:root {
      --bg:        #eef2f7;
      --surface:   #ffffff;
      --border:    #c8d6e8;
      --text:      #1a2540;
      --muted:     #3a527a;
      --accent:    #2563eb;
      --accent-dim:#bfcfef;
      --mono:      ui-monospace, 'Cascadia Code', 'Menlo', 'Consolas', monospace;
      --serif:     'Iowan Old Style', 'Palatino Linotype', 'Georgia', serif;
      --radius:    4px;
      --trans:     200ms ease;
    }
    
    a { color: var(--accent); text-decoration: none; }
    a:hover { text-decoration: underline; color: var(--accent-muted); }

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

    html, body {
      min-height: 100%;
      background: var(--bg);
      color: var(--text);
      font-family: var(--serif);
      font-size: 17px;
      line-height: 1.65;
    }

    /* ── Layout shell ── */
    #app {
      min-height: 100vh;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 2rem 1rem;
    }

    .card {
      hyphens: auto; 
      background: var(--surface);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      width: 100%;
      max-width: 640px;
      padding: 2.5rem 3rem;
      box-shadow: 0 2px 16px rgba(37,99,235,.08);
    }
    
    ul {
      background: #f5f5f5;
      padding: 1em 0em 1em 3em;
      border-radius: var(--radius)
    }

    /* ── Typography ── */
    .label {
      font-family: var(--mono);
      font-size: .7rem;
      letter-spacing: .12em;
      text-transform: uppercase;
      color: var(--muted);
      margin-bottom: .75rem;
    }

    h1 {
      font-size: 1.6rem;
      font-weight: 600;
      line-height: 1.3;
      margin-bottom: .5rem;
    }

    h2 {
      font-size: 1.15rem;
      font-weight: 600;
      line-height: 1.4;
      margin-bottom: 1rem;
    }

    p { margin-bottom: .9rem; color: #1e3050; }
    p:last-child { margin-bottom: 0; }

    /* ── Progress bar ── */
    .progress-wrap {
      width: 100%;
      max-width: 640px;
      margin-bottom: .75rem;
    }
    .progress-meta {
      display: flex;
      justify-content: space-between;
      font-family: var(--mono);
      font-size: .68rem;
      color: var(--muted);
      margin-bottom: .3rem;
    }
    .progress-track {
      height: 3px;
      background: var(--border);
      border-radius: 2px;
      overflow: hidden;
    }
    .progress-fill {
      height: 100%;
      background: var(--accent);
      border-radius: 2px;
      transition: width .4s ease;
    }

    /* ── Privacy scroll box ── */
    .scroll-box {
      height: 280px;
      overflow-y: auto;
      border: 1px solid var(--border);
      border-radius: var(--radius);
      padding: 1.2rem 1.4rem;
      margin: 1.25rem 0;
      font-size: .95rem;
      line-height: 1.7;
      background: #f4f8ff;
      scroll-behavior: smooth;
    }
    .scroll-box::-webkit-scrollbar { width: 5px; }
    .scroll-box::-webkit-scrollbar-track { background: transparent; }
    .scroll-box::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

    .scroll-notice {
      font-family: var(--mono);
      font-size: .72rem;
      color: var(--accent);
      margin-top: .4rem;
      transition: opacity var(--trans);
    }
    .scroll-notice.hidden { opacity: 0; pointer-events: none; }

    /* ── Checkbox row ── */
    .check-row {
      display: flex;
      gap: .75rem;
      align-items: flex-start;
      margin-top: 1.25rem;
    }
    .check-row input[type="checkbox"] {
      width: 18px;
      height: 18px;
      margin-top: .22rem;
      accent-color: var(--accent);
      flex-shrink: 0;
      cursor: pointer;
    }
    .check-row label {
      font-size: .93rem;
      color: var(--muted);
      cursor: pointer;
      line-height: 1.5;
    }

    /* ── Buttons ── */
    .btn {
      font-family: var(--mono);
      font-size: .8rem;
      letter-spacing: .06em;
      text-transform: uppercase;
      padding: .65rem 1.8rem;
      border: 1px solid var(--text);
      background: var(--text);
      color: var(--surface);
      border-radius: var(--radius);
      cursor: pointer;
      transition: background var(--trans), color var(--trans), opacity var(--trans);
      margin-top: 1.5rem;
    }
    .btn:hover:not(:disabled) { background: var(--accent); border-color: var(--accent); }
    .btn:disabled { opacity: .35; cursor: not-allowed; }
    .btn.outline {
      background: transparent;
      color: var(--text);
    }
    .btn.outline:hover:not(:disabled) { background: var(--text); color: var(--surface); }

    /* ── Intro text ── */
    .intro-text {
      font-size: 1rem;
      line-height: 1.75;
      color: var(--text);
      white-space: pre-line;
    }
    .intro-counter {
      font-family: var(--mono);
      font-size: .7rem;
      color: var(--muted);
      margin-bottom: 1.25rem;
    }

    /* ── Rating screen ── */
    .question-wrap {
      margin: 1.5rem 0 2rem;
      text-align: center;
    }
    .question-text {
      font-size: 1.25rem;
      font-weight: 300;
      font-style: italic;
      line-height: 1.6;
      color: var(--text);
    }
    .question-word {
      font-style: normal;
      font-weight: 600;
      color: var(--accent);
      font-size: 1.4rem;
      display: inline-block;
      transition: opacity .18s ease;
    }

    /* ── Vertical scale ── */
    .scale-wrap {
      margin-top: 1.75rem;
    }
    .scale-options {
      display: flex;
      flex-direction: column;
    }
    .scale-option {
      display: flex;
      align-items: center;
      gap: .75rem;
      padding: .45rem .6rem;
      border-radius: var(--radius);
      cursor: pointer;
      transition: background var(--trans);
      user-select: none;
    }
    .scale-option:hover { background: #e8f0fb; }
    .scale-option:hover .scale-radio { border-color: var(--accent); }
    .scale-radio {
      width: 17px;
      height: 17px;
      border-radius: 50%;
      border: 1.5px solid var(--border);
      background: var(--surface);
      flex-shrink: 0;
      display: flex;
      align-items: center;
      justify-content: center;
      transition: border-color var(--trans);
    }
    .scale-radio::after {
      content: '';
      width: 8px;
      height: 8px;
      border-radius: 50%;
      background: var(--accent);
      opacity: 0;
      transition: opacity .12s ease;
    }
    .scale-option.selected .scale-radio { border-color: var(--accent); }
    .scale-option.selected .scale-radio::after { opacity: 1; }
    .scale-label { font-size: .98rem; color: var(--text); }
    .scale-divider {
      border: none;
      border-top: 1px solid var(--border);
      margin: .5rem .6rem;
    }
    .scale-option.extra .scale-label { color: var(--muted); font-style: italic; }

    /* ── Spinner / loader ── */
    .spinner-wrap {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 1.25rem;
    }
    .spinner {
      width: 36px;
      height: 36px;
      border: 2.5px solid var(--border);
      border-top-color: var(--accent);
      border-radius: 50%;
      animation: spin .8s linear infinite;
    }
    @keyframes spin { to { transform: rotate(360deg); } }
    .spinner-text {
      font-family: var(--mono);
      font-size: .75rem;
      color: var(--muted);
      letter-spacing: .08em;
    }

    /* ── Done screen ── */
    .done-icon {
      font-size: 2.5rem;
      margin-bottom: 1rem;
      display: block;
      text-align: center;
    }
    .done-code {
      font-family: var(--mono);
      font-size: .85rem;
      background: #eef4ff;
      border-radius: var(--radius);
      padding: .5rem 1rem;
      display: inline-block;
      color: var(--accent);
      letter-spacing: .05em;
      margin-top: .5rem;
    }

    /* ── Error ── */
    .error-box {
      background: #eef4ff;
      border: 1px solid var(--accent-dim);
      border-radius: var(--radius);
      padding: 1rem 1.25rem;
      font-size: .92rem;
      color: var(--accent);
      margin-top: 1rem;
    }

    /* ── Fade transition ── */
    .fade { animation: fadeIn .3s ease both; }
    @keyframes fadeIn { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }

    /* ── Responsive ── */
    @media (max-width: 520px) {
      .card { padding: 1.75rem 1.4rem; }
      .scale-label { font-size: .92rem; }
    }
    
    /* Two-column input layout */
    .text-fields-wrap {
      display: flex;
      gap: 1.25rem;
      margin: 1.5rem 0 0;
    }

    .text-field-col {
      flex: 1;
      display: flex;
      flex-direction: column;
      gap: .5rem;
    }

    .text-field-label {
      font-size: .85rem;
      font-weight: 600;
      color: var(--muted, #666);
      line-height: 1.3;
    }

    .text-field-input {
      width: 100%;
      box-sizing: border-box;
      padding: .6rem .75rem;
      border: 1.5px solid var(--border, #d0d0d0);
      border-radius: 6px;
      font-size: 1rem;
      font-family: inherit;
      background: var(--surface, #fff);
      color: var(--text, #111);
      transition: border-color .15s, box-shadow .15s;
      resize: vertical;
      min-height: 2.6rem;
    }

    .text-field-input:focus {
      outline: none;
      border-color: var(--accent, #4a6fa5);
      box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent, #4a6fa5) 18%, transparent);
    }

    .text-field-input:disabled {
      background: var(--surface-muted, #f3f3f3);
      color: var(--muted, #888);
      cursor: not-allowed;
    }

    /* Divider between fields and the "unknown" option */
    .text-unknown-divider {
      border: none;
      border-top: 1px solid var(--border, #d8d8d8);
      margin: 1.25rem 0 1rem;
    }

    /* Radio row for "unknown" */
    .text-unknown-row {
      display: flex;
      align-items: center;
      gap: .65rem;
      cursor: pointer;
      user-select: none;
    }

    .text-unknown-row input[type="checkbox"] {
      accent-color: var(--accent, #4a6fa5);
      width: 1.05rem;
      height: 1.05rem;
      flex-shrink: 0;
      cursor: pointer;
    }

    .text-unknown-row span {
      font-size: .9rem;
      color: var(--muted, #666);
    }

    /* Submit button – reuses existing .btn but scoped here for margin */
    .text-submit-btn {
      margin-top: 1.5rem;
      width: 100%;
    }
    
    .scale-option.selected .scale-radio { background: var(--accent); border-color: var(--accent); }
    .error-box { background: #2a1a1a; color: #f87171; border: 1px solid #f87171; }
    .done-icon { color: var(--accent); }
    .done-code { background: var(--surface2); border: 1px solid var(--border); }
    textarea.text-field-input { background: var(--surface2); border: 1px solid var(--border); color: var(--text); }
    textarea.text-field-input:focus { border-color: var(--accent); outline: none; }
    a { color: var(--accent); text-decoration: none; }
    a:hover { text-decoration: underline; color: var(--accent-h); }
    /* Example explanation box */
    .example-explanation {
      margin-top: 1.25rem;
      background: var(--surface2);
      border-left: 3px solid var(--accent);
      border-radius: 6px;
      padding: .85rem 1rem;
      font-size: .9rem;
      color: var(--muted);
    }
    .example-explanation-title {
      display: block;
      font-size: .75rem;
      font-weight: 600;
      letter-spacing: .06em;
      text-transform: uppercase;
      color: var(--accent);
      margin-bottom: .4rem;
    }
    .example-explanation p { margin: 0; line-height: 1.6; }

    /* ── Demographics form ── */
.demo-section {
      border-top: 1px solid var(--accent);
      padding: 1.25rem 0 .5rem;
      margin-bottom: .25rem;
    }
    .demo-section:first-of-type { border-top: none; }
    .demo-question {
      font-weight: 600;
      color: var(--text);
      margin-bottom: .75rem;
      line-height: 1.5;
    }
    .demo-sub-question {
      font-size: .9rem;
      color: var(--muted);
      margin-bottom: .5rem;
      margin-top: .25rem;
      line-height: 1.5;
    }
    .demo-radio-row {
      display: flex;
      align-items: center;
      gap: .6rem;
      padding: .35rem .5rem;
      border-radius: 6px;
      cursor: pointer;
      font-size: .92rem;
      color: var(--text);
      transition: background .15s;
      margin-bottom: .1rem;
    }
    .demo-radio-row:hover { background: var(--surface2); }
    .demo-radio-row input[type="radio"] { accent-color: var(--accent); flex-shrink: 0; }
    .demo-check-row {
      display: flex;
      align-items: center;
      gap: .6rem;
      padding: .3rem .5rem;
      font-size: .85rem;
      color: var(--muted);
      cursor: pointer;
      margin-top: .4rem;
    }
    .demo-check-row input[type="checkbox"] { accent-color: var(--accent); flex-shrink: 0; }
    .demo-inline-text {
      background: var(--surface2);
      border: 1px solid var(--border);
      border-radius: 5px;
      color: var(--text);
      padding: .25rem .5rem;
      font-size: .88rem;
      width: 12rem;
      transition: border-color .15s;
    }
    .demo-inline-text:focus { border-color: var(--accent); outline: none; }
    .demo-inline-text:disabled { opacity: .35; cursor: not-allowed; }
    .demo-number {
      background: var(--surface2);
      border: 1px solid var(--border);
      border-radius: 6px;
      color: var(--text);
      padding: .4rem .7rem;
      font-size: 1rem;
      width: 6rem;
    }
    .demo-number:focus { border-color: var(--accent); outline: none; }
    .demo-number:disabled { opacity: .35; }
    /* Frequency scale */
    .demo-freq-scale {
      display: flex;
      flex-wrap: wrap;
      gap: .4rem;
      margin-top: .5rem;
    }
    .demo-freq-option {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: .3rem;
      background: var(--surface2);
      border: 1px solid var(--border);
      border-radius: 8px;
      padding: .5rem .6rem;
      cursor: pointer;
      flex: 1;
      min-width: 80px;
      text-align: center;
      transition: border-color .15s, background .15s;
    }
    .demo-freq-option:hover { border-color: var(--accent); }
    .demo-freq-option input[type="radio"] { display: none; }
    .demo-freq-option:has(input:checked) {
      border-color: var(--accent);
      background: color-mix(in srgb, var(--accent) 15%, var(--surface2));
    }
    .demo-freq-num {
      font-size: 1.1rem;
      font-weight: 700;
      color: var(--accent);
    }
    .demo-freq-lbl {
      font-size: .72rem;
      color: var(--muted);
      line-height: 1.3;
    }
    /* Per-language frequency rows */
    .demo-lang-freq-row {
      margin-bottom: 1rem;
    }
    .demo-lang-name {
      display: inline-block;
      font-weight: 600;
      color: var(--accent);
      margin-bottom: .3rem;
      font-size: .9rem;
    }