;
  width: 12px;
  height: 12px;
  border-radius: 2px;
  margin-right: 6px;
  vertical-align: middle;
}
.swatch.rack { background: #4f8cff; }
.swatch.hot { background: #ff6b6b; }
.swatch.cold { background: #6bb8ff; }
.swatch.door { background: #b5651d; }
.swatch.clear { background: var(--clearance-fill); border: 1px solid var(--border); }
.swatch.wall { background: #9AA3AF; }
.swatch.hall { background: #FBF8F1; border: 1px solid var(--border); }

.results-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  margin-top: 16px;
}
.result-item {
  background: var(--input-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 12px;
}
.result-item label {
  display: block;
  font-size: 11px;
  color: var(--text-secondary);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.result-value {
  font-size: 24px;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 4px;
}
.result-note {
  font-size: 11px;
  font-weight: 600;
  color: var(--danger);
  margin-top: 4px;
}
.result-note:empty {
  display: none;
}
.result-formula {
  font-size: 11px;
  color: var(--text-muted);
  font-family: monospace;
  line-height: 1.4;
}
.sidebar-footer {
  margin-top: 16px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: 11px;
  color: var(--text-muted);
  line-height: 1.6;
}
.sidebar-footer a {
  font-size: 11px;
  color: var(--text-muted);
  text-decoration: none;
}
.sidebar-footer a:hover {
  color: var(--text-secondary);
  text-decoration: underline;
}
/* Reserved for a single AdSense banner below the drawing viewer — see the HTML
   comment above #adSlot for activation steps. Shows a dashed placeholder for now
   (.ad-slot-placeholder) so the reserved space is visible; delete that inner div
   once real ad markup replaces it. */
.ad-slot {
  width: 100%;
  max-width: 728px;
  margin-top: 16px;
}
.ad-slot-placeholder {
  height: 90px;
  border: 1.5px dashed var(--border-strong);
  border-radius: 6px;
  background: var(--input-bg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.ad-slot:empty {
  display: none;
}
button.full-width {
  width: 100%;
  margin-bottom: 20px;
}

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
}
.modal-overlay.hidden {
  display: none;
}
.modal {
  background: var(--panel-bg);
  border-radius: 10px;
  border: 1px solid var(--border);
  padding: 24px;
  width: 340px;
  max-width: 90vw;
}
.modal h2 {
  font-size: 16px;
  margin: 0 0 6px;
  color: var(--text);
}
.modal-actions {
  margin-top: 18px;
  display: flex;
  justify-content: flex-end;
  gap: 8px;
}
.modal-actions #arrayModalExport {
  background: var(--accent);
  color: #fff;
}
.modal-actions #arrayModalExport:hover {
  background: var(--accent-hover);
}
.modal-actions #arrayModalCancel {
  background: var(--input-bg);
  color: var(--text);
  border: 1px solid var(--border);
}
#arrayVCorridorWidthField.hidden {
  display: none;
}

/* ============ MOBILE LAYOUT (narrow screens only) ============
   Desktop shows the form panel and the canvas side by side — on a phone-width
   screen the panel is a fixed 320px, so the canvas gets squeezed into whatever's
   left (as little as 50-60px), making it unusable. Below this breakpoint, the
   panel and canvas become two separate full-width "screens" instead: the panel
   is what you see first, and tapping "Generate Layout" switches you to the
   canvas (via the .app.mobile-result class, toggled in app.js) — with its own
   "Back to Inputs" button and a duplicate set of the Download/Export buttons so
   you don't have to scroll back through the whole form to reach them. None of
   this runs above the breakpoint: .mobile-result and the buttons it shows have
   no effect there, since desktop never restyles based on that class. */
.back-to-inputs-btn,
.mobile-export-actions {
  display: none;
}
@media (max-width: 860px) {
  .app {
    flex-direction: column;
    height: calc(100vh - 56px);
  }
  .panel {
    width: 100%;
    height: 100%;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }
  .canvas-wrap {
    display: none;
    width: 100%;
    height: 100%;
  }
  .app.mobile-result .panel {
    display: none;
  }
  .app.mobile-result .canvas-wrap {
    display: flex;
    /* The base .canvas-wrap centers its content for the desktop side-by-side
       layout, which on a full-height mobile "screen" left a large empty gap
       above everything since the canvas + buttons are shorter than the
       viewport — start from the top and let it scroll instead. */
    justify-content: flex-start;
    overflow-y: auto;
  }
  canvas {
    /* The drawing keeps its real 1000x800 backing resolution (so exports and the
       drawing math are unaffected) — only how big it's SHOWN shrinks to fit. */
    width: 100%;
    height: auto;
    max-height: calc(100vh - 56px - 220px);
  }
  .back-to-inputs-btn {
    display: block;
    align-self: flex-start;
    margin-bottom: 12px;
    padding: 8px 14px;
    border-radius: 6px;
    border: 1px solid var(--border-strong);
    background: var(--input-bg);
    color: var(--text);
    font-size: 13px;
    cursor: pointer;
  }
  .back-to-inputs-btn:hover {
    background: var(--panel-bg);
  }
  .mobile-export-actions {
    display: flex;
    gap: 10px;
    width: 100%;
    max-width: 100%;
    margin-top: 12px;
  }
  .mobile-export-actions button {
    flex: 1;
  }
}

/* ============ INFO CONTENT (below the tool) ============
   Read-only reference content sitting below .app (see index.html) — plain
   article typography, no interaction with the tool's own state or CSS. */
.info-page {
  background: var(--bg);
  padding: 56px 24px 72px;
}
.info-page .info-inner {
  max-width: 760px;
  margin: 0 auto;
}
.info-page h2 {
  font-size: 1.2rem;
  color: var(--text);
  margin: 34px 0 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}
.info-page h2:first-child { margin-top: 0; }
.info-page p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
  margin: 0 0 14px;
}
.info-page ol, .info-page ul {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
  padding-left: 22px;
  margin: 0 0 14px;
}
.info-page strong { color: var(--text); }
.info-page details {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px 16px;
  margin-bottom: 10px;
  background: var(--panel-bg);
}
.info-page details p { margin: 10px 0 0; }
.info-page summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--text);
  font-size: 0.95rem;
}
.info-page summary::marker { color: var(--accent); }