:root {
      /* dark scale — anchored to #192831 */
      --bg:        #192831;
      --surface:   #1f3040;
      --surface-2: #263848;
      --surface-3: #2d4154;
      --border:    #334b61;
      --border-2:  #3f5c74;
      --text:      #E9E3DA;
      --text-2:    #8aaec2;  /* was #7a96a8 — bumped for 4.5:1 on surface */
      --text-3:    #6e9ab2;  /* was #445e6e — bumped for 4.5:1 on bg */
      --accent:     #6366f1;
      --accent-dim: #3730a3;
      --accent-text:#a5b4fc;
      --green: #4ade80;      /* was #22c55e — brighter for contrast on dark surface */
      --mono: 'JetBrains Mono', 'Fira Code', ui-monospace, monospace;
      --sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
      --serif: 'Aleo', Georgia, serif;
      --r: 8px;
      --r-sm: 4px;
      --r-lg: 12px;
    }

    /* ── Light mode overrides ── */
    body.light-mode {
      /* light scale — anchored to #E9E3DA */
      --bg:        #E9E3DA;
      --surface:   #F4EEE6;
      --surface-2: #EDE7DE;
      --surface-3: #E1DBD1;
      --border:    #CCC5BB;
      --border-2:  #B3ACA1;
      --text:      #192831;
      --text-2:    #4d6070;
      --text-3:    #5c7d90;  /* was #8ea0ae — darkened for 4.5:1 on bg */
      --accent:     #4f46e5;
      --accent-dim: #dde3ff;
      --accent-text:#4338ca;
      --green: #166534;  /* was #16a34a — darkened for 3:1 on light surface */
    }

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

    .sr-only {
      position: absolute;
      width: 1px; height: 1px;
      padding: 0; margin: -1px;
      overflow: hidden;
      clip: rect(0,0,0,0);
      white-space: nowrap;
      border: 0;
    }

    body {
      font-family: var(--sans);
      background: var(--bg);
      color: var(--text);
      min-height: 100vh;
      -webkit-font-smoothing: antialiased;
      transition: background 0.2s, color 0.2s;
    }

    /* ── Theme toggle (segmented) ── */
    .theme-seg {
      display: flex;
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--r);
      padding: 3px;
      gap: 2px;
      flex-shrink: 0;
    }
    .theme-opt {
      background: none;
      border: 1px solid transparent;
      border-radius: calc(var(--r) - 2px);
      color: var(--text-2);
      font-size: 15px;
      width: 32px;
      height: 28px;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      transition: all 0.12s;
    }
    .theme-opt:hover { color: var(--text); }
    .theme-opt.active {
      background: var(--surface-2);
      border-color: var(--border-2);
      color: var(--text);
    }

    /* ── Layout shell ── */
    header, .hero, .output-section {
      padding-left:  clamp(20px, 5vw, 64px);
      padding-right: clamp(20px, 5vw, 64px);
    }

    /* ── Header ── */
    header {
      padding-top: 52px;
      padding-bottom: 40px;
      border-bottom: 1px solid var(--border);
      display: flex;
      align-items: flex-end;
      justify-content: space-between;
      gap: 16px;
    }

    .header-text h1 {
      font-family: var(--serif);
      font-size: 2rem;
      font-weight: 600;
      letter-spacing: -0.01em;
      margin-bottom: 6px;
    }

    .header-text p {
      font-size: 13px;
      color: var(--text-2);
      max-width: 440px;
      line-height: 1.65;
    }

    /* ── Hero / Tool ── */
    .hero {
      padding-top: 48px;
      padding-bottom: 40px;
      border-bottom: 1px solid var(--border);
    }

    .section-label {
      font-size: 10px;
      font-weight: 600;
      letter-spacing: 0.12em;
      text-transform: uppercase;
      color: var(--text-3);
      margin-bottom: 20px;
    }

    .pattern-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      flex-wrap: wrap;
      gap: 8px;
      margin-bottom: 20px;
    }
    .pattern-header .section-label { margin-bottom: 0; }

    .pattern-controls {
      display: flex;
      align-items: center;
      gap: 12px;
    }

    /* Share button */
    .share-btn {
      display: flex;
      align-items: center;
      gap: 5px;
      background: transparent;
      border: 1px solid var(--border);
      border-radius: var(--r-sm);
      color: var(--text-3);
      font-family: var(--sans);
      font-size: 11px;
      font-weight: 500;
      padding: 4px 9px;
      cursor: pointer;
      transition: all 0.12s;
      white-space: nowrap;
    }
    .share-btn:hover { color: var(--text-2); border-color: var(--border-2); }
    .share-btn.copied { color: var(--accent-text); border-color: var(--accent); }

    /* Pattern builder row */
    .pattern-row {
      display: flex;
      align-items: center;
      gap: 4px;
      flex-wrap: wrap;
      min-height: 44px;
      margin-bottom: 20px;
    }

    .seg-sep {
      font-family: var(--mono);
      font-size: 15px;
      color: var(--text-3);
      padding: 0 2px;
      pointer-events: none;
      user-select: none;
    }

    .segment-card {
      display: flex;
      align-items: center;
      gap: 5px;
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--r);
      padding: 7px 8px 7px 6px;
      cursor: grab;
      transition: border-color 0.12s, background 0.12s, opacity 0.12s, box-shadow 0.12s;
      user-select: none;
      position: relative;
    }

    .segment-card:hover { border-color: var(--border-2); }
    .segment-card:active { cursor: grabbing; }

    .segment-card.is-dragging {
      opacity: 0.35;
    }

    .segment-card.seg-ghost {
      opacity: 0.18;
      pointer-events: none;
    }

    .segment-card.seg-connected {
      outline: 1.5px solid color-mix(in srgb, var(--accent) 40%, transparent);
      outline-offset: 1px;
    }

    .seg-sep {
      transition: opacity 0.18s;
    }

    .seg-sep.seg-ghost {
      opacity: 0.12;
    }

    .segment-card.drop-before::before {
      content: '';
      position: absolute;
      left: -5px;
      top: 0; bottom: 0;
      width: 2px;
      background: var(--accent);
      border-radius: 2px;
    }

    .segment-card.drop-after::after {
      content: '';
      position: absolute;
      right: -5px;
      top: 0; bottom: 0;
      width: 2px;
      background: var(--accent);
      border-radius: 2px;
    }

    .drag-handle {
      color: var(--text-3);
      font-size: 11px;
      cursor: grab;
      letter-spacing: -0.5px;
      line-height: 1;
      margin-right: 0;   /* spacing now handled by seg-rule */
    }

    /* Thin vertical rule separating drag affordance from the editable value */
    .seg-rule {
      width: 1px;
      align-self: stretch;
      background: var(--border);
      margin: 2px 6px;
      flex-shrink: 0;
      border-radius: 1px;
    }

    .seg-select-wrap {
      display: inline-flex;
      align-items: center;
      flex: none;
      position: relative;
      margin-right: 10px;
    }

    .seg-chevron {
      position: absolute;
      right: 0;
      top: 50%;
      transform: translateY(-50%);
      color: var(--text-3);
      pointer-events: none;
      user-select: none;
      display: inline-flex;
      align-items: center;
    }

    .seg-select {
      background: transparent;
      border: none;
      color: var(--text);
      font-family: var(--sans);
      font-size: 12px;
      font-weight: 500;
      cursor: pointer;
      outline: none;
      padding: 0 14px 0 0;
      appearance: none;
      -webkit-appearance: none;
    }

    .seg-select option {
      background: var(--surface-2);
      color: var(--text);
    }

    .seg-remove {
      background: none;
      border: none;
      color: var(--text-3);
      cursor: pointer;
      font-size: 15px;
      padding: 0;
      line-height: 1;
      transition: color 0.12s;
      margin-left: 1px;
    }

    .seg-remove:hover { color: var(--text-2); }

    .add-segment {
      display: flex;
      align-items: center;
      gap: 5px;
      background: transparent;
      border: 1px dashed var(--border);
      border-radius: var(--r);
      padding: 7px 12px;
      color: var(--text-3);
      font-family: var(--sans);
      font-size: 12px;
      font-weight: 500;
      cursor: pointer;
      transition: border-color 0.12s, color 0.12s;
    }

    .add-segment:hover {
      border-color: var(--accent);
      color: var(--accent-text);
    }

    /* Preview bar */
    .preview-bars {
      display: flex;
      flex-direction: column;
      gap: 6px;
      margin-bottom: 18px;
    }

    .preview-bar {
      display: flex;
      align-items: center;
      flex-wrap: wrap;
      gap: 8px 14px;
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--r);
      padding: 11px 16px;
      transition: border-color 0.15s;
    }
    .preview-bar:hover {
      border-color: var(--border-2);
    }

    .preview-label {
      font-size: 10px;
      font-weight: 600;
      letter-spacing: 0.1em;
      text-transform: uppercase;
      color: var(--text-3);
      white-space: nowrap;
      flex-shrink: 0;
      min-width: 70px;
    }

    .preview-name {
      font-family: var(--mono);
      font-size: 13px;
      color: var(--text);
      word-break: break-all;
      display: flex;
      align-items: baseline;
      flex-wrap: wrap;
      gap: 0;
      min-width: 0;   /* allow shrink inside flex bar */
      flex: 1;
    }

    .prev-sep {
      color: var(--text-3);
      padding: 0 0px;
      user-select: none;
    }

    .prev-tok {
      position: relative;
      display: inline-flex;
      align-items: baseline;
    }

    .prev-tok-label {
      font-family: var(--mono);
      font-size: 13px;
      color: var(--text);
      line-height: 1.5;
    }

    /* Only interactive tokens get the hover treatment */
    .prev-tok-interactive { cursor: pointer; }

    .prev-tok-interactive .prev-tok-label {
      border-bottom: 1px dashed transparent;
      transition: color 0.12s, border-color 0.12s;
    }

    .prev-tok-interactive:hover .prev-tok-label {
      color: var(--accent-text);
      border-bottom-color: var(--accent);
    }


    /* ── Gap system ──────────────────────────────────────────────────────────
       Inner gap: CSS grid stacking — sep and + occupy the same cell.
       No absolute positioning, so nothing overflows the container.
       Edge gap: fixed-size square that contains the + button cleanly.
    ─────────────────────────────────────────────────────────────────────── */

    /* Inner gap: grid stack so + replaces sep in-place, always square */
    .prev-gap {
      display: inline-grid;
      place-items: center;
      aspect-ratio: 1;
      min-height: 1.15em;      /* anchors height → aspect-ratio derives equal width */
      vertical-align: middle;
    }
    /* Both children share the single grid cell */
    .prev-gap > .prev-sep,
    .prev-gap > .prev-insert { grid-area: 1 / 1; }

    .prev-gap > .prev-sep { transition: opacity 0.12s; }
    .prev-gap:hover > .prev-sep,
    .prev-gap:focus-within > .prev-sep { opacity: 0; pointer-events: none; }

    /* Edge gap: same square grid approach, no separator to stack */
    .prev-gap-edge {
      display: inline-grid;
      place-items: center;
      aspect-ratio: 1;
      min-height: 1.15em;
      vertical-align: middle;
      position: relative;
    }

    /* ── + button (shared base) ── */
    .prev-insert {
      background: var(--surface-3);
      border: 1px solid var(--border);
      border-radius: 3px;
      color: var(--text-3);
      font-size: 11px;
      line-height: 1;
      cursor: pointer;
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.15s, color 0.12s, border-color 0.12s;
      white-space: nowrap;
      z-index: 10;
      position: relative;      /* ::after tooltip relative to the button */
    }

    /* Inner gap button: fill the cell so it's same width as sep */
    .prev-gap > .prev-insert {
      align-self: stretch;
      justify-self: stretch;
      display: flex;
      align-items: center;
      justify-content: center;
      padding: 0 3px;
    }

    /* Edge gap button: contained within the square */
    .prev-gap-edge > .prev-insert {
      padding: 2px 4px;
    }

    /* Reveal rules */
    .prev-gap:hover > .prev-insert,
    .prev-gap:focus-within > .prev-insert { opacity: 1; pointer-events: auto; }

    .preview-bar:hover .prev-gap-edge > .prev-insert { opacity: 0.4; pointer-events: auto; }
    .preview-bar:hover .prev-gap-edge:hover > .prev-insert,
    .prev-gap-edge:focus-within > .prev-insert { opacity: 1; pointer-events: auto; }

    .prev-insert:hover,
    .prev-insert:focus { color: var(--accent-text); border-color: var(--accent); background: var(--surface-2); outline: none; }

    /* Tooltip */
    .prev-insert::after {
      content: attr(data-adds);
      position: absolute;
      top: calc(100% + 6px);
      left: 50%;
      transform: translateX(-50%);
      background: var(--surface-2);
      border: 1px solid var(--border-2);
      border-radius: var(--r-sm);
      color: var(--text-2);
      font-family: var(--mono);
      font-size: 10px;
      padding: 3px 8px;
      white-space: nowrap;
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.12s;
      z-index: 20;
    }
    .prev-insert:hover::after,
    .prev-insert:focus::after { opacity: 1; }

    /* Remove row inside popover */
    .popover-divider {
      width: 100%;
      height: 1px;
      background: var(--border);
      margin: 6px 0 2px;
    }
    .popover-remove {
      color: #f87171 !important;
      border-color: transparent !important;
      background: transparent !important;
      width: 100%;
      text-align: left;
      font-size: 11px;
      display: flex;
      align-items: center;
      gap: 5px;
    }
    .popover-remove:hover {
      color: #ef4444 !important;
      border-color: transparent !important;
      background: rgba(239, 68, 68, 0.08) !important;
    }

    /* Popover */
    .token-popover {
      position: fixed;
      z-index: 200;
      background: var(--surface-2);
      border: 1px solid var(--border-2);
      border-radius: var(--r);
      padding: 8px;
      display: flex;
      flex-wrap: wrap;
      gap: 4px;
      max-width: 280px;
      box-shadow: 0 8px 32px rgba(0,0,0,0.5);
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.1s, transform 0.1s;
      transform: translateY(4px);
    }

    .token-popover.visible {
      opacity: 1;
      pointer-events: auto;
      transform: translateY(0);
    }

    .popover-opt {
      background: transparent;
      border: 1px solid var(--border);
      border-radius: var(--r-sm);
      color: var(--text-2);
      font-family: var(--mono);
      font-size: 11px;
      padding: 3px 9px;
      cursor: pointer;
      transition: all 0.1s;
      line-height: 1.5;
    }

    .popover-opt:hover {
      border-color: var(--accent);
      color: var(--accent-text);
      background: var(--surface-3);
    }

    .popover-opt.is-current {
      border-color: var(--accent);
      color: var(--accent-text);
      background: var(--accent-dim);
    }

    /* Controls row */
    .controls-row {
      display: flex;
      align-items: center;
      flex-wrap: wrap;
      gap: 12px 24px;
    }

    .undo-btn {
      display: flex;
      align-items: center;
      gap: 5px;
      background: transparent;
      border: 1px solid var(--border);
      border-radius: var(--r-sm);
      color: var(--text-3);
      font-family: var(--sans);
      font-size: 11px;
      font-weight: 500;
      padding: 5px 10px;
      cursor: pointer;
      transition: all 0.12s;
      letter-spacing: 0.02em;
    }
    .undo-btn:hover:not(:disabled) { color: var(--text-2); border-color: var(--border-2); }
    .undo-btn:disabled { opacity: 0.3; cursor: default; }

    .ctrl-label {
      font-size: 10px;
      font-weight: 600;
      letter-spacing: 0.1em;
      text-transform: uppercase;
      color: var(--text-3);
    }

    .sep-group {
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .sep-btns { display: flex; gap: 3px; }

    .sep-btn {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--r-sm);
      color: var(--text-2);
      font-family: var(--mono);
      font-size: 13px;
      padding: 3px 10px;
      cursor: pointer;
      transition: all 0.12s;
      line-height: 1.5;
    }

    .sep-btn:hover { border-color: var(--border-2); color: var(--text); }
    .sep-btn.active { border-color: var(--accent); color: var(--accent-text); background: var(--surface-2); }

    /* ── Output section ── */
    .output-section {
      padding-top: 48px;
      padding-bottom: 64px;
    }

    .scaffold-desc {
      font-size: 12px;
      color: var(--text-2);
      max-width: 520px;
      line-height: 1.6;
    }

    /* ── AI prompt card ── */
    .ai-prompt-card {
      margin-top: 16px;
      border: 1px solid var(--border);
      border-radius: var(--r);
      padding: 14px 16px;
      background: var(--surface);
    }

    .ai-prompt-card-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 16px;
    }

    .ai-prompt-title {
      display: block;
      font-size: 12px;
      font-weight: 600;
      color: var(--text);
      margin-bottom: 2px;
    }

    .ai-prompt-sub {
      font-size: 11px;
      color: var(--text-2);
    }

    .ai-prompt-copy-btn {
      display: flex;
      align-items: center;
      gap: 6px;
      flex-shrink: 0;
      background: var(--accent);
      border: none;
      border-radius: var(--r-sm);
      color: #fff;
      font-family: var(--sans);
      font-size: 11px;
      font-weight: 500;
      padding: 6px 12px;
      cursor: pointer;
      transition: opacity 0.12s;
    }
    .ai-prompt-copy-btn:hover { opacity: 0.88; }
    .ai-prompt-copy-btn.copied { background: var(--green); }

    /* ── Footer ── */
    .site-footer {
      padding: 24px clamp(20px, 5vw, 64px);
      border-top: 1px solid var(--border);
      display: flex;
      align-items: center;
      gap: 16px;
    }
    .site-footer-divider {
      width: 1px;
      height: 12px;
      background: var(--border-2);
      flex-shrink: 0;
    }
    .site-footer-copy {
      font-size: 12px;
      color: var(--text-3);
    }
    .site-footer-copy a {
      color: var(--text-2);
      text-decoration: none;
    }
    .site-footer-copy a:hover { color: var(--text); }
    .site-footer-icons {
      display: flex;
      align-items: center;
      gap: 14px;
    }
    .site-footer-icons a {
      color: var(--text-3);
      display: flex;
      align-items: center;
      transition: color 0.12s;
    }
    .site-footer-icons a:hover { color: var(--text); }
    .site-footer-icons svg { width: 16px; height: 16px; fill: currentColor; }

    .output-header {
      display: flex;
      align-items: center;
      justify-content: space-between;
      flex-wrap: wrap;
      gap: 12px;
      margin-bottom: 28px;
    }

    /* Segmented control */
    .segmented {
      display: flex;
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--r);
      padding: 3px;
      gap: 2px;
    }

    .seg-btn {
      background: none;
      border: 1px solid transparent;
      border-radius: calc(var(--r) - 2px);
      color: var(--text-2);
      font-family: var(--sans);
      font-size: 12px;
      font-weight: 500;
      padding: 5px 14px;
      cursor: pointer;
      transition: all 0.12s;
    }

    .seg-btn:hover { color: var(--text); }
    .seg-btn.active { background: var(--surface-2); border-color: var(--border-2); color: var(--text); }

    /* Tier tabs */
    .tier-tabs {
      display: flex;
      flex-wrap: wrap;
      border-bottom: 1px solid var(--border);
      margin-bottom: 24px;
      gap: 0;
    }

    .tier-tab {
      background: none;
      border: none;
      border-bottom: 2px solid transparent;
      color: var(--text-2);
      font-family: var(--sans);
      font-size: 12px;
      font-weight: 500;
      padding: 10px 18px;
      cursor: pointer;
      transition: all 0.12s;
      margin-bottom: -1px;
      letter-spacing: 0.01em;
    }

    .tier-tab:hover { color: var(--text); }
    .tier-tab.active { color: var(--accent-text); border-bottom-color: var(--accent); }

    /* Code block */
    .code-wrapper { position: relative; }

    .copy-btn {
      position: absolute;
      top: 12px;
      right: 12px;
      background: var(--surface-2);
      border: 1px solid var(--border-2);
      border-radius: var(--r-sm);
      color: var(--text-2);
      font-family: var(--sans);
      font-size: 11px;
      font-weight: 500;
      padding: 5px 11px;
      cursor: pointer;
      transition: all 0.12s;
      letter-spacing: 0.02em;
      z-index: 1;
    }

    .copy-btn:hover { color: var(--text); border-color: var(--border-2); }
    .copy-btn.copied { color: var(--green); border-color: var(--green); }

    pre {
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--r-lg);
      padding: 20px;
      overflow: auto;
      font-family: var(--mono);
      font-size: 12px;
      line-height: 1.75;
      height: calc(100vh - 480px);
      min-height: 320px;
      max-width: 100%;
      tab-size: 2;
    }

    /* JSON syntax colors — dark mode */
    .jk { color: #93c5fd; }
    .js { color: #86efac; }
    .jn { color: #fca5a5; }
    .jref { color: #c4b5fd; }
    .jp { color: var(--text-2); }
    .jt { color: var(--text-3); }

    /* JSON syntax colors — light mode */
    body.light-mode .jk   { color: #2563eb; }
    body.light-mode .js   { color: #16a34a; }
    body.light-mode .jn   { color: #dc2626; }
    body.light-mode .jref { color: #7c3aed; }

    /* Collapsible JSON tree */
    pre { white-space: normal; }
    .jline {
      display: flex;
      align-items: center;
      line-height: 1.75;
      min-height: 1.75em;
    }
    .jgutter {
      width: 20px;
      flex-shrink: 0;
      align-self: stretch;
      display: flex;
      align-items: center;
      justify-content: center;
      border-right: 1px solid color-mix(in srgb, var(--border) 55%, transparent);
    }
    .jtext { white-space: nowrap; }
    .jtoggle {
      background: none;
      border: none;
      color: var(--text-3);
      opacity: 0.25;
      cursor: pointer;
      padding: 0;
      width: 16px;
      height: 16px;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 2px;
      transition: opacity 0.15s, color 0.15s;
      flex-shrink: 0;
    }
    .jtoggle:hover { opacity: 1; color: var(--accent); }
    .jchildren { display: block; }
    .jcollapsed { color: var(--text-3); }

    /* ── Mobile wall ── */
    .mobile-wall {
      display: none;
      position: fixed;
      inset: 0;
      z-index: 9999;
      background: var(--bg);
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 20px;
      padding: 40px 32px;
      text-align: center;
    }

    .mobile-wall-icon {
      color: var(--text-3);
      opacity: 0.5;
    }

    .mobile-wall h1 {
      font-family: var(--serif);
      font-size: 1.4rem;
      font-weight: 600;
      color: var(--text);
    }

    .mobile-wall p {
      font-size: 14px;
      color: var(--text-2);
      max-width: 280px;
      line-height: 1.6;
    }

    @media (max-width: 768px) {
      .mobile-wall { display: flex; }
      body > *:not(.mobile-wall) { display: none !important; }
    }