*, *::before, *::after { box-sizing: border-box; }
    body { background: #f4f6fb; font-family: 'Inter', sans-serif; color: #1a1a2e; min-height: 100vh; }

    /* ── HEADER ── */
    .checkout-header {
      background: #fff;
      border-bottom: 1px solid #e8eaf0;
      padding: 14px 24px;
      display: flex;
      align-items: center;
      gap: 16px;
      position: sticky;
      top: 0;
      z-index: 100;
      box-shadow: 0 2px 8px rgba(0,0,0,.06);
    }
    .checkout-header img { height: 36px; }
    .checkout-header .back-link {
      font-size: 13px; color: #666; text-decoration: none; display: flex; align-items: center; gap: 6px;
    }
    .checkout-header .back-link:hover { color: #0a84ff; }
    .header-title { font-size: 16px; font-weight: 700; color: #1a1a2e; margin-left: auto; margin-right: auto; }

    /* ── LAYOUT ── */
    .checkout-wrapper {
      max-width: 1100px;
      margin: 32px auto;
      padding: 0 16px 60px;
      display: grid;
      grid-template-columns: 1fr 420px;
      gap: 28px;
      align-items: start;
    }
    @media (max-width: 900px) {
      .checkout-wrapper { grid-template-columns: 1fr; }
      .order-summary-col { order: -1; }
    }

    /* ── CARDS ── */
    .checkout-card {
      background: #fff;
      border-radius: 16px;
      padding: 28px;
      box-shadow: 0 2px 16px rgba(0,0,0,.07);
      margin-bottom: 20px;
    }
    .section-title {
      font-size: 13px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: .06em;
      color: #888;
      margin-bottom: 18px;
      padding-bottom: 10px;
      border-bottom: 1px solid #f0f0f0;
    }

    /* ── FORM ── */
    .form-label { font-size: 12px; font-weight: 600; color: #555; margin-bottom: 5px; }
    .form-control, .form-select {
      border: 1.5px solid #e2e6f0;
      border-radius: 10px;
      padding: 10px 14px;
      font-size: 14px;
      transition: border-color .2s, box-shadow .2s;
    }
    .form-control:focus, .form-select:focus {
      border-color: #0a84ff;
      box-shadow: 0 0 0 3px rgba(10,132,255,.12);
      outline: none;
    }
    .form-control.is-invalid { border-color: #ff3b30; }

    /* ── SAME-AS TOGGLE ── */
    .same-toggle {
      display: flex;
      align-items: center;
      gap: 10px;
      background: #f8f9ff;
      border: 1.5px solid #e2e6f0;
      border-radius: 10px;
      padding: 12px 16px;
      cursor: pointer;
      margin-bottom: 16px;
      transition: background .2s;
    }
    .same-toggle input { accent-color: #0a84ff; width: 16px; height: 16px; cursor: pointer; }
    .same-toggle label { font-size: 13px; font-weight: 500; color: #444; cursor: pointer; margin: 0; }

    /* ── ORDER SUMMARY ── */
    .order-item {
      display: flex;
      align-items: center;
      gap: 14px;
      padding: 14px 0;
      border-bottom: 1px solid #f4f4f4;
    }
    .order-item:last-child { border-bottom: none; }
    .order-item-img {
      width: 64px; height: 64px;
      border-radius: 10px;
      object-fit: cover;
      border: 1px solid #eee;
      background: #f8f8f8;
      flex-shrink: 0;
    }
    .order-item-name { font-size: 14px; font-weight: 600; color: #1a1a2e; line-height: 1.3; }
    .order-item-qty { font-size: 12px; color: #888; margin-top: 3px; }
    .order-item-price { margin-left: auto; font-size: 15px; font-weight: 700; color: #1a1a2e; white-space: nowrap; }

    .price-row {
      display: flex;
      justify-content: space-between;
      font-size: 14px;
      color: #555;
      padding: 7px 0;
    }
    .price-row.total {
      font-size: 18px;
      font-weight: 700;
      color: #1a1a2e;
      border-top: 2px solid #f0f0f0;
      margin-top: 6px;
      padding-top: 14px;
    }
    .savings-badge {
      background: #e8fff2;
      color: #1a9e4e;
      font-size: 11px;
      font-weight: 700;
      border-radius: 6px;
      padding: 3px 8px;
    }

    /* ── PAY BUTTON ── */
    .btn-pay {
      width: 100%;
      padding: 15px;
      background: linear-gradient(135deg, #0a84ff, #0060df);
      color: #fff;
      border: none;
      border-radius: 12px;
      font-size: 16px;
      font-weight: 700;
      cursor: pointer;
      transition: transform .15s, box-shadow .15s;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 10px;
      margin-top: 20px;
    }
    .btn-pay:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(10,132,255,.35); }
    .btn-pay:disabled { opacity: .6; cursor: not-allowed; transform: none; }

    .secure-note {
      text-align: center;
      font-size: 12px;
      color: #aaa;
      margin-top: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
    }

    /* ── GST SECTION ── */
    .gst-toggle-btn {
      background: none;
      border: 1.5px dashed #c0c8e0;
      border-radius: 10px;
      padding: 10px 16px;
      font-size: 13px;
      color: #0a84ff;
      font-weight: 600;
      cursor: pointer;
      width: 100%;
      text-align: left;
      transition: background .2s;
      margin-top: 4px;
    }
    .gst-toggle-btn:hover { background: #f0f5ff; }

    /* ── STEPS ── */
    .steps-bar {
      display: flex;
      align-items: center;
      gap: 0;
      font-size: 12px;
      font-weight: 600;
      color: #aaa;
      margin-bottom: 4px;
      flex-wrap: wrap;
      gap: 4px;
    }
    .step-active { color: #0a84ff; }
    .step-sep { color: #ddd; font-size: 10px; }

    /* ── EMPTY STATE ── */
    .empty-cart {
      text-align: center;
      padding: 60px 20px;
    }
    .empty-cart i { font-size: 48px; color: #ddd; margin-bottom: 16px; }
    .empty-cart p { color: #888; margin-bottom: 20px; }