:root {
    --ink: #0f0e0c;
    --paper: #faf8f4;
    --cream: #f2ede3;
    --accent: #c8502a;
    --accent-light: #f0ddd5;
    --muted: #8a8270;
    --border: #e0d9cc;
    --gold: #b8964a;
  }

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

  body {
    font-family: 'DM Sans', sans-serif;
    background: var(--paper);
    color: var(--ink);
    min-height: 100vh;
  }

  /* HEADER */
  header {
    background: var(--ink);
    color: var(--paper);
    padding: 18px 40px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 2px solid var(--accent);
  }

  .logo {
    font-family: 'Playfair Display', serif;
    font-size: 1.5rem;
    letter-spacing: -0.02em;
  }
  .logo span { color: var(--accent); }

  .header-actions { display: flex; gap: 12px; }

  .btn {
    font-family: 'DM Mono', monospace;
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    padding: 10px 20px;
    border: none;
    cursor: pointer;
    transition: all 0.2s;
  }

  .btn-ghost {
    background: transparent;
    color: var(--paper);
    border: 1px solid rgba(255,255,255,0.25);
  }
  .btn-ghost:hover { border-color: var(--paper); }

  .btn-accent {
    background: var(--accent);
    color: #fff;
  }
  .btn-accent:hover { background: #b04322; transform: translateY(-1px); }

  /* LAYOUT */
  .app {
    display: grid;
    grid-template-columns: 1fr 1fr;
    min-height: calc(100vh - 60px);
  }

  /* FORM PANEL */
  .form-panel {
    padding: 40px;
    overflow-y: auto;
    border-right: 1px solid var(--border);
    max-height: calc(100vh - 60px);
  }

  .section {
    margin-bottom: 36px;
    animation: fadeUp 0.4s ease both;
  }

  @keyframes fadeUp {
    from { opacity: 0; transform: translateY(12px); }
    to   { opacity: 1; transform: translateY(0); }
  }

  .section:nth-child(1) { animation-delay: 0.05s; }
  .section:nth-child(2) { animation-delay: 0.1s; }
  .section:nth-child(3) { animation-delay: 0.15s; }
  .section:nth-child(4) { animation-delay: 0.2s; }
  .section:nth-child(5) { animation-delay: 0.25s; }

  .section-title {
    font-family: 'DM Mono', monospace;
    font-size: 0.68rem;
    font-weight: 500;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--accent);
    margin-bottom: 16px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--border);
  }

  .form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
  .form-grid.full { grid-template-columns: 1fr; }

  .field { display: flex; flex-direction: column; gap: 5px; }
  .field label {
    font-size: 0.72rem;
    color: var(--muted);
    font-weight: 500;
    letter-spacing: 0.03em;
  }

  .field input, .field textarea, .field select {
    font-family: 'DM Sans', sans-serif;
    font-size: 0.88rem;
    padding: 9px 12px;
    border: 1px solid var(--border);
    background: #fff;
    color: var(--ink);
    outline: none;
    transition: border 0.2s;
    border-radius: 2px;
  }

  .field input:focus, .field textarea:focus, .field select:focus {
    border-color: var(--accent);
  }

  .field textarea { resize: vertical; min-height: 70px; }

  /* ITEMS TABLE */
  .items-list { display: flex; flex-direction: column; gap: 8px; }

  .item-row {
    display: grid;
    grid-template-columns: 3fr 1fr 1.2fr auto;
    gap: 8px;
    align-items: center;
    background: #fff;
    padding: 10px;
    border: 1px solid var(--border);
    border-radius: 2px;
    transition: border 0.2s;
  }
  .item-row:hover { border-color: var(--accent); }

  .item-row input {
    font-family: 'DM Sans', sans-serif;
    font-size: 0.85rem;
    padding: 6px 8px;
    border: 1px solid transparent;
    background: transparent;
    color: var(--ink);
    outline: none;
    width: 100%;
    transition: border 0.2s, background 0.2s;
    border-radius: 2px;
  }
  .item-row input:focus { border-color: var(--border); background: var(--paper); }

  .remove-btn {
    background: none;
    border: none;
    color: var(--muted);
    cursor: pointer;
    font-size: 1rem;
    padding: 4px;
    line-height: 1;
    transition: color 0.2s;
  }
  .remove-btn:hover { color: var(--accent); }

  .add-item-btn {
    font-family: 'DM Mono', monospace;
    font-size: 0.72rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--accent);
    background: var(--accent-light);
    border: 1px dashed var(--accent);
    padding: 10px;
    cursor: pointer;
    width: 100%;
    margin-top: 8px;
    transition: background 0.2s;
    border-radius: 2px;
  }
  .add-item-btn:hover { background: #e8c9bf; }

  .items-header {
    display: grid;
    grid-template-columns: 3fr 1fr 1.2fr auto;
    gap: 8px;
    padding: 0 10px 6px;
  }
  .items-header span {
    font-size: 0.68rem;
    font-weight: 500;
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: 0.06em;
  }

  /* PREVIEW PANEL */
  .preview-panel {
    background: var(--cream);
    padding: 40px;
    overflow-y: auto;
    max-height: calc(100vh - 60px);
    display: flex;
    justify-content: center;
  }

  /* INVOICE PREVIEW */
  #invoice-preview {
    background: #fff;
    width: 100%;
    max-width: 640px;
    padding: 52px 56px;
    box-shadow: 0 8px 40px rgba(0,0,0,0.12);
    font-size: 0.88rem;
    line-height: 1.6;
    height: fit-content;
  }

  .inv-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 48px;
  }

  .inv-company-name {
    font-family: 'Playfair Display', serif;
    font-size: 1.7rem;
    color: var(--ink);
    line-height: 1.1;
  }

  .inv-badge { text-align: right; }

  .inv-badge .inv-word {
    font-family: 'DM Mono', monospace;
    font-size: 0.65rem;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--muted);
    display: block;
  }

  .inv-badge .inv-number {
    font-family: 'Playfair Display', serif;
    font-size: 1.4rem;
    color: var(--accent);
  }

  .inv-divider {
    height: 2px;
    background: var(--ink);
    margin-bottom: 32px;
    position: relative;
  }
  .inv-divider::after {
    content: '';
    position: absolute;
    left: 0; top: 4px;
    width: 40px; height: 1px;
    background: var(--accent);
  }

  .inv-parties {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
  }

  .inv-party-label {
    font-family: 'DM Mono', monospace;
    font-size: 0.62rem;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    color: var(--accent);
    margin-bottom: 8px;
  }

  .inv-party-name {
    font-weight: 600;
    font-size: 0.95rem;
    margin-bottom: 4px;
  }

  .inv-party-details {
    font-size: 0.82rem;
    color: var(--muted);
    white-space: pre-line;
  }

  .inv-meta {
    display: flex;
    gap: 40px;
    margin-bottom: 36px;
    background: var(--cream);
    padding: 16px 20px;
    border-left: 3px solid var(--accent);
  }

  .inv-meta-item label {
    font-family: 'DM Mono', monospace;
    font-size: 0.6rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--muted);
    display: block;
  }

  .inv-meta-item span {
    font-size: 0.88rem;
    font-weight: 500;
  }

  /* INVOICE TABLE */
  .inv-table { width: 100%; border-collapse: collapse; margin-bottom: 24px; }

  .inv-table thead tr {
    background: var(--ink);
    color: var(--paper);
  }

  .inv-table thead th {
    font-family: 'DM Mono', monospace;
    font-size: 0.62rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    padding: 10px 12px;
    text-align: left;
    font-weight: 400;
  }
  .inv-table thead th:last-child { text-align: right; }

  .inv-table tbody tr { border-bottom: 1px solid var(--border); }
  .inv-table tbody tr:nth-child(even) { background: var(--cream); }

  .inv-table tbody td { padding: 11px 12px; font-size: 0.85rem; }
  .inv-table tbody td:last-child { text-align: right; font-family: 'DM Mono', monospace; }
  .inv-table tbody td:nth-child(2), .inv-table tbody td:nth-child(3) {
    font-family: 'DM Mono', monospace;
    font-size: 0.82rem;
    color: var(--muted);
  }

  /* TOTALS */
  .inv-totals {
    margin-left: auto;
    width: 260px;
    border-top: 2px solid var(--ink);
    padding-top: 16px;
  }

  .inv-total-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
    font-size: 0.85rem;
  }

  .inv-total-row label { color: var(--muted); }
  .inv-total-row span { font-family: 'DM Mono', monospace; }

  .inv-total-row.grand {
    border-top: 1px solid var(--border);
    padding-top: 10px;
    margin-top: 8px;
    font-size: 1rem;
    font-weight: 600;
  }
  .inv-total-row.grand label { color: var(--ink); }
  .inv-total-row.grand span { color: var(--accent); font-weight: 700; }

  .inv-notes {
    margin-top: 40px;
    padding: 16px 20px;
    border: 1px solid var(--border);
    font-size: 0.82rem;
    color: var(--muted);
    line-height: 1.7;
  }
  .inv-notes-label {
    font-family: 'DM Mono', monospace;
    font-size: 0.6rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--ink);
    display: block;
    margin-bottom: 6px;
  }

  .inv-footer {
    margin-top: 48px;
    padding-top: 16px;
    border-top: 1px solid var(--border);
    font-size: 0.75rem;
    color: var(--muted);
    font-family: 'DM Mono', monospace;
    display: flex;
    justify-content: space-between;
    letter-spacing: 0.04em;
  }

  /* RESPONSIVE */
  @media (max-width: 900px) {
    header { padding: 14px 20px; }
    .app { grid-template-columns: 1fr; }
    .preview-panel { max-height: none; }
    .form-panel {
      max-height: none;
      border-right: none;
      border-bottom: 1px solid var(--border);
      padding: 28px 24px;
    }
    #invoice-preview { padding: 36px 32px; }
  }

  /* ── Mobile tabs: switch between form and preview ── */
  .mobile-tabs {
    display: none;
  }
  @media (max-width: 650px) {
    .mobile-tabs {
      display: flex;
      background: var(--ink);
      border-bottom: 1px solid #2a2010;
      position: sticky;
      top: 0;
      z-index: 90;
    }
    .mobile-tab {
      flex: 1;
      font-family: 'DM Mono', monospace;
      font-size: 0.68rem;
      letter-spacing: 0.1em;
      text-transform: uppercase;
      padding: 11px 6px;
      text-align: center;
      color: var(--muted);
      background: none;
      border: none;
      border-bottom: 2px solid transparent;
      cursor: pointer;
      transition: all 0.18s;
    }
    .mobile-tab.active {
      color: var(--accent);
      border-bottom-color: var(--accent);
    }
  }

  /* ── Mobile (≤ 650px) ── */
  @media (max-width: 650px) {
    body { overflow-x: hidden; }

    /* Header */
    header {
      padding: 10px 14px;
      flex-wrap: wrap;
      gap: 8px;
      position: sticky;
      top: 0;
      z-index: 100;
    }
    .logo { font-size: 1.2rem; }
    .header-actions { gap: 7px; }
    .btn { font-size: 0.65rem; padding: 8px 12px; }

    /* App layout: single column, tab-driven */
    .app {
      grid-template-columns: 1fr;
      min-height: auto;
    }

    /* Form panel */
    .form-panel {
      padding: 20px 14px;
      max-height: none;
      border: none;
      overflow: visible;
    }
    .form-panel.hidden { display: none; }

    /* Form grid: single column on mobile */
    .form-grid { grid-template-columns: 1fr; gap: 10px; }

    /* Field inputs: bigger touch targets */
    .field input,
    .field textarea,
    .field select {
      font-size: 1rem; /* prevents zoom on iOS */
      padding: 11px 12px;
    }
    .field textarea { min-height: 60px; }

    /* Section spacing */
    .section { margin-bottom: 26px; }
    .section-title { font-size: 0.65rem; margin-bottom: 12px; }

    /* Items table header: hide on mobile (labels on items directly) */
    .items-header { display: none; }

    /* Item rows: stack vertically on mobile */
    .item-row {
      grid-template-columns: 1fr 1fr;
      grid-template-rows: auto auto;
      gap: 6px;
      padding: 12px 10px;
    }
    .item-row input:first-child {
      grid-column: 1 / -1; /* description spans full width */
      border: 1px solid var(--border) !important;
      background: var(--paper) !important;
      font-size: 0.95rem;
    }
    .item-row input:first-child::placeholder { font-size: 0.85rem; }
    .item-row input:not(:first-child) {
      border: 1px solid var(--border) !important;
      background: var(--paper) !important;
      font-size: 0.9rem;
      padding: 7px 8px;
    }
    /* Add qty/price labels via placeholder - handled by existing placeholder */
    .remove-btn { justify-self: end; align-self: center; font-size: 1.1rem; padding: 6px 8px; }

    .add-item-btn { font-size: 0.75rem; padding: 13px; }

    /* Preview panel */
    .preview-panel {
      padding: 16px 10px 30px;
      background: var(--cream);
    }
    .preview-panel.hidden { display: none; }

    #invoice-preview {
      padding: 24px 18px;
      font-size: 0.82rem;
      max-width: 100%;
      box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    }

    /* Invoice preview: compact for mobile */
    .inv-header { margin-bottom: 24px; flex-direction: column; gap: 12px; }
    .inv-badge { text-align: left; }
    .inv-company-name { font-size: 1.3rem; }
    .inv-badge .inv-number { font-size: 1.1rem; }

    .inv-parties {
      grid-template-columns: 1fr;
      gap: 20px;
      margin-bottom: 24px;
    }

    .inv-meta {
      flex-direction: column;
      gap: 12px;
      padding: 12px 14px;
      margin-bottom: 22px;
    }

    .inv-table thead th { font-size: 0.55rem; padding: 8px 8px; }
    .inv-table tbody td { padding: 8px 8px; font-size: 0.78rem; }

    .inv-totals { width: 100%; margin-left: 0; }
    .inv-total-row { font-size: 0.82rem; }
    .inv-total-row.grand { font-size: 0.92rem; }

    .inv-footer {
      flex-direction: column;
      gap: 4px;
      font-size: 0.68rem;
      margin-top: 28px;
    }

    .inv-notes { margin-top: 24px; font-size: 0.78rem; }
    .inv-divider { margin-bottom: 20px; }
  }

  /* ── Very small (≤ 380px) ── */
  @media (max-width: 380px) {
    header { padding: 8px 10px; }
    .logo { font-size: 1rem; }
    .btn { font-size: 0.58rem; padding: 7px 9px; }
    .form-panel { padding: 16px 10px; }
    #invoice-preview { padding: 18px 12px; }
    .inv-company-name { font-size: 1.1rem; }
    /* Items: full stack */
    .item-row { grid-template-columns: 1fr; }
    .item-row input:first-child { grid-column: 1; }
    .remove-btn { justify-self: start; }
  }

  @media print {
    header, .form-panel, .mobile-tabs { display: none; }
    .preview-panel { padding: 0; background: #fff; }
    #invoice-preview { box-shadow: none; }
  }

  .currency-select {
    font-family: 'DM Mono', monospace;
    font-size: 0.82rem;
  }