:root {
    --bg: #0f1117;
    --surface: #1a1d27;
    --surface2: #22263a;
    --border: #2e3350;
    --accent: #4f6ef7;
    --accent-hover: #3d5be0;
    --accent2: #e94560;
    --success: #22c55e;
    --warning: #f59e0b;
    --text: #e2e8f0;
    --text-muted: #94a3b8;
    --text-dim: #64748b;
    --input-bg: #12151f;
    --radius: 8px;
    --radius-sm: 5px;
    --font: 'Segoe UI', system-ui, -apple-system, sans-serif;
    --mono: 'Cascadia Code', 'Fira Code', 'Consolas', monospace;
  }

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

  body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    padding: 0 0 60px 0;
  }

  /* ── Header ── */
  header {
    background: linear-gradient(135deg, #1a1d27 0%, #0f1117 100%);
    border-bottom: 1px solid var(--border);
    padding: 18px 32px;
    display: flex;
    align-items: center;
    gap: 14px;
    position: sticky;
    top: 0;
    z-index: 100;
  }
  header .logo {
    width: 36px; height: 36px;
    background: var(--accent);
    border-radius: 8px;
    display: flex; align-items: center; justify-content: center;
    font-weight: 700; font-size: 18px; color: #fff;
  }
  header h1 { font-size: 18px; font-weight: 600; color: var(--text); }
  header span { font-size: 12px; color: var(--text-muted); margin-left: auto; }

  /* ── Main layout ── */
  .container { max-width: 1100px; margin: 0 auto; padding: 28px 24px; }

  /* ── Mode tabs ── */
  .mode-tabs {
    display: flex;
    gap: 4px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 4px;
    margin-bottom: 24px;
    width: fit-content;
  }
  .mode-tab {
    padding: 10px 28px;
    border-radius: 7px;
    border: none;
    background: transparent;
    color: var(--text-muted);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all .2s;
  }
  .mode-tab.active {
    background: var(--accent);
    color: #fff;
    box-shadow: 0 2px 8px rgba(79,110,247,.4);
  }
  .mode-tab:hover:not(.active) { background: var(--surface2); color: var(--text); }

  /* ── Panel ── */
  .panel { display: none; }
  .panel.active { display: block; }

  /* ── Card ── */
  .card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 20px 24px;
    margin-bottom: 16px;
  }
  .card-title {
    font-size: 13px;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: .06em;
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 8px;
  }
  .card-title .badge {
    font-size: 10px;
    font-weight: 600;
    padding: 2px 6px;
    border-radius: 4px;
    text-transform: uppercase;
    letter-spacing: .04em;
  }
  .badge-req { background: rgba(233,69,96,.18); color: var(--accent2); }
  .badge-opt { background: rgba(79,110,247,.15); color: #7b9bff; }

  /* ── Grid ── */
  .grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 14px; }
  .grid-2 { grid-template-columns: 1fr 1fr; }
  .grid-3 { grid-template-columns: 1fr 1fr 1fr; }
  .full { grid-column: 1 / -1; }

  /* ── Form elements ── */
  .field { display: flex; flex-direction: column; gap: 5px; }
  .field label {
    font-size: 12px;
    color: var(--text-muted);
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 6px;
  }
  .field label .req { color: var(--accent2); font-size: 11px; }
  .field label .hint {
    color: var(--text-dim);
    font-size: 10px;
    font-style: italic;
    margin-left: auto;
  }
  input[type="text"], input[type="number"], select, textarea {
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-family: var(--font);
    font-size: 13px;
    padding: 8px 10px;
    width: 100%;
    transition: border-color .15s;
    outline: none;
  }
  input:focus, select:focus, textarea:focus { border-color: var(--accent); }
  input::placeholder, textarea::placeholder { color: var(--text-dim); }
  select option { background: #1e2235; }
  textarea { resize: vertical; min-height: 70px; }

  /* radio groups */
  .radio-group { display: flex; gap: 8px; flex-wrap: wrap; }
  .radio-pill {
    display: flex;
    align-items: center;
    gap: 5px;
    padding: 6px 12px;
    border: 1px solid var(--border);
    border-radius: 20px;
    cursor: pointer;
    font-size: 12px;
    color: var(--text-muted);
    transition: all .15s;
    user-select: none;
  }
  .radio-pill input[type="radio"] { display: none; }
  .radio-pill:has(input:checked) {
    border-color: var(--accent);
    background: rgba(79,110,247,.12);
    color: var(--text);
  }

  /* ── Items builder ── */
  .items-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 12px; }
  .item-row {
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 14px;
    margin-bottom: 10px;
  }
  .item-row-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 10px;
  }
  .item-num { font-size: 12px; font-weight: 600; color: var(--accent); }

  /* ── Accordion ── */
  .accordion {
    border: 1px solid var(--border);
    border-radius: var(--radius);
    margin-bottom: 10px;
    overflow: hidden;
  }
  .accordion-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 13px 18px;
    background: var(--surface);
    cursor: pointer;
    user-select: none;
    transition: background .15s;
    gap: 10px;
  }
  .accordion-header:hover { background: var(--surface2); }
  .accordion-header .acc-title { font-size: 13px; font-weight: 600; color: var(--text); }
  .accordion-header .acc-desc { font-size: 11px; color: var(--text-muted); flex: 1; }
  .accordion-arrow { color: var(--text-muted); transition: transform .2s; font-size: 12px; }
  .accordion.open .accordion-arrow { transform: rotate(180deg); }
  .accordion-body { display: none; padding: 16px 18px; background: var(--surface2); }
  .accordion.open .accordion-body { display: block; }

  /* ── Buttons ── */
  .btn {
    padding: 9px 18px;
    border: none;
    border-radius: var(--radius-sm);
    font-family: var(--font);
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all .15s;
    display: inline-flex;
    align-items: center;
    gap: 6px;
  }
  .btn-primary { background: var(--accent); color: #fff; }
  .btn-primary:hover { background: var(--accent-hover); }
  .btn-danger { background: rgba(233,69,96,.15); color: var(--accent2); border: 1px solid rgba(233,69,96,.3); }
  .btn-danger:hover { background: rgba(233,69,96,.25); }
  .btn-secondary { background: var(--surface2); color: var(--text); border: 1px solid var(--border); }
  .btn-secondary:hover { background: var(--border); }
  .btn-success { background: #16a34a; color: #fff; }
  .btn-success:hover { background: #15803d; }
  .btn-sm { padding: 5px 11px; font-size: 12px; }

  /* ── Result area ── */
  .result-section { margin-top: 20px; }
  .result-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 10px;
    overflow: hidden;
  }
  .result-card-header {
    padding: 12px 18px;
    background: var(--surface2);
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: space-between;
  }
  .result-card-header span { font-size: 13px; font-weight: 600; }
  .result-card-body { padding: 16px 18px; }
  .code-block {
    font-family: var(--mono);
    font-size: 12px;
    background: var(--input-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 12px 14px;
    word-break: break-all;
    color: #a5b4fc;
    line-height: 1.6;
    margin-top: 8px;
  }
  .code-block.url-block { color: #86efac; }
  .label-sm { font-size: 11px; color: var(--text-muted); text-transform: uppercase; letter-spacing: .05em; margin-top: 14px; margin-bottom: 4px; }
  .label-sm:first-child { margin-top: 0; }

  /* ── Action bar ── */
  .action-bar {
    display: flex;
    gap: 10px;
    align-items: center;
    flex-wrap: wrap;
    margin-top: 8px;
  }

  /* iframe result */
  #iframeContainer { display: none; margin-top: 16px; }
  #iframeContainer iframe { border: none; width: 100%; border-radius: var(--radius-sm); display: block; }

  /* ── Env badge ── */
  .env-indicator {
    font-size: 11px;
    font-weight: 700;
    padding: 3px 8px;
    border-radius: 4px;
    text-transform: uppercase;
    letter-spacing: .05em;
  }
  .env-prod { background: rgba(233,69,96,.2); color: #f87171; }
  .env-test { background: rgba(34,197,94,.15); color: #4ade80; }

  /* ── Timestamp ── */
  .ts-row { display: flex; gap: 8px; align-items: flex-end; }
  .ts-row .field { flex: 1; }

  /* ── Amount row ── */
  .amount-row {
    background: var(--surface2);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 10px 14px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 10px;
  }
  .amount-label { font-size: 12px; color: var(--text-muted); }
  .amount-value { font-size: 16px; font-weight: 700; color: var(--accent); font-family: var(--mono); }

  /* ── Scrollbar ── */
  ::-webkit-scrollbar { width: 6px; height: 6px; }
  ::-webkit-scrollbar-track { background: var(--bg); }
  ::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

  /* ── Custom fields row ── */
  .kv-row { display: flex; gap: 8px; align-items: center; margin-bottom: 8px; }
  .kv-row input { flex: 1; }

  /* ── Divider ── */
  .divider { border: none; border-top: 1px solid var(--border); margin: 14px 0; }

  /* ── QR placeholder ── */
  #qrResult { margin-top: 10px; }

  /* Responsive */
  @media (max-width: 700px) {
    .grid-2, .grid-3 { grid-template-columns: 1fr; }
    .container { padding: 16px 12px; }
    header { padding: 14px 16px; }
  }

  /* Copy button flash */
  .copied { color: var(--success) !important; }

  /* Subscription mode highlight */
  .sub-highlight {
    border-left: 3px solid var(--warning);
    padding-left: 12px;
    background: rgba(245,158,11,.05);
    border-radius: 0 4px 4px 0;
  }