:root {
    --bg:        #1a1a18;
    --bg2:       #222220;
    --bg3:       #2c2c29;
    --border:    #3a3a36;
    --border2:   #4a4a45;
    --amber:     #e8930a;
    --amber-d:   #c47a06;
    --amber-pale:#2e2410;
    --amber-glow:rgba(232,147,10,0.12);
    --white:     #f0ede6;
    --gray-100:  #d4d0c8;
    --gray-300:  #8a8880;
    --gray-500:  #5a5850;
    --green-acc: #4caf6e;
    --red-acc:   #e05a3a;
    --shadow:    0 4px 24px rgba(0,0,0,0.5);
    --shadow-lg: 0 8px 48px rgba(0,0,0,0.7);
  }

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

  body {
    font-family: 'Barlow', sans-serif;
    background: var(--bg);
    color: var(--white);
    min-height: 100vh;
    /* subtle grid texture */
    background-image:
      linear-gradient(rgba(255,255,255,0.015) 1px, transparent 1px),
      linear-gradient(90deg, rgba(255,255,255,0.015) 1px, transparent 1px);
    background-size: 40px 40px;
  }

  /* ── HEADER ── */
  header {
    background: var(--bg2);
    border-bottom: 3px solid var(--amber);
    padding: 0 2rem;
    height: 68px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 20px rgba(0,0,0,0.6);
  }

  .logo {
    font-family: 'Oswald', sans-serif;
    font-weight: 700;
    font-size: 1.6rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--white);
  }
  .logo span { color: var(--amber); }
  .logo-sub {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.7rem;
    letter-spacing: 0.18em;
    text-transform: uppercase;
    color: var(--gray-300);
    display: block;
    margin-top: -4px;
  }

  /* ── LAYOUT ── */
  .container {
    max-width: 1140px;
    margin: 0 auto;
    padding: 2.5rem 1.5rem;
  }

  .page-intro {
    margin-bottom: 2rem;
    border-left: 4px solid var(--amber);
    padding-left: 1.25rem;
  }
  .page-intro h1 {
    font-family: 'Oswald', sans-serif;
    font-weight: 700;
    font-size: 2rem;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    color: var(--white);
  }
  .page-intro p {
    color: var(--gray-300);
    font-size: 0.9rem;
    margin-top: 0.25rem;
    font-weight: 300;
  }

  /* ── NAV ── */
  .calc-nav {
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
    margin-bottom: 2rem;
    background: var(--bg2);
    border: 2px solid var(--border);
    border-radius: 4px;
    padding: 6px;
  }
  .calc-nav button {
    background: transparent;
    border: 2px solid transparent;
    border-radius: 3px;
    padding: 8px 16px;
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--gray-300);
    cursor: pointer;
    transition: all 0.15s;
    display: flex;
    align-items: center;
    gap: 6px;
    white-space: nowrap;
  }
  .calc-nav button:hover { color: var(--white); border-color: var(--border2); }
  .calc-nav button.active {
    background: var(--amber);
    color: #1a1a18;
    border-color: var(--amber);
  }
  .calc-nav button .nav-icon { font-size: 1rem; }

  /* ── CARD ── */
  .calc-card {
    background: var(--bg2);
    border: 2px solid var(--border);
    border-radius: 4px;
    overflow: hidden;
    display: none;
    animation: fadeUp 0.2s ease;
    box-shadow: var(--shadow);
  }
  .calc-card.active { display: block; }

  @keyframes fadeUp {
    from { opacity: 0; transform: translateY(8px); }
    to   { opacity: 1; transform: translateY(0); }
  }

  .calc-header {
    background: var(--bg3);
    border-bottom: 3px solid var(--amber);
    padding: 1.25rem 1.75rem;
    display: flex;
    align-items: center;
    gap: 1rem;
  }
  .calc-header-icon {
    font-size: 2rem;
    line-height: 1;
    filter: grayscale(0.2);
  }
  .calc-header h2 {
    font-family: 'Oswald', sans-serif;
    font-weight: 600;
    font-size: 1.35rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--white);
    margin-bottom: 0.2rem;
  }
  .calc-header p {
    color: var(--gray-300);
    font-size: 0.85rem;
    font-weight: 300;
  }

  /* ── BODY GRID ── */
  .calc-body {
    padding: 1.75rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
  }
  @media (max-width: 660px) {
    .calc-body { grid-template-columns: 1fr; padding: 1.25rem; }
  }

  .inputs-col, .result-col { display: flex; flex-direction: column; gap: 0.9rem; }

  /* ── FIELDS ── */
  .field { display: flex; flex-direction: column; gap: 5px; }
  .field label {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--gray-300);
  }
  .field-row { display: flex; gap: 6px; }
  .field-row input, .field-row select { flex: 1; }

  input[type="number"],
  input[type="text"],
  select {
    width: 100%;
    padding: 10px 12px;
    background: var(--bg3);
    border: 2px solid var(--border);
    border-radius: 3px;
    font-family: 'Barlow', sans-serif;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--white);
    outline: none;
    transition: border-color 0.15s;
    -moz-appearance: textfield;
  }
  input[type="number"]::-webkit-inner-spin-button { -webkit-appearance: none; }
  input:focus, select:focus { border-color: var(--amber); background: #28281f; }
  select { cursor: pointer; }
  select option { background: var(--bg3); color: var(--white); }

  .calc-btn {
    background: var(--amber);
    color: #1a1a18;
    border: none;
    border-radius: 3px;
    padding: 13px 28px;
    font-family: 'Oswald', sans-serif;
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    cursor: pointer;
    transition: background 0.15s, transform 0.1s;
    margin-top: 0.4rem;
    width: 100%;
  }
  .calc-btn:hover { background: #f5a020; }
  .calc-btn:active { transform: scale(0.98); background: var(--amber-d); }

  /* ── RESULT BOX ── */
  .result-box {
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: 3px;
    padding: 1.25rem;
    min-height: 180px;
    display: flex;
    flex-direction: column;
    gap: 0;
    justify-content: center;
    position: relative;
    overflow: hidden;
  }
  .result-box::before {
    content: '';
    position: absolute;
    top: 0; left: 0;
    width: 4px; height: 100%;
    background: var(--amber);
  }
  .result-box.has-result { justify-content: flex-start; }

  .result-placeholder {
    color: var(--gray-500);
    font-size: 0.88rem;
    text-align: center;
    font-style: italic;
    padding-left: 8px;
  }

  .result-item {
    display: flex;
    flex-direction: column;
    gap: 2px;
    padding: 8px 8px 8px 12px;
    border-bottom: 1px solid var(--border);
  }
  .result-item:last-child { border-bottom: none; }

  .result-label {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--amber);
  }
  .result-value {
    font-family: 'Oswald', sans-serif;
    font-size: 1.2rem;
    font-weight: 500;
    color: var(--white);
    letter-spacing: 0.02em;
  }
  .result-note {
    font-size: 0.78rem;
    color: var(--gray-300);
    margin-top: 0.5rem;
    background: var(--bg3);
    border: 1px solid var(--border);
    border-radius: 3px;
    padding: 8px 12px;
    line-height: 1.5;
  }

  /* ── SECTION LABELS ── */
  .section-label {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.16em;
    text-transform: uppercase;
    color: var(--amber);
    border-bottom: 1px solid var(--border);
    padding-bottom: 5px;
    display: flex;
    align-items: center;
    gap: 8px;
  }
  .section-optional {
    font-size: 0.68rem;
    font-weight: 400;
    text-transform: none;
    letter-spacing: 0;
    color: var(--gray-500);
    font-style: italic;
    font-family: 'Barlow', sans-serif;
  }

  /* ── AMORTIZATION TABLE ── */
  .amort-wrap { margin-top: 0.5rem; }
  .amort-title {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--amber);
    margin-bottom: 0.6rem;
  }
  .amort-scroll {
    max-height: 280px;
    overflow-y: auto;
    border: 2px solid var(--border);
    border-radius: 3px;
    scrollbar-width: thin;
    scrollbar-color: var(--amber) var(--bg3);
  }
  .amort-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.85rem;
  }
  .amort-table th {
    background: var(--bg3);
    padding: 9px 12px;
    text-align: left;
    font-family: 'Barlow Condensed', sans-serif;
    font-weight: 700;
    font-size: 0.72rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--amber);
    border-bottom: 2px solid var(--border);
    position: sticky;
    top: 0;
  }
  .amort-table td {
    padding: 7px 12px;
    border-bottom: 1px solid var(--border);
    color: var(--gray-100);
    font-family: 'Barlow', sans-serif;
    font-weight: 400;
  }
  .amort-table tr:last-child td { border-bottom: none; }
  .amort-table tr:hover td { background: var(--bg3); }

  /* ── AD UNITS ── */
  .ad-leaderboard-wrap {
    padding: 8px 0 4px;
    text-align: center;
    background: var(--bg2);
    border-bottom: 1px solid var(--border);
  }
  .ad-leaderboard-wrap .ad-label {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.65rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--gray-500);
    display: block;
    margin-bottom: 4px;
  }
  .ad-leaderboard-slot {
    display: inline-block;
    width: 728px;
    max-width: 100%;
    height: 90px;
    background: var(--bg3);
    border: 1px solid var(--border);
  }
  .ad-results-wrap {
    margin-top: 0.75rem;
    text-align: center;
  }
  .ad-results-wrap .ad-label {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.65rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--gray-500);
    display: block;
    margin-bottom: 4px;
  }
  .ad-results-slot {
    display: inline-block;
    width: 100%;
    max-width: 300px;
    height: 250px;
    background: var(--bg3);
    border: 1px solid var(--border);
  }

  /* ── FOOTER ── */
  footer {
    text-align: center;
    padding: 2rem;
    color: var(--gray-500);
    font-size: 0.78rem;
    font-family: 'Barlow', sans-serif;
    border-top: 1px solid var(--border);
    margin-top: 2rem;
  }

  /* ── PRIVACY POLICY ── */
  .privacy-toggle {
    background: none;
    border: none;
    color: var(--amber);
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.78rem;
    letter-spacing: 0.06em;
    cursor: pointer;
    padding: 0.25rem 0;
    margin-top: 0.5rem;
    text-decoration: underline;
    text-underline-offset: 3px;
    display: inline-block;
  }
  .privacy-toggle:hover { color: var(--white); }
  .privacy-section {
    display: none;
    text-align: left;
    max-width: 860px;
    margin: 1.5rem auto 0;
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 2rem 2.25rem;
    font-family: 'Barlow', sans-serif;
    font-size: 0.84rem;
    color: var(--gray-100);
    line-height: 1.75;
  }
  .privacy-section.open { display: block; }
  .privacy-section h2 {
    font-family: 'Oswald', sans-serif;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--white);
    letter-spacing: 0.08em;
    text-transform: uppercase;
    margin: 0 0 0.25rem;
  }
  .privacy-section h3 {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.86rem;
    font-weight: 600;
    color: var(--amber);
    letter-spacing: 0.1em;
    text-transform: uppercase;
    margin: 1.5rem 0 0.4rem;
    border-bottom: 1px solid var(--border);
    padding-bottom: 0.25rem;
  }
  .privacy-section p { margin: 0 0 0.65rem; color: var(--gray-100); }
  .privacy-section a { color: var(--amber); }
  .privacy-updated { font-size: 0.75rem; color: var(--gray-500); margin-bottom: 1.5rem !important; }

  /* ── CONTACT SECTION ── */
  .contact-section {
    max-width: 860px;
    margin: 2.5rem auto 0;
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 2rem 2.25rem;
  }
  .contact-section h2 {
    font-family: 'Oswald', sans-serif;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--white);
    letter-spacing: 0.08em;
    text-transform: uppercase;
    margin: 0 0 0.35rem;
  }
  .contact-section .contact-sub {
    font-family: 'Barlow', sans-serif;
    font-size: 0.82rem;
    color: var(--gray-300);
    margin-bottom: 1.5rem;
  }
  .contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.9rem;
  }
  .contact-grid .full { grid-column: 1 / -1; }
  .contact-field {
    display: flex;
    flex-direction: column;
    gap: 0.3rem;
  }
  .contact-field label {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--gray-300);
  }
  .contact-field input,
  .contact-field textarea,
  .contact-field select {
    background: var(--bg3);
    border: 1px solid var(--border2);
    border-radius: 3px;
    color: var(--white);
    font-family: 'Barlow', sans-serif;
    font-size: 0.88rem;
    padding: 0.55rem 0.75rem;
    width: 100%;
    box-sizing: border-box;
    transition: border-color 0.15s;
  }
  .contact-field input:focus,
  .contact-field textarea:focus {
    outline: none;
    border-color: var(--amber);
  }
  .contact-field textarea { resize: vertical; min-height: 120px; }
  .contact-submit {
    margin-top: 1.1rem;
    display: flex;
    align-items: center;
    gap: 1rem;
  }
  .contact-submit button {
    background: var(--amber);
    color: #111;
    border: none;
    border-radius: 3px;
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.88rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    padding: 0.6rem 1.75rem;
    cursor: pointer;
    transition: background 0.15s;
  }
  .contact-submit button:hover { background: var(--amber-d); }
  .contact-note {
    font-family: 'Barlow', sans-serif;
    font-size: 0.75rem;
    color: var(--gray-500);
  }
  @media (max-width: 580px) {
    .contact-grid { grid-template-columns: 1fr; }
    .contact-grid .full { grid-column: 1; }
  }

  /* ── APPLICATION RATE CALCULATOR ── */
/* ── PRODUCT INFO CARD (shown after selection) ── */
  .product-info-card {
    background: var(--bg);
    border: 1px solid var(--border2);
    border-left: 3px solid var(--amber);
    border-radius: 3px;
    padding: 10px 12px;
    display: none;
    flex-direction: column;
    gap: 6px;
  }
  .product-info-card.visible { display: flex; }
  .pic-name {
    font-family: 'Oswald', sans-serif;
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    color: var(--white);
  }
  .pic-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4px 12px;
  }
  .pic-item { display: flex; flex-direction: column; gap: 1px; }
  .pic-item-label {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.65rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--gray-500);
  }
  .pic-item-value {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--amber);
  }
  .pic-primary-badge {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.65rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: #1a1a18;
    background: var(--amber);
    border-radius: 2px;
    padding: 1px 5px;
    display: inline-block;
    margin-left: 5px;
  }

  /* ── PRESET RATE ROW ── */
  .preset-rate-row {
    display: flex;
    gap: 8px;
    align-items: center;
    display: none;
  }
  .preset-rate-row.visible { display: flex; }
  .preset-rate-row input { flex: 1; font-size: 0.9rem; padding: 9px 12px; }
  .preset-rate-unit {
    display: flex; align-items: center;
    padding: 0 10px;
    background: var(--bg3);
    border: 2px solid var(--border);
    border-radius: 3px;
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.8rem;
    font-weight: 600;
    letter-spacing: 0.06em;
    color: var(--amber);
    white-space: nowrap;
  }
  .preset-apply-btn {
    background: var(--amber);
    color: #1a1a18;
    border: none;
    border-radius: 3px;
    padding: 9px 16px;
    font-family: 'Oswald', sans-serif;
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    cursor: pointer;
    transition: background 0.15s;
    white-space: nowrap;
  }
  .preset-apply-btn:hover { background: #f5a020; }

  .preset-status {
    font-size: 0.73rem;
    padding: 6px 10px;
    border-radius: 3px;
    background: var(--bg3);
    border: 1px solid var(--border);
    line-height: 1.4;
    display: none;
  }
  .preset-status.ok    { border-color: var(--green-acc); color: var(--green-acc); }
  .preset-status.error { border-color: var(--red-acc);   color: #e07060; }

  /* ── VOLUME MODE DISPLAY ── */
  .vol-active-box {
    background: var(--bg3);
    border: 1px solid var(--border2);
    border-left: 3px solid var(--green-acc);
    border-radius: 3px;
    padding: 8px 12px;
    font-size: 0.78rem;
    color: var(--gray-300);
    line-height: 1.5;
    display: none;
  }
  .vol-active-box.visible { display: block; }
  .vol-active-box strong { color: var(--green-acc); }

  /* ── BUTTONS ── */
  .calc-btn { background: var(--amber); color: #1a1a18; border: none; border-radius: 3px; padding: 13px 28px; font-family: 'Oswald', sans-serif; font-size: 1rem; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; cursor: pointer; transition: background 0.15s, transform 0.1s; width: 100%; margin-top: 0.25rem; }
  .calc-btn:hover { background: #f5a020; }
  .calc-btn:active { transform: scale(0.98); background: var(--amber-d); }
  .reset-btn { background: transparent; color: var(--gray-300); border: 2px solid var(--border); border-radius: 3px; padding: 9px 28px; font-family: 'Oswald', sans-serif; font-size: 0.9rem; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; cursor: pointer; transition: all 0.15s; width: 100%; }
  .reset-btn:hover { color: var(--white); border-color: var(--border2); }

  /* ── RESULT BOX ── */
  .result-box { background: var(--bg); border: 2px solid var(--border); border-radius: 3px; padding: 1.25rem; min-height: 220px; display: flex; flex-direction: column; justify-content: center; position: relative; overflow: hidden; }
  .result-box::before { content: ''; position: absolute; top: 0; left: 0; width: 4px; height: 100%; background: var(--amber); }
  .result-box.has-result { justify-content: flex-start; }
  .result-placeholder { color: var(--gray-500); font-size: 0.88rem; text-align: center; font-style: italic; padding-left: 8px; }
  .pump-setting-display { display: flex; flex-direction: column; align-items: center; padding: 1.5rem 1rem 1.25rem; border-bottom: 1px solid var(--border); gap: 4px; }
  .pump-setting-label { font-family: 'Barlow Condensed', sans-serif; font-size: 0.72rem; font-weight: 700; letter-spacing: 0.18em; text-transform: uppercase; color: var(--amber); }
  .pump-setting-value { font-family: 'Oswald', sans-serif; font-size: 3.8rem; font-weight: 700; line-height: 1; color: var(--green-acc); }
  .pump-setting-value span { font-size: 2rem; font-weight: 500; color: var(--green-acc); }
  .pump-setting-value.over { color: var(--red-acc); }
  .pump-setting-value.over span { color: var(--red-acc); }
  .pump-setting-sub { font-family: 'Barlow', sans-serif; font-size: 0.8rem; color: var(--gray-300); font-weight: 300; margin-top: 2px; }
  .gauge-wrap { padding: 10px 12px 12px; border-bottom: 1px solid var(--border); }
  .gauge-track { height: 10px; background: var(--bg3); border-radius: 5px; overflow: hidden; border: 1px solid var(--border); }
  .gauge-fill { height: 100%; border-radius: 5px; transition: width 0.5s cubic-bezier(0.25,1,0.5,1); background: var(--amber); }
  .gauge-fill.warn  { background: #e8c00a; }
  .gauge-fill.error { background: var(--red-acc); }
  .gauge-ticks { display: flex; justify-content: space-between; margin-top: 4px; }
  .gauge-ticks span { font-family: 'Barlow Condensed', sans-serif; font-size: 0.65rem; color: var(--gray-500); }
  .result-item { display: flex; flex-direction: column; gap: 2px; padding: 8px 8px 8px 12px; border-bottom: 1px solid var(--border); }
  .result-item:last-child { border-bottom: none; }
  .result-label { font-family: 'Barlow Condensed', sans-serif; font-size: 0.7rem; font-weight: 600; letter-spacing: 0.12em; text-transform: uppercase; color: var(--amber); }
  .result-value { font-family: 'Oswald', sans-serif; font-size: 1.15rem; font-weight: 500; color: var(--white); letter-spacing: 0.02em; }
  .result-section-head { font-family: 'Barlow Condensed', sans-serif; font-size: 0.68rem; font-weight: 700; letter-spacing: 0.14em; text-transform: uppercase; color: var(--gray-500); background: var(--bg3); padding: 5px 12px; border-bottom: 1px solid var(--border); margin-top: 2px; }
  .result-note { font-size: 0.78rem; color: var(--gray-300); background: var(--bg3); border: 1px solid var(--border); border-radius: 3px; padding: 8px 12px; line-height: 1.5; margin-top: 0.5rem; }
  .result-note.warn  { border-color: #e8c00a; color: #e8d060; }
  .result-note.error { border-color: var(--red-acc); color: #e07060; }

  /* ── 100% MODE TOGGLE ── */
  .toggle-row {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 9px 12px;
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: 3px;
    cursor: pointer;
    user-select: none;
    transition: border-color 0.15s;
  }
  .toggle-row:hover { border-color: var(--border2); }
  .toggle-row.active { border-color: var(--amber); background: var(--amber-pale); }
  .toggle-checkbox {
    width: 16px; height: 16px;
    appearance: none; -webkit-appearance: none;
    background: var(--bg3);
    border: 2px solid var(--border2);
    border-radius: 3px;
    cursor: pointer;
    position: relative;
    flex-shrink: 0;
    transition: all 0.15s;
  }
  .toggle-checkbox:checked {
    background: var(--amber);
    border-color: var(--amber);
  }
  .toggle-checkbox:checked::after {
    content: '';
    position: absolute;
    left: 3px; top: 0px;
    width: 5px; height: 9px;
    border: 2px solid #1a1a18;
    border-top: none; border-left: none;
    transform: rotate(45deg);
  }
  .toggle-label {
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.78rem;
    font-weight: 600;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--gray-300);
    line-height: 1.3;
  }
  .toggle-row.active .toggle-label { color: var(--amber); }

  .preview-badge { display: inline-flex; align-items: center; gap: 6px; background: var(--amber-pale); border: 1px solid var(--amber-d); border-radius: 3px; padding: 4px 10px; font-family: 'Barlow Condensed', sans-serif; font-size: 0.72rem; font-weight: 700; letter-spacing: 0.12em; text-transform: uppercase; color: var(--amber); margin-bottom: 1.25rem; }
  footer { text-align: center; padding: 2rem; color: var(--gray-500); font-size: 0.78rem; border-top: 1px solid var(--border); margin-top: 2rem; line-height: 1.6; }
  /* ── NAV LINKS (multi-page version) ── */
  .calc-nav a {
    background: transparent;
    border: 2px solid transparent;
    border-radius: 3px;
    padding: 8px 16px;
    font-family: 'Barlow Condensed', sans-serif;
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--gray-300);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 6px;
    white-space: nowrap;
    text-decoration: none;
    transition: color 0.15s, background 0.15s;
  }
  .calc-nav a:hover:not(.active) {
    color: var(--white);
    background: var(--border);
    border-color: var(--border);
  }
  .calc-nav a.active {
    background: var(--amber);
    color: #1a1a18;
    border-color: var(--amber);
  }