:root {
  --border: #d0d5dd;
  --header-bg: #f4f6f8;
  --header-fg: #6b7280;
  --accent: #2563eb;
  --accent-bg: #dbe7ff;
  --active-bg: #ffffff;
  --cell-fg: #1a1a1a;
  --label-fg: #444;          /* toolbar field labels, and anything that must read as one */
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  margin: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
  padding: 20px;
  background: #fafbfc;
  color: #1a1a1a;
  overflow: hidden;
}

#app {
  display: flex;
  flex-direction: column;
  height: 100%;
  gap: 14px;
}

.app-header { flex: none; }

.app-header .controls-row {
  margin-top: 0;
  align-items: center; /* .controls-row defaults to flex-end for label+input toolbar fields; the header just has a heading + buttons */
}
.app-header .teal-button-link {
  margin-top: 0;
  margin-bottom: 0;
}

.app-toolbar {
  flex: none;
  display: flex;
  align-items: center;
  gap: 5px;
}

.primary-btn {
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 6px;
  padding: 8px 16px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
}
.primary-btn:hover { background: #1d4ed8; }

.controls-row {
	margin-top: 20px;
	display: flex;
	gap: 20px;
	align-items: flex-end;
	flex-wrap: wrap;
}
.field label {
	display: block;
	font-size: 13px;
	color: var(--label-fg);
	margin-bottom: 4px;
}
.field input, .field select {
	padding: 5px 8px;
	font-size: 14px;
	border: 1px solid #bbb;
	border-radius: 4px;
}

.app-main {
  flex: 1;
  display: flex;
  gap: 16px;
  min-height: 0; /* required for flex children to shrink instead of overflowing */
}

.panel {
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
}

/* 1 : 1 : 2 across the row. This said `flex: 3` until 2026-09-05 and was dead
   the whole time: every .panel-grid section carried an inline `style="flex: 1"`
   that won. The inline styles are gone and the value moved here unchanged, so
   the desktop layout is identical - but it can now be overridden below 900px,
   which an inline style could not be without !important. */
.panel-grid { flex: 1; }
.panel-chart { flex: 2; }

.panel-ad {
  flex: 0 0 160px;
  max-width: 160px;
}

.app-footer-ad {
  flex: none;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 4px 0;
}

.ad-slot-banner {
  width: 728px;
  height: 90px;
  max-width: 100%; /* graceful shrink on narrow viewports */
  border: 1px dashed var(--border); /* remove once ads confirmed rendering */
  border-radius: 4px;
  overflow: hidden;
}

.ad-slot {
	min-height: 250px; /* reserves space for a standard rectangle unit before load */
	border: 1px dashed var(--border); /* optional: visualize the reserved slot pre-approval */
	border-radius: 6px;
}

.panel-body {
  flex: 1;
  min-height: 0;
}

/* ---- Grid root ---- */
.gt-root {
  border: 0px solid var(--border);
  border-radius: 8px;
  background: #fafbfc;
  overflow: hidden;
  user-select: none;
}

.gt-scroll {
  position: relative;
  overflow: auto;
  width: 100%;
}

.gt-sizer {
  position: relative;
}

.gt-canvas {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  pointer-events: none; /* re-enabled on children */
}

.gt-canvas > * { pointer-events: auto; }

.gt-corner {
  position: absolute;
  top: 0; left: 0;
  background: var(--header-bg);
  border-right: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  z-index: 4;
}

.gt-colheader, .gt-rowheader, .gt-cells {
  position: absolute;
  top: 0; left: 0;
  width: 100%;
  height: 100%;
}

.gt-colheader { z-index: 3; pointer-events: none; }
.gt-rowheader { z-index: 3; pointer-events: none; }
.gt-cells { z-index: 1; }

.gt-header-cell { pointer-events: auto; }

.gt-header-cell {
  position: absolute;
  background: var(--header-bg);
  color: var(--header-fg);
  font-size: 12px;
  font-weight: 600;
  border-right: 1px solid var(--border);
  border-left: 1px solid var(--border);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  padding: 0 5px;
  overflow: hidden;
  white-space: nowrap;
}

.gt-header-cell.rownum { justify-content: center; padding: 0; }

.gt-col-resizer, .gt-row-resizer {
  position: absolute;
  z-index: 5;
  background: transparent;
}
.gt-col-resizer {
  top: 0; right: -3px; width: 6px; height: 100%;
  cursor: col-resize;
}
.gt-row-resizer {
  left: 0; bottom: -3px; height: 6px; width: 100%;
  cursor: row-resize;
}
.gt-col-resizer:hover, .gt-row-resizer:hover { background: var(--accent); opacity: 0.5; }

.gt-cell {
  position: absolute;
  background: white;
  color: var(--cell-fg);
  font-size: 13px;
  border-right: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding: 5px 7px;
  overflow: hidden;
  white-space: pre;
  text-overflow: ellipsis;
  cursor: cell;
}

.gt-cell.selected { background: var(--accent-bg); }
.gt-cell.active {
  background: var(--active-bg);
  box-shadow: inset 0 0 0 2px var(--accent);
  z-index: 2;
}
.gt-cell.editing {
  outline: none;
  cursor: text;
  white-space: pre-wrap;
  overflow: visible;
}

/* Add a global state modification flag to root */
.gt-root.gt-readonly .gt-cell {
  cursor: not-allowed; /* Shows block symbol on hover */
}

.gt-root.gt-readonly .gt-cell.selected {
  background: #f2f4f7; /* Muted slate background instead of vibrant blue */
}

.gt-hidden-input {
  position: fixed;
  top: -1000px;
  left: -1000px;
  width: 1px;
  height: 1px;
  opacity: 0;
  border: none;
  padding: 0;
}

/* ---- Context menu ---- */
.gt-context-menu {
  position: fixed;
  background: white;
  border: 1px solid var(--border);
  border-radius: 6px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.12);
  padding: 4px;
  z-index: 1000;
  min-width: 170px;
  font-size: 13px;
}
.gt-context-menu ul { list-style: none; margin: 0; padding: 0; }
.gt-context-menu li {
  padding: 7px 10px;
  border-radius: 4px;
  cursor: pointer;
  color: #1a1a1a;
}
.gt-context-menu li:hover { background: var(--header-bg); }
.gt-context-menu li.danger { color: #dc2626; }
.gt-context-menu li.sep {
  height: 1px;
  margin: 4px 2px;
  padding: 0;
  background: var(--border);
  cursor: default;
}

/* ---- Chart ---- */
.ct-root {
  position: relative;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: white;
  padding: 12px;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-height: 0;
}

.ct-canvas {
  display: block;
  width: 100%;
  flex: 1;
  min-height: 0;
}

.ct-tooltip {
  position: absolute;
  pointer-events: none;
  background: #1a1a1a;
  color: white;
  font-size: 11px;
  line-height: 1.4;
  padding: 6px 8px;
  border-radius: 5px;
  white-space: nowrap;
  transform: translateY(-100%);
  z-index: 10;
}

.ct-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 8px;
  padding-left: 4px;
}

.ct-legend-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: #374151;
}

.ct-legend-swatch {
  width: 10px;
  height: 10px;
  border-radius: 2px;
  display: inline-block;
}

.ct-context-menu {
  position: absolute;
  background: #ffffff;
  border: 1px solid #d0d5dd;
  border-radius: 6px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  padding: 4px 0;
  min-width: 120px;
  z-index: 9999;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 12px;
  display: none;
}
.ct-menu-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 12px;
  cursor: pointer;
  color: #374151;
  user-select: none;
}
.ct-menu-item:hover {
  background-color: #f3f4f6;
}
.ct-menu-checkbox {
  width: 12px;
  height: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
}
.ct-menu-separator {
  height: 1px;
  background-color: #e5e7eb;
  margin: 4px 0;
}
.ct-legend-break {
	flex-basis: 100%;
	height: 0;
}
.custom-link {
  display: inline-block;
  color: #00bfa5;          
  text-decoration: none;   
  font-weight: bold;       
  transition: color 0.2s ease, transform 0.2s ease;;
}
.custom-link:hover {
  color: #008b78;	
  text-decoration: none;  
  transform: scale(1.05);
}
.teal-button-link {
  display: inline-block;         
  background-color: #21c2b5; 
  color: #ffffff;                
  text-decoration: none;         
  font-weight: normal;
  padding: 5px 10px;            
  border-radius: 6px;            
  margin: 25px -5px !important;
  
  transition: background-color 0.2s ease, transform 0.2s ease; 
}
.teal-button-link:hover {
  background-color: #00bfa5;
  color: #ffffff;
  text-decoration: none;

  transform: scale(1.02);
}

/* ---- Blog / article pages (e.g. interpolate_blog.html) ---- */
body.blog-page { overflow: auto; } /* articles run taller than the viewport; calculator pages keep overflow:hidden */

/* header shares the post's max-width so both start at the same left edge */
body.blog-page .app-header {
  max-width: 720px;
  /* centred with .post below, so header and article share one left edge.
     width:100% is required: auto margins on a flex item cancel the default
     stretch, and the header would otherwise shrink to fit its buttons and
     centre at the wrong width. */
  width: 100%;
  margin-left: auto;
  margin-right: auto;
}

.post {
  max-width: 720px;
  /* The COLUMN is centred in the viewport. Text inside stays left-aligned -
     no text-align here, and never add one: a centred paragraph is unreadable
     at this measure. */
  width: 100%;
  margin-left: auto;
  margin-right: auto;
  padding-bottom: 60px;
}
.post h1 { margin-bottom: 4px; }
.post .subtitle { color: var(--header-fg); font-size: 15px; margin-bottom: 28px; }
.post h2 { margin-top: 36px; font-size: 20px; }
.post p, .post li {
  line-height: 1.65;
  font-size: 15px;
  color: var(--header-fg); /* soft grey body text, matches the calculator's label/header grey */
}
.post code {
  background: var(--header-bg);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1px 5px;
  font-size: 13px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
}
.post pre {
  background: #1a1a1a;
  color: #e5e7eb;
  border-radius: 8px;
  padding: 16px;
  overflow-x: auto;
  font-size: 13px;
  line-height: 1.5;
}
.post pre code { background: none; border: none; padding: 0; color: inherit; }
.post .note {
  border-left: 3px solid var(--accent);
  background: var(--accent-bg);
  padding: 10px 14px;
  border-radius: 0 6px 6px 0;
  font-size: 14px;
}

/* ---- Home / topic index (index.html) ---- */
/* Shares the article max-width so home and blog line up at the same left edge. */
body.home-page { overflow: auto; }
/* Home is the same centred 720px column as a blog page. width:100% is required
   on every one of these: auto margins cancel a flex item's default stretch, and
   the block would otherwise shrink to its content and centre at its own width,
   off the column's left edge. */
body.home-page .app-header {
  max-width: 720px;
  width: 100%;
  margin-left: auto;
  margin-right: auto;
}

.topic-list {
  max-width: 720px;
  width: 100%;
  margin-left: auto;
  margin-right: auto;
  padding-bottom: 40px;
}

/* One topic = one compact row: name, level buttons, toggle. Detail hides until asked. */
.topic-item { border-bottom: 1px solid var(--border); }
.topic-item:first-child { border-top: 1px solid var(--border); }

.topic-row {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  padding: 10px 4px;
}
.topic-name {
  font-weight: 700;
  font-size: 15px;
  color: var(--cell-fg);
  margin-right: 4px; /* buttons sit just after the title, not pushed to the edge */
}
/* base .teal-button-link carries `margin: 25px -5px !important` for the blog header;
   inside these compact rows the negative margin eats the flex gap, so cancel it. */
.topic-row .teal-button-link {
  font-size: 13px;
  margin: 0 !important;
}

/* bare caret - no chrome, the glyph itself is the affordance */
.topic-toggle {
  flex: none;
  width: 24px;
  height: 24px;
  padding: 0;
  line-height: 1;
  font-size: 18px;
  font-weight: 700;
  color: var(--header-fg);
  background: none;
  border: none;
  cursor: pointer;
  transition: color 0.15s ease;
}
.topic-toggle:hover { color: var(--accent); }
.topic-toggle[aria-expanded="true"] { color: var(--accent); }

.topic-detail {
  padding: 0 4px 12px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--header-fg);
  max-width: 640px;
}
.topic-detail .topic-meta {
  margin: 6px 0 0;
  font-size: 11px;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

/* de-emphasized dev links, below the real content */
.dev-section {
  max-width: 720px;
  width: 100%;
  margin-left: auto;
  margin-right: auto;
  margin-top: 24px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}
.dev-section h3 {
  margin: 0 0 10px;
  font-size: 12px;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--header-fg);
  font-weight: 600;
}
.topic-links { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }
.dev-section .topic-links a {
  font-size: 13px;
  opacity: 0.75;
  margin: 0 !important; /* same negative-margin cancel as .topic-row */
}

/* Panel action buttons — the import / export controls in a panel heading.
   Moved here from interpolation_style.css on 2026-09-04, alongside the code
   that draws them (dev_basic/csv.ts). */
.panel-actions {
  display: inline-flex;
  gap: 6px;
  margin-left: 12px;
  vertical-align: middle;
}

/* .primary-btn's outline sibling: same shape, no fill, so "interpolate" stays
   the one filled button on the page and these read as secondary. */
.ghost-btn {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 10px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
}
.ghost-btn:hover {
  border-color: var(--accent);
  background: var(--accent-bg);
}

/* Format fallback beside the export button, revealed only where the save dialog
   cannot offer a type dropdown. Same border, radius and size as .ghost-btn so
   the pair reads as one control. */
.ghost-select {
  color: var(--accent);
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 6px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
}

/* ==========================================================================
   Narrow screens
   ==========================================================================
   PC and large tablet are the reference layout and everything above this line
   is theirs. This block is purely additive: it changes no existing rule, so a
   desktop viewport never reaches any of it and cannot regress.

   The calculator is a three-panel row pinned to the viewport, which is exactly
   what a phone cannot show. Below the breakpoint it becomes a scrolling column.
   The grids still scroll sideways inside their own panels - that is what a
   spreadsheet does on a phone - but the PAGE must never scroll sideways. */
/* ---- hint row: the how-to manual and the request box, side by side ---- */
/* Both are one-line <details> summaries, so a row costs #app one line instead
   of two. It owns the positioning context for BOTH floating bodies: anchored to
   their own <details> instead, the request panel would open at its summary's x
   and run off the right of a narrow window. */
.panel-hints {
  flex: none;
  position: relative;
  display: flex;
  align-items: center;
  gap: 18px;
  flex-wrap: wrap;
}
.panel-hints .how-to {
  /* The ROW is the positioning context for both floating bodies. */
  position: static;
}
.panel-hints .how-to,
.panel-hints .feedback {
  /* A flex item defaults to min-width:auto, which refuses to shrink below its
     content. The how-to summary is a long sentence, so without this the row
     pushes past a narrow viewport and the page scrolls sideways. */
  min-width: 0;
  max-width: 100%;
}
/* fit-content is right when the summary owns its line. Inside the row it must
   be free to wrap instead of setting the row's width. */
.panel-hints > details > summary {
  width: auto;
}

/* ---- "Send a request" panel: on both calculators ---- */
/* Private by design: nothing typed here is ever rendered back, so there is no
   comment list to style and no moderation state to show. The panel is a
   <details> like the how-to one, so the form exists in the HTML before any
   script runs.

   Not on the blog. The user's call: a request belongs where someone is using
   the tool, not where they are reading about it. */
.feedback {
  flex: none;
}
.feedback > summary {
  cursor: pointer;
  width: fit-content;
  padding: 2px 4px;
  font-size: 13px;
  line-height: 1.5;
  color: var(--label-fg);
}
.feedback > summary:hover,
.feedback[open] > summary {
  color: var(--accent);
}

.feedback-body {
  /* Floats over the grids, exactly like .how-to-body and for the same reason:
     #app is a column flex at height 100%, so a panel in normal flow would take
     its height from them. .panel-hints is the positioning context, so this
     anchors to the row's left edge rather than to its own summary - anchored to
     the summary it would open at that x and run off a narrow window. */
  position: absolute;
  top: calc(100% + 8px);
  left: 0;
  z-index: 30;
  width: min(760px, calc(100vw - 60px));
  max-height: min(60vh, 520px);
  overflow-y: auto;
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.12);
  padding: 14px 18px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--active-bg);
  font-size: 13px;
  line-height: 1.6;
  color: var(--header-fg);
}

.feedback-intro {
  margin: 0 0 12px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
  color: var(--cell-fg);
}

.feedback-form label {
  display: block;
  margin-bottom: 4px;
  color: var(--label-fg);
}
.feedback-form textarea,
.feedback-form input[type="text"] {
  width: 100%;
  padding: 8px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--active-bg);
  color: var(--cell-fg);
  font-family: inherit;
  font-size: 13px;
}
.feedback-form textarea {
  min-height: 96px;
  resize: vertical;
}
.feedback-field + .feedback-field { margin-top: 10px; }

.feedback-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 12px;
}
#feedbackStatus { color: var(--header-fg); }
#feedbackStatus.is-error { color: #b42318; }

/* The honeypot. Off-screen, NOT display:none - a bot that skips hidden inputs
   also skips display:none, and this field only works if it gets filled. Never
   reachable by Tab and never announced: tabindex="-1" and aria-hidden are on
   the input itself. */
.feedback-hp {
  position: absolute;
  left: -9999px;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

@media (max-width: 900px) {

  /* The rule that made the calculator unreachable rather than merely cramped:
     height:100% plus body{overflow:hidden} means a narrow viewport shows the
     header and nothing else, with no way to scroll to the panels. */
  html, body {
    height: auto;
    min-height: 100%;
  }

  body {
    overflow: auto;
    /* 40px of horizontal padding is a tenth of a 390px screen. */
    padding: 12px;
  }

  #app {
    height: auto;
    gap: 10px;
  }

  /* Title and nav buttons stop competing for one line. */
  .app-header {
    flex-wrap: wrap;
    gap: 8px;
  }
  .app-header h1 {
    font-size: 20px;
    line-height: 1.25;
  }

  .app-main {
    flex-direction: column;
  }

  /* flex: 3 / flex: 2 divided the horizontal axis. Once the axis is vertical
     inside an auto-height column those ratios mean nothing, so each panel takes
     an explicit height instead.

     This is also the trap in stacking: calc-page.ts builds both grids with
     viewportHeight: '100%', and 100% of an auto height is zero. Without a real
     height here the grids render empty. */
  .panel-grid,
  .panel-chart {
    flex: none;
  }
  .panel-grid { height: 55vh; min-height: 300px; }
  .panel-chart { height: 40vh; min-height: 240px; }

  /* Ads are a desktop-only column; a 160px rail on a phone is pure cost. */
  .panel-ad { display: none; }
}