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

body {
  margin: 0;
  font-family: system-ui, sans-serif;
  background: #fafafa;
  overflow: hidden;
}

#app {
  display: flex;
  height: 100vh;
  width: 100vw;
}

/* Sidebar */
#sidebar-left {
  width: 16rem;
  border-right: 1px solid #e4e4e7;
  background: #ffffff;
  padding: 1rem;
  overflow-y: auto;
  overscroll-behavior: contain;
}

.sidebar-logo {
  display: block;
  width: 100%;
  height: auto;
  margin-bottom: 1rem;
}

#sidebar-left h2 {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  margin: 0 0 1rem;
}

/* Canvas area */
main {
  position: relative;
  flex: 1;
  overflow: auto;
  background: #e4e4e7;
  padding: 2rem;
}

/* Letter page (8.5×11" at 96 PPI) — JS overrides width/height via inline style on init */
#canvas {
  width: 816px;
  height: 1056px;
  position: relative;
  margin: 0 auto;
  background-color: #ffffff;
  box-shadow: 0 25px 50px -12px rgb(0 0 0 / 0.25);
  --grid-line: rgba(55, 65, 81, 0.45);
  touch-action: none;
}

.engineering-grid {
  background-image:
    linear-gradient(to right, var(--grid-line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--grid-line) 1px, transparent 1px);
  background-size: 20px 20px;
}

/* Margin guide overlay */
#margin-guide,
.page-guide {
  position: absolute;
  border: 1px dashed rgba(59, 130, 246, 0.45);
  background-origin: border-box; /* grid tiles start at outer edge = margins.left/top, matching snap positions */
  pointer-events: none;
  z-index: 0;
}

/* Page separator bar rendered between sheet pages */
.page-sep {
  position: absolute;
  left: 0;
  right: 0;
  height: 14px;
  background: #cbd5e1;
  pointer-events: none;
  z-index: 9;
  display: flex;
  align-items: center;
  justify-content: flex-end;
}
.page-sep span {
  font-size: 9px;
  font-family: monospace;
  color: #475569;
  padding: 0 8px;
  letter-spacing: 0.04em;
}

/* Page numbers — always visible */
.page-num {
  position: absolute;
  font-size: 9px;
  font-family: system-ui, sans-serif;
  color: #475569;
  pointer-events: none;
  z-index: 0;
}

/* Draggable blocks */
.block {
  position: absolute;
  background: #ffffff;
  border: 1px solid #e4e4e7;
  box-shadow: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  padding: 1rem;
  cursor: grab;
  min-width: 10rem;
  z-index: 1;
  -webkit-user-select: none;
  user-select: none;
  touch-action: none;
}

.block.selected {
  border-color: #3b82f6;
  box-shadow: 0 0 0 2px rgba(59, 130, 246, 0.35);
}

/* Rubber-band selection rectangle */
#selection-band {
  position: absolute;
  border: 1px solid #3b82f6;
  background: rgba(59, 130, 246, 0.08);
  pointer-events: none;
  display: none;
  z-index: 9998;
}
#selection-band.active {
  display: block;
}

.block h2 {
  font-weight: 700;
  font-size: 0.875rem;
  margin: 0;
  outline: none;
}

/* Editable text content inside blocks */
.block-text {
  outline: none;
  min-height: 1.25rem;
  font-size: 0.875rem;
  line-height: 1.5;
  white-space: pre-wrap;
}

/* Markdown text block */
.text-block { min-width: 14rem; }

.md-view {
  min-height: 1.5rem;
  cursor: text;
  font-size: 0.875rem;
  line-height: 1.6;
  color: inherit;
}
.md-view p        { margin: 0 0 0.5em; }
.md-view p:last-child { margin-bottom: 0; }
.md-view h1       { font-size: 1.25rem; font-weight: 700; margin: 0.2em 0 0.4em; border-bottom: 1px solid #e4e4e7; padding-bottom: 0.2em; }
.md-view h2       { font-size: 1.05rem; font-weight: 700; margin: 0.2em 0 0.35em; }
.md-view h3       { font-size: 0.925rem; font-weight: 700; margin: 0.2em 0 0.3em; }
.md-view h4       { font-size: 0.875rem; font-weight: 700; margin: 0.2em 0 0.25em; }
.md-view strong   { font-weight: 700; }
.md-view em       { font-style: italic; }
.md-view code     { font-family: 'Courier New', monospace; font-size: 0.82em; background: #f3f4f6; border-radius: 3px; padding: 0.1em 0.3em; }
.md-view pre      { background: #f3f4f6; border-radius: 4px; padding: 0.6em 0.8em; overflow-x: auto; margin: 0.4em 0; }
.md-view pre code { background: none; padding: 0; font-size: 0.8rem; }
.md-view ul, .md-view ol { margin: 0.25em 0 0.5em 1.4em; padding: 0; }
.md-view li       { margin-bottom: 0.15em; }
.md-view hr       { border: none; border-top: 1px solid #e4e4e7; margin: 0.6em 0; }

.md-placeholder   { color: #a1a1aa; font-size: 0.8rem; font-style: italic; }

/* Blockquote */
.md-view blockquote {
  margin: 0.3em 0 0.5em 0;
  padding: 0.25em 0.75em;
  border-left: 3px solid #d1d5db;
  color: #6b7280;
  background: #f9fafb;
  border-radius: 0 3px 3px 0;
}
.md-view blockquote p { margin: 0; }

/* Links and images */
.md-view a { color: #2563eb; text-decoration: underline; }
.md-view a:hover { color: #1d4ed8; }
.md-view img.md-img { max-width: 100%; height: auto; border-radius: 3px; display: block; margin: 0.3em 0; }

/* Task list items */
.md-view .task-item { list-style: none; margin-left: -1.2em; }
.md-view .task-item input[type="checkbox"] { margin-right: 0.4em; vertical-align: middle; }

/* Inline math rendered by prettifyExpr inside markdown */
.md-math {
  font-family: 'Georgia', 'Times New Roman', serif;
  font-size: 0.9em;
}
.md-math sup { font-size: 0.65em; vertical-align: super; line-height: 0; }
.md-math sub { font-size: 0.65em; vertical-align: sub;   line-height: 0; }

/* Block / display math ($$...$$) */
.md-math-block {
  margin: 0.6em 0;
  padding: 0.4em 0;
  font-size: 1em;
}
/* Each equation row: left-spacer | centered equation | right number */
.eq-row {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 0.5em;
}
.eq-row > span:first-child { display: block; } /* left spacer */
.eq-num {
  text-align: right;
  font-size: 0.85em;
  color: #6b7280;
  white-space: nowrap;
  padding-right: 0.25em;
}
.eq-ref { color: #2563eb; text-decoration: none; font-size: 0.9em; }
.eq-ref:hover { text-decoration: underline; }
.eq-ref-missing { color: #ef4444; }

/* Markdown toolbar */
.md-toolbar {
  display: none;
  flex-wrap: wrap;
  gap: 2px;
  padding: 3px 4px;
  background: #f1f5f9;
  border: 1px solid #cbd5e1;
  border-bottom: none;
  border-radius: 3px 3px 0 0;
}
.md-toolbar button {
  padding: 1px 5px;
  font-size: 0.72rem;
  font-family: inherit;
  background: #ffffff;
  border: 1px solid #cbd5e1;
  border-radius: 3px;
  cursor: pointer;
  line-height: 1.5;
  color: #374151;
  min-width: 1.6em;
  text-align: center;
}
.md-toolbar button:hover { background: #e0e7ff; border-color: #6366f1; color: #4338ca; }
.tb-sep { width: 1px; background: #cbd5e1; margin: 2px 1px; align-self: stretch; }

.md-edit {
  display: none;
  width: 100%;
  min-height: 6rem;
  box-sizing: border-box;
  font-family: 'Courier New', monospace;
  font-size: 0.8rem;
  line-height: 1.5;
  border: 1px solid #3b82f6;
  border-radius: 3px;
  padding: 0.4rem 0.5rem;
  background: #f8faff;
  color: inherit;
  resize: none;
  outline: none;
  overflow: hidden;
}

/* Right-edge resize handle for text blocks */
.text-resize-handle {
  position: absolute;
  right: -22px;
  top: 0;
  bottom: 0;
  width: 44px;
  cursor: ew-resize;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2;
  touch-action: none;
}
.text-resize-handle::after {
  content: '';
  width: 3px;
  height: 24px;
  background: #d1d5db;
  border-radius: 2px;
  opacity: 0;
  transition: opacity 150ms;
}
.block:hover .text-resize-handle::after,
.block.selected .text-resize-handle::after {
  opacity: 1;
}

/* Placeholder for empty contenteditable elements */
[contenteditable][data-placeholder]:empty::before {
  content: attr(data-placeholder);
  color: #a1a1aa;
  pointer-events: none;
}

/* Math block layout */
.math-title {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: #71717a;
  margin-bottom: 0.5rem;
}

.math-row,
.math-result-row {
  display: flex;
  align-items: baseline;
  gap: 0.375rem;
  margin-bottom: 0.25rem;
}

.math-label {
  font-size: 0.8rem;
  font-style: italic;
  width: 3rem;
  flex-shrink: 0;
  color: #52525b;
}

.math-unit {
  font-size: 0.75rem;
  color: #a1a1aa;
}

.math-divider {
  border: none;
  border-top: 1px solid #e4e4e7;
  margin: 0.5rem 0;
}

.math-result-value {
  font-family: ui-monospace, monospace;
  font-size: 0.875rem;
  font-weight: 600;
}

/* Numeric input inside math blocks */
.block-input {
  width: 7rem;
  border: none;
  border-bottom: 1px solid #e4e4e7;
  outline: none;
  background: transparent;
  font-family: ui-monospace, monospace;
  font-size: 0.875rem;
  color: inherit;
  padding: 0 0.125rem;
  text-align: right;
}

/* Page size controls */
.page-controls {
  margin-bottom: 0.75rem;
}

.page-size-select {
  width: 100%;
  border: 1px solid #e4e4e7;
  border-radius: 0.25rem;
  background: #f3f4f6;
  font-family: inherit;
  font-size: 0.8rem;
  padding: 0.35rem 0.375rem;
  color: inherit;
  cursor: pointer;
  outline: none;
}

.page-size-select:focus {
  border-color: #3b82f6;
}

/* Margin heading + unit toggle row */
.margin-heading-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.5rem;
}

.margin-heading-row h2 {
  margin: 0;
}

.unit-toggle {
  padding: 0.15rem 0.45rem;
  border: 1px solid #e4e4e7;
  border-radius: 0.25rem;
  background: #f3f4f6;
  font-family: ui-monospace, monospace;
  font-size: 0.72rem;
  cursor: pointer;
  color: #52525b;
}

.unit-toggle:hover {
  border-color: #3b82f6;
  color: #2563eb;
}

/* Sidebar toggle button */
.view-toggle {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  width: 100%;
  padding: 0.375rem 0.5rem;
  margin-bottom: 0.75rem;
  background: #f3f4f6;
  border: 1px solid #e4e4e7;
  border-radius: 0.25rem;
  cursor: pointer;
  font-size: 0.8rem;
  font-family: inherit;
  color: #52525b;
  text-align: left;
}

.view-toggle.active {
  background: #eff6ff;
  border-color: #3b82f6;
  color: #2563eb;
}

.grid-density {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
  font-size: 0.75rem;
  color: #71717a;
}

.grid-density input[type="range"] {
  flex: 1;
  accent-color: #3b82f6;
  cursor: pointer;
}

/* Margin inputs grid */
.margin-inputs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.375rem;
  margin-bottom: 1rem;
}

.margin-field {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  font-size: 0.75rem;
  color: #71717a;
}

.margin-field input[type="number"] {
  width: 100%;
  border: 1px solid #e4e4e7;
  border-radius: 0.25rem;
  background: #f3f4f6;
  font-family: ui-monospace, monospace;
  font-size: 0.8rem;
  padding: 0.2rem 0.375rem;
  outline: none;
  color: inherit;
}

.margin-field input[type="number"]:focus {
  border-color: #3b82f6;
}

/* Cursor position readout */
#cursor-coords {
  font-family: ui-monospace, monospace;
  font-size: 0.8rem;
  color: #f97316;
  margin-bottom: 1rem;
}

/* Placement mode */
#canvas.placement-mode,
#canvas.placement-mode .block {
  cursor: crosshair;
}

/* Grid cursor: crosshair marker at current grid intersection */
#grid-cursor {
  position: absolute;
  width: 0;
  height: 0;
  pointer-events: none;
  z-index: 9999;
  top: 0;
  left: 0;
  overflow: visible;
}


/* Right-click context menu */
#ctx-menu {
  position: fixed;
  background: #ffffff;
  border: 1px solid #e4e4e7;
  border-radius: 0.25rem;
  box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1);
  padding: 0.25rem 0;
  z-index: 10000;
  display: none;
  min-width: 10rem;
}

#ctx-menu button {
  display: block;
  width: 100%;
  text-align: left;
  padding: 0.375rem 0.75rem;
  border: none;
  background: none;
  font-size: 0.8rem;
  font-family: inherit;
  cursor: pointer;
  color: #ef4444;
}

#ctx-menu button:hover {
  background: #fee2e2;
}

/* Formula section in context menu */
.ctx-section-header {
  padding: 0.2rem 0.75rem 0.1rem;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: #9ca3af;
  pointer-events: none;
}

.ctx-sep {
  margin: 0.25rem 0;
  border: none;
  border-top: 1px solid #e4e4e7;
}

/* Non-destructive context menu buttons (add actions) */
#ctx-menu button.ctx-neutral-btn {
  color: #374151;
}
#ctx-menu button.ctx-neutral-btn:hover {
  background: #f0fdf4;
  color: #059669;
}
#ctx-menu button.ctx-neutral-btn:disabled {
  color: #d1d5db;
  cursor: default;
}
#ctx-menu button.ctx-neutral-btn:disabled:hover {
  background: none;
}

/* ── Formula blocks ─────────────────────────────────────────────────────── */
.formula-block {
  min-width: 220px;
  font-size: 0.78rem;
}

/* Summary Block — identical to formula block but with a green left accent */
.summary-block {
  border-left: 3px solid #22c55e !important;
}

/* Sidebar badge marking section-only modules */
.module-section-badge {
  margin-left: auto;
  font-size: 0.65rem;
  font-weight: 700;
  color: #64748b;
  background: #e2e8f0;
  border-radius: 3px;
  padding: 0 4px;
  line-height: 1.4;
}

.formula-label {
  font-weight: 600;
  font-size: 0.78rem;
  padding: 2px 2px 3px;
  outline: none;
  border-bottom: 1px solid transparent;
  min-height: 1em;
}
.formula-label:focus { border-bottom-color: #3b82f6; }
.formula-label:empty::before {
  content: attr(data-placeholder);
  color: #9ca3af;
}

.formula-rows {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin: 4px 0 2px;
  position: relative;
}

/* Group wrapper for if/for...end blocks — desc and ref span the full block height */
.formula-block-group {
  display: flex;
  flex-direction: row;
}

.formula-block-inner {
  display: flex;
  flex-direction: column;
  flex: 1;
  gap: 2px;
}

/* Remove depth-based padding inside a group (structural nesting handles indentation) */
.formula-block-inner .formula-row {
  padding-left: 0;
}

.formula-row {
  display: flex;
  align-items: flex-start;
  gap: 0;
  padding-left: calc(var(--depth, 0) * 16px);
}

/* Control-flow rows align with the formula column when per-row desc column is present */
.formula-rows.has-any-row-desc .formula-row--control {
  padding-left: calc(186px + var(--depth, 0) * 16px);
}
/* Inside a group, per-row desc is always suppressed — no offset needed for control rows */
.formula-rows.has-any-row-desc .formula-block-inner .formula-row--control {
  padding-left: 0;
}

/* Description column */
.formula-desc-wrap {
  display: none;
  flex-shrink: 0;
  width: 180px;
  padding-right: 6px;
  margin-right: 6px;
  border-right: 1px solid #e4e4e7;
  align-self: stretch;
  flex-direction: column;
}

/* Group-level spanning desc/ref: blue border; shown when any row (incl. if/for) has annotation */
.formula-rows.has-any-desc .formula-block-group > .formula-desc-wrap {
  display: flex;
  border-right: 2px solid #93c5fd;
}
.formula-rows.has-any-ref .formula-block-group > .formula-ref-wrap {
  display: flex;
  align-items: flex-start;
  border-left: 2px solid #93c5fd;
}
/* Show desc column only when a row explicitly has a desc (> direct child — excludes group wrap) */
.formula-row.has-desc > .formula-desc-wrap { display: flex; }
/* When any regular row has a desc, show all row-level desc-wraps for alignment */
.formula-rows.has-any-row-desc .formula-row > .formula-desc-wrap { display: flex; }
/* Per-row desc-wraps are always suppressed inside groups — the group spanning wrap is the only annotation */
.formula-block-group .formula-row > .formula-desc-wrap { display: none !important; }

.formula-desc-cell {
  outline: none;
  cursor: text;
  font-size: 0.8rem;
  line-height: 1.5;
  color: #111827;
  padding: 1px 2px;
  border-bottom: 1px solid transparent;
  white-space: normal;
  word-break: break-word;
  font-family: system-ui, sans-serif;
  flex: 1;
}
.formula-desc-cell:focus {
  font-family: 'Courier New', monospace;
  font-size: 0.74rem;
  color: inherit;
  border-bottom: 1px solid #3b82f6;
}
.formula-desc-cell:empty::before {
  content: attr(data-placeholder);
  color: #d1d5db;
  font-style: italic;
  pointer-events: none;
}
.formula-desc-cell strong { font-weight: 700; }
.formula-desc-cell em     { font-style: italic; }
.formula-desc-cell code   { font-family: 'Courier New', monospace; font-size: 0.85em;
                            background: #f3f4f6; border-radius: 2px; padding: 0 2px; }
.formula-desc-cell .md-math { font-family: 'Georgia', serif; font-size: 0.85em; }

/* Reference column (right of formula) */
.formula-ref-wrap {
  display: none;
  flex-shrink: 0;
  width: 150px;
  padding-left: 6px;
  margin-left: 6px;
  border-left: 1px solid #e4e4e7;
  align-self: stretch;
}
.formula-row.has-ref > .formula-ref-wrap { display: flex; align-items: flex-start; }
/* When any regular row has a ref, show all row-level ref-wraps for alignment */
.formula-rows.has-any-row-ref .formula-row > .formula-ref-wrap { display: flex; align-items: flex-start; }
/* Per-row ref-wraps are always suppressed inside groups — the group spanning wrap is the only annotation */
.formula-block-group .formula-row > .formula-ref-wrap { display: none !important; }

.formula-ref-cell {
  outline: none;
  cursor: text;
  font-size: 0.8rem;
  line-height: 1.5;
  color: #111827;
  padding: 1px 2px;
  border-bottom: 1px solid transparent;
  white-space: normal;
  word-break: break-word;
  font-family: 'Courier New', monospace;
  flex: 1;
  align-self: stretch;
}
.formula-ref-cell:focus {
  color: inherit;
  border-bottom: 1px solid #3b82f6;
}
.formula-ref-cell:empty::before {
  content: attr(data-placeholder);
  color: #d1d5db;
  font-style: italic;
  pointer-events: none;
}

/* Right side: formula + result */
.formula-expr-side {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 4px;
  min-width: 0;
}

/* Single cell: shows rendered math when unfocused, raw text when focused */
.formula-cell {
  flex: 1;
  min-width: 0;
  outline: none;
  cursor: text;
  padding: 1px 2px;
  border-bottom: 1px solid transparent;
  line-height: 1.5;
  white-space: normal;
  overflow-wrap: break-word;
  overflow: visible;
  /* Unfocused: serif for rendered math */
  font-family: 'Georgia', 'Times New Roman', serif;
  font-size: 0.8rem;
}
.formula-cell:focus {
  /* Focused: monospace for editing raw text */
  font-family: 'Courier New', monospace;
  font-size: 0.74rem;
  border-bottom-color: #3b82f6;
}
.formula-cell:hover:not(:focus) { border-bottom-color: #d4d4d8; }
.formula-cell:empty::before,
.formula-cell[data-placeholder]:focus:empty::before {
  content: attr(data-placeholder);
  color: #c4c4c7;
  font-family: 'Courier New', monospace;
  font-size: 0.74rem;
  pointer-events: none;
}
.formula-cell sup { font-size: 0.65em; vertical-align: super; line-height: 0; }
.formula-cell sub { font-size: 0.65em; vertical-align: sub;   line-height: 0; }

/* Stacked fraction: numerator over denominator with a rule line */
.frac {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  vertical-align: middle;
  font-size: 0.85em;
  line-height: 1.2;
  margin: 0 2px;
}
.frac > span:first-child {
  border-bottom: 1px solid currentColor;
  padding: 0 3px 1px;
  text-align: center;
}
.frac > span:last-child {
  padding: 1px 3px 0;
  text-align: center;
}
.fp-eq   { font-style: normal; }
.fp-unit {
  font-style: italic;
  font-size: 0.82em;
  color: #6b7280;
  margin-left: 0.2em;
}

.formula-result {
  font-family: 'Courier New', monospace;
  font-size: 0.74rem;
  color: #059669;
  white-space: nowrap;
  min-width: 56px;
  text-align: right;
}
.formula-sep {
  font-family: 'Courier New', monospace;
  font-size: 0.74rem;
  color: #6b7280;
  flex-shrink: 0;
  -webkit-user-select: none;
  user-select: none;
}
.result-unit {
  font-style: italic;
  font-size: 0.85em;
  opacity: 0.75;
  margin-left: 0.15em;
}
.formula-fn {
  color: #7c3aed;
  font-style: italic;
  font-size: 0.7rem;
}
.formula-error {
  color: #ef4444;
  cursor: help;
  font-size: 0.7rem;
}
.formula-inactive {
  color: #d1d5db;
  font-style: italic;
}
.formula-cond-true  { color: #059669; font-size: 0.72rem; }
.formula-cond-false { color: #9ca3af; font-size: 0.72rem; }
.formula-loop-count { color: #3b82f6; font-size: 0.72rem; }

/* ── Control-flow rows ──────────────────────────────────────────────────── */
.formula-row--control {
  align-items: center;
  background: #f9fafb;
  border-radius: 3px;
  margin-top: 1px;
  min-height: calc(1.2rem + 3px);
}
.formula-row--inactive > .formula-expr-side > .formula-cell {
  opacity: 0.4;
}

/* Keyword badge (if / elseif / else / end / for) */
.formula-keyword {
  display: inline-block;
  font-family: 'Courier New', monospace;
  font-size: 0.72rem;
  font-weight: 700;
  padding: 1px 6px;
  border-radius: 3px;
  margin-right: 4px;
  white-space: nowrap;
  flex-shrink: 0;
  -webkit-user-select: none;
  user-select: none;
}
.formula-keyword--if,
.formula-keyword--elseif { background: #dbeafe; color: #1d4ed8; }
.formula-keyword--else   { background: #fef3c7; color: #92400e; }
.formula-keyword--end    { background: #f3f4f6; color: #6b7280; }
.formula-keyword--for    { background: #d1fae5; color: #065f46; }

/* Delete-variant toolbar button (× branch) */
.formula-branch-btn--del {
  border-color: #fecaca !important;
  background: #fef2f2 !important;
  color: #b91c1c !important;
}
.formula-branch-btn--del:hover:not(:disabled) { background: #fee2e2 !important; }


/* ── Plot block ─────────────────────────────────────────────────────────── */
.plot-block {
  min-width: 300px;
  padding: 0.5rem 0.5rem 0.4rem;
}

.plot-controls {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  margin-bottom: 0.4rem;
}

.plot-row {
  display: flex;
  align-items: center;
  gap: 0.3rem;
  flex-wrap: wrap;
}

.plot-label {
  font-size: 0.7rem;
  color: #6b7280;
  white-space: nowrap;
  -webkit-user-select: none;
  user-select: none;
}

.plot-input {
  font-family: 'Courier New', monospace;
  font-size: 0.75rem;
  border: 1px solid #d1d5db;
  border-radius: 3px;
  padding: 2px 5px;
  background: #f9fafb;
  color: inherit;
  min-width: 0;
}
.plot-input:focus { outline: 1px solid #3b82f6; border-color: #3b82f6; }

.plot-expr  { flex: 1; min-width: 8rem; }
.plot-xvar  { width: 2.2rem; text-align: center; }
.plot-range { width: 4.5rem; }

/* contentEditable math-preview cells inside plot blocks */
.plot-cell {
  outline: none;
  cursor: text;
  line-height: 1.5;
  font-family: 'Georgia', 'Times New Roman', serif;
  font-size: 0.8rem;
}
.plot-cell:focus {
  font-family: 'Courier New', monospace;
  font-size: 0.75rem;
}
.plot-cell:empty::before,
.plot-cell[data-placeholder]:focus:empty::before {
  content: attr(data-placeholder);
  color: #c4c4c7;
  font-family: 'Courier New', monospace;
  font-size: 0.74rem;
  pointer-events: none;
}
.plot-cell sup { font-size: 0.65em; vertical-align: super; line-height: 0; }
.plot-cell sub { font-size: 0.65em; vertical-align: sub;   line-height: 0; }

.plot-svg-wrap { line-height: 0; }
.plot-svg-wrap svg { max-width: 100%; height: auto; display: block; }

.plot-err {
  font-size: 0.7rem;
  color: #ef4444;
  margin-top: 0.2rem;
  min-height: 1em;
}

/* Plot right-click marker popup */
.plot-ctx-popup {
  position: fixed;
  z-index: 9999;
  background: #ffffff;
  border: 1px solid #e5e7eb;
  border-radius: 6px;
  padding: 6px 8px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.15);
  font-size: 0.78rem;
}
.plot-ctx-row {
  display: flex;
  align-items: center;
  gap: 5px;
}
.plot-ctx-label {
  color: #6b7280;
  flex-shrink: 0;
}
.plot-ctx-input {
  width: 6rem;
  font-size: 0.78rem;
  border: 1px solid #d1d5db;
  border-radius: 4px;
  padding: 2px 5px;
  outline: none;
}
.plot-ctx-input:focus { border-color: #2563eb; }
.plot-ctx-btn {
  font-size: 0.72rem;
  padding: 2px 7px;
  border: 1px solid #d1d5db;
  border-radius: 4px;
  background: #f9fafb;
  cursor: pointer;
  white-space: nowrap;
}
.plot-ctx-btn:hover { background: #f3f4f6; }
.plot-ctx-btn-primary {
  background: #2563eb;
  border-color: #2563eb;
  color: #fff;
}
.plot-ctx-btn-primary:hover { background: #1d4ed8; }


.formula-add-btn,
.formula-del-row {
  border: none;
  background: none;
  cursor: pointer;
  font-size: 0.7rem;
  padding: 1px 4px;
  border-radius: 2px;
  color: #9ca3af;
  line-height: 1;
  flex-shrink: 0;
}
.formula-add-btn:hover { background: #f0fdf4; color: #059669; }
.formula-del-row:hover { color: #ef4444; }


.module-item.custom { background: #eff6ff; }
.module-item.custom:hover { background: #dbeafe; }

/* Custom Tools heading with inline Import button */
h2.custom-tools-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 1rem;
}

.import-tools-btn {
  font-size: 0.6rem;
  font-family: inherit;
  padding: 2px 6px;
  border: 1px solid #d1d5db;
  border-radius: 3px;
  background: none;
  cursor: pointer;
  color: #6b7280;
  white-space: nowrap;
}
.import-tools-btn:hover { border-color: #3b82f6; color: #2563eb; background: #eff6ff; }

/* Import tools modal */
.import-modal-overlay {
  position: fixed;
  inset: 0;
  background: rgb(0 0 0 / 0.45);
  z-index: 20000;
  display: flex;
  align-items: center;
  justify-content: center;
}

.import-modal {
  background: #ffffff;
  border-radius: 0.5rem;
  box-shadow: 0 20px 40px rgb(0 0 0 / 0.25);
  padding: 1.25rem 1.5rem;
  min-width: 260px;
  max-width: 360px;
  width: 90vw;
}

.import-modal h3 {
  margin: 0 0 0.25rem;
  font-size: 0.95rem;
  font-weight: 700;
}

.import-modal-sub {
  margin: 0 0 0.75rem;
  font-size: 0.75rem;
  color: #6b7280;
}

.import-modal-list {
  max-height: 240px;
  overflow-y: auto;
  border: 1px solid #e4e4e7;
  border-radius: 0.25rem;
  padding: 0.25rem 0;
  margin-bottom: 0.75rem;
}

.import-tool-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.3rem 0.6rem;
  cursor: pointer;
  font-size: 0.8rem;
}
.import-tool-row:hover { background: #f4f4f5; }
.import-tool-row input[type="checkbox"] { flex-shrink: 0; cursor: pointer; }
.import-tool-row input[type="checkbox"]:disabled { cursor: default; }

.import-tool-exists {
  font-size: 0.68rem;
  color: #9ca3af;
  margin-left: auto;
  white-space: nowrap;
}

.import-modal-btns {
  display: flex;
  gap: 0.5rem;
  justify-content: flex-end;
}

.import-modal-btns button {
  font-family: inherit;
  font-size: 0.78rem;
  padding: 0.3rem 0.75rem;
  border-radius: 0.25rem;
  border: 1px solid #d1d5db;
  background: #f9fafb;
  cursor: pointer;
}
.import-modal-btns button:hover { background: #f3f4f6; }

.import-confirm-btn {
  background: #2563eb !important;
  border-color: #1d4ed8 !important;
  color: #ffffff !important;
}
.import-confirm-btn:hover { background: #1d4ed8 !important; }

/* ctx-menu: Save as Tool is not red */
#ctx-menu .ctx-save-btn {
  color: #b45309;
}
#ctx-menu .ctx-save-btn:hover {
  background: #fffbeb;
  color: #92400e;
}

.mod-delete {
  border: none;
  background: none;
  cursor: pointer;
  font-size: 0.75rem;
  color: #9ca3af;
  padding: 0 2px;
  line-height: 1;
  margin-left: auto;
  flex-shrink: 0;
}
.mod-delete:hover { color: #ef4444; }



/* Sidebar module items */
.module-item {
  display: flex;
  align-items: center;
  padding: 0.5rem;
  margin-bottom: 0.5rem;
  background: #f3f4f6;
  border-radius: 0.25rem;
  cursor: grab;
  transition: transform 150ms cubic-bezier(0.4, 0, 0.2, 1);
}

.module-item:active {
  transform: scale(0.95);
}

.module-item.placing {
  background: #eff6ff;
  outline: 1px solid #3b82f6;
  color: #2563eb;
}

.module-item span + span {
  margin-left: 0.5rem;
  font-size: 0.875rem;
}

/* Print */
@page {
  margin: 0;
  size: letter portrait;
}

@media print {
  body {
    overflow: visible;
    background: white;
  }

  #sidebar-left {
    display: none;
  }

  main {
    overflow: visible;
    padding: 0;
    background: white;
  }

  #app {
    display: block;
    height: auto;
    width: auto;
  }

  main {
    position: static;
  }

  #canvas {
    /* JS beforeprint handler converts inline px to in; this is a fallback */
    margin: 0 !important;
    padding: 0 !important;
    box-shadow: none !important;
    background-color: white !important;
    overflow: hidden;
  }

  #margin-guide,
  .page-guide {
    border: 1px solid #64748b;
    z-index: 99999;
    pointer-events: none;
    background-color: transparent !important;
    background-image: none !important;
  }

  .block {
    box-shadow: none;
    border-color: transparent;
    background: white !important;
  }

  .block.selected {
    box-shadow: none;
    border-color: transparent;
  }
  #selection-band { display: none !important; }
  #grid-cursor    { display: none !important; }
  .page-sep       { display: none !important; }
  .page-num       { display: block !important; }

  /* Hide empty placeholder text so it doesn't appear in print/PDF */
  .formula-desc-cell:empty::before,
  .formula-ref-cell:empty::before,
  [contenteditable][data-placeholder]:empty::before { content: none !important; }
}


/* ── Figure block ─────────────────────────────────────────────────────────── */
.figure-block {
  padding: 0;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-width: 80px;
  min-height: 60px;
  box-sizing: border-box;
  position: relative;
}

.figure-label {
  font-size: 0.7rem;
  font-weight: 600;
  color: #6b7280;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 3px 6px 2px;
  border-bottom: 1px solid #e4e4e7;
  flex-shrink: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.figure-img-wrap {
  flex: 1 1 0;
  min-height: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  background: #f9fafb;
  cursor: default;
}

.figure-img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
  pointer-events: none;
}

.figure-placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  color: #9ca3af;
  font-size: 0.75rem;
  text-align: center;
  cursor: pointer;
  padding: 0.5rem;
  box-sizing: border-box;
  -webkit-user-select: none;
  user-select: none;
}
.figure-placeholder:hover { color: #6b7280; background: #f3f4f6; }

.figure-caption {
  font-size: 0.75rem;
  color: #374151;
  text-align: center;
  padding: 3px 6px 4px;
  border-top: 1px solid #e4e4e7;
  outline: none;
  flex-shrink: 0;
  min-height: 1.2rem;
  white-space: pre-wrap;
}
.figure-caption:empty::before {
  content: attr(data-placeholder);
  color: #d1d5db;
  pointer-events: none;
}

/* SE corner resize handle */
.figure-resize-handle {
  position: absolute;
  bottom: 0;
  right: 0;
  width: 44px;
  height: 44px;
  cursor: se-resize;
  z-index: 3;
  touch-action: none;
}
.figure-resize-handle::after {
  content: '';
  position: absolute;
  bottom: 2px;
  right: 2px;
  width: 6px;
  height: 6px;
  border-right: 2px solid #94a3b8;
  border-bottom: 2px solid #94a3b8;
  opacity: 0;
  transition: opacity 150ms;
}
.figure-block:hover .figure-resize-handle::after,
.figure-block.selected .figure-resize-handle::after {
  opacity: 1;
}

@media print {
  .figure-resize-handle { display: none !important; }
  .figure-placeholder    { display: none !important; }
}


/* ── Section block ─────────────────────────────────────────────────────────── */
.section-block {
  /* Translucent so the page engineering grid shows through */
  background: rgba(241, 245, 249, 0.12) !important;
  border: 1px solid #cbd5e1;
  border-left: 4px solid var(--section-color, #3b82f6);
  box-shadow: none;
  box-sizing: border-box;
  min-width: 0;
  min-height: 80px;
  /* Section sits behind its absolutely-positioned child blocks */
  z-index: 0;
  padding: 0;
  cursor: default;
}
/* Children need higher z-index so they appear above the section background */
.section-content > .block { z-index: 1; }

.section-header {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0 0.5rem;
  height: 20px;
  box-sizing: border-box;
  border-bottom: 1px solid #e2e8f0;
  cursor: grab;
  background: rgba(255,255,255,0.55);
  -webkit-user-select: none;
  user-select: none;
  overflow: hidden;
}
.section-header:active { cursor: grabbing; }

.section-toggle {
  border: none;
  background: none;
  cursor: pointer;
  font-size: 0.65rem;
  color: #64748b;
  padding: 0 2px;
  line-height: 1;
  flex-shrink: 0;
}
.section-toggle:hover { color: #1d4ed8; }

.section-title {
  font-size: 0.8rem;
  font-weight: 700;
  font-family: 'Courier New', monospace;
  color: #1e293b;
  outline: none;
  flex: 1;
  min-width: 4rem;
  border-bottom: 1px solid transparent;
}
.section-title:focus { border-bottom-color: #3b82f6; }
.section-title:empty::before { content: attr(data-placeholder); color: #94a3b8; font-style: italic; font-weight: 400; }

.section-summary {
  padding: 0 0.6rem;
  height: 20px;
  box-sizing: border-box;
  display: flex;
  align-items: center;
  font-size: 0.7rem;
  font-family: 'Courier New', monospace;
  color: #000000;
  font-weight: 700;
  background: rgba(255,255,255,0.4);
  border-bottom: 1px solid #e2e8f0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.section-summary-empty { color: #94a3b8; font-style: italic; font-weight: 400; }
.section-cmp-pass { color: #16a34a; font-weight: 600; }
.section-cmp-fail { color: #dc2626; font-weight: 600; }

.section-content {
  position: relative;   /* children are absolute within this */
  min-height: 60px;
  background: rgba(248, 250, 252, 0.5);
}
.section-content.collapsed { display: none; }

/* When collapsed, let the block shrink to header + summary height only */
.section-block:has(> .section-content.collapsed) { min-height: 0; }

/* Drop-target highlight when dragging a non-section block over an open section */
.section-block.section-drop-target {
  background: rgba(219, 234, 254, 0.35) !important;
  border-color: #3b82f6;
  box-shadow: 0 0 0 2px #93c5fd;
}

/* Pull-down resize handle at the bottom of a section */
.section-resize-handle {
  height: 44px;
  cursor: ns-resize;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  background: transparent;
  touch-action: none;
}
.section-resize-handle::after {
  content: '';
  width: 40px;
  height: 3px;
  background: #94a3b8;
  border-radius: 2px;
  opacity: 0;
  transition: opacity 150ms;
}
.section-block:hover .section-resize-handle::after,
.section-block.selected .section-resize-handle::after {
  opacity: 1;
}

/* ── Touch-device resize handle enhancements ─────────────────────────────── */
/* (hover: none) + (pointer: coarse) = touch screen, not mouse/trackpad       */
@media (hover: none) and (pointer: coarse) {
  /* Always show indicators on selected blocks — hover doesn't exist on touch */
  .block.selected .text-resize-handle::after,
  .figure-block.selected .figure-resize-handle::after,
  .section-block.selected .section-resize-handle::after {
    opacity: 1;
  }

  /* Larger, more visible grip indicators on touch */
  .text-resize-handle::after {
    width: 5px;
    height: 44px;
    background: #94a3b8;
  }
  .figure-resize-handle::after {
    width: 14px;
    height: 14px;
    border-right-width: 3px;
    border-bottom-width: 3px;
    bottom: 6px;
    right: 6px;
  }
  .section-resize-handle::after {
    width: 64px;
    height: 5px;
  }

  /* Engaged state — lights up the moment a finger lands on the handle */
  .text-resize-handle.handle-active::after {
    background: #3b82f6;
    width: 6px;
    height: 52px;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.25);
    border-radius: 3px;
  }
  .figure-resize-handle.handle-active::after {
    border-color: #3b82f6;
    border-right-width: 4px;
    border-bottom-width: 4px;
    width: 18px;
    height: 18px;
    box-shadow: 2px 2px 0 2px rgba(59, 130, 246, 0.2);
  }
  .section-resize-handle.handle-active::after {
    background: #3b82f6;
    height: 6px;
    width: 80px;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.25);
    border-radius: 3px;
  }
}

@media print {
  .section-block {
    background: white !important;
    border-left-color: #94a3b8 !important;
    box-shadow: none;
  }
  .section-summary { background: #f8fafc !important; }
  .section-content { background: transparent !important; }
  .section-resize-handle { display: none !important; }
}

/* ── Title block ─────────────────────────────────────────────────────────── */
.title-block {
  padding: 0 !important;
  cursor: default !important;
  border: 1px solid #94a3b8;
  background: #ffffff !important;
  box-shadow: none;
  overflow: hidden;
}

.title-block-table {
  width: 100%;
  border-collapse: collapse;
  table-layout: fixed;
  font-family: system-ui, sans-serif;
  /* Fixed total height: 4 rows × 28px = 112px; rows never grow beyond this */
  height: 112px;
}

.title-block-table tr {
  height: 28px;
  max-height: 28px;
  overflow: hidden;
}

/* Outer border matches the block border — cells use inner borders only */
.title-block-table td {
  border: 1px solid #94a3b8;
  vertical-align: middle;
}

/* Logo cell — left column, rowspan 4 */
.tb-logo {
  width: 160px;
  min-width: 160px;
  max-width: 160px;
  overflow: hidden;
  vertical-align: middle !important;
  cursor: pointer;
  position: relative;
  border-right: 2px solid #475569 !important;
}

.tb-logo-img {
  display: block;
  width: 100%;
  max-height: 112px;  /* total title block height — never taller */
  height: auto;
  object-fit: contain;
  object-fit: contain;
  padding: 4px;
}

.tb-logo-ph {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  min-height: 60px;
  gap: 4px;
  color: #94a3b8;
  font-size: 0.65rem;
  text-align: center;
  padding: 4px;
  -webkit-user-select: none;
  user-select: none;
}

.tb-logo-ph-icon {
  font-size: 1.4rem;
  line-height: 1;
}

.tb-label {
  font-size: 0.58rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: #64748b;
  padding: 4px 5px;
  line-height: 1;
  -webkit-user-select: none;
  user-select: none;
  flex-shrink: 0;
}

.tb-value {
  outline: none;
  cursor: text;
  font-size: 0.8rem;
  font-family: system-ui, sans-serif;
  color: #1e293b;
  padding: 4px 5px;
  line-height: 1.4;
  white-space: pre-wrap;
  word-break: break-word;
  min-height: 1.2em;
}

.tb-value:focus {
  background: rgba(59, 130, 246, 0.05);
}

.tb-value:empty::before {
  content: attr(data-placeholder);
  color: #cbd5e1;
  pointer-events: none;
}

/* Narrow cells (By, Sheet No., Date, Job No.) vs wide cells (Project, Subject) */
.tb-wide   { width: auto; }
.tb-narrow { width: 90px; min-width: 70px; max-width: 110px; }
.tb-blank     { background: transparent; }
.tb-sheet-num { cursor: default; color: #475569; font-family: ui-monospace, monospace; font-size: 0.75rem; text-align: center; -webkit-user-select: none; user-select: none; }

/* Row separator inside the data area */
.title-block-table tr:first-child td,
.title-block-table tr:last-child  td {
  border-top: 1px solid #94a3b8;
  border-bottom: 1px solid #94a3b8;
}

/* Thicker top border — engineering style */
.title-block-table {
  border-top: 2px solid #475569;
  border-bottom: 2px solid #475569;
}


@media print {
  .title-block            { background: white !important; border-color: #64748b; }
  .title-block-table td   { border-color: #64748b; }
  .title-block-table      { border-top-color: #1e293b; border-bottom-color: #1e293b; }
  .tb-logo                { border-right-color: #1e293b !important; }
  .tb-value:empty::before { content: none !important; }
}

.sidebar-license {
  display: block;
  font-size: 10px;
  color: #94a3b8;
  text-decoration: none;
  text-align: center;
  padding: 2px 8px 8px;
  line-height: 1.4;
}

.sidebar-license:hover {
  text-decoration: underline;
}