:root{
  --ink:#0f172a; --ink-600:#334155; --muted:#64748b; --line:#e2e8f0;
  --bg:#f8fafc; --white:#fff; --danger:#dc2626;
  --radius:12px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  font-family:ui-sans-serif,system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  background:var(--bg); color:var(--ink); -webkit-font-smoothing:antialiased;
}
.page{min-height:100vh;padding:16px}
.wrap{max-width:1120px;margin:0 auto}
.hidden{display:none !important}
.muted{color:var(--muted)}
.small{font-size:12px}
.strong{font-weight:700}
.right{text-align:right}
.center{text-align:center}
.pre{white-space:pre-line}

/* top bar */
.topbar{display:flex;flex-direction:column;gap:16px;margin-bottom:24px}
.topbar h1{font-size:26px;margin:0;letter-spacing:-.02em}
.topbar p{margin:4px 0 0;font-size:13px}
.actions{display:flex;gap:10px;flex-wrap:wrap}
.btn{
  flex:1 1 auto;min-height:40px;padding:0 16px;border-radius:10px;border:1px solid var(--ink);
  background:var(--ink);color:#fff;font-size:14px;font-weight:600;cursor:pointer;
}
.btn:hover{opacity:.9}
.btn.ghost{background:#fff;color:var(--ink);border-color:var(--line);box-shadow:0 1px 2px rgba(15,23,42,.05)}
.btn.small{flex:0 0 auto;min-height:32px;font-size:12px;padding:0 12px}

/* tabs */
.tabs{display:grid;grid-template-columns:1fr 1fr;gap:4px;background:#f1f5f9;padding:4px;border-radius:10px;max-width:420px;margin-bottom:24px}
.tab{border:0;background:transparent;padding:8px 12px;border-radius:8px;font-size:14px;font-weight:600;color:var(--muted);cursor:pointer}
.tab.active{background:#fff;color:var(--ink);box-shadow:0 1px 2px rgba(15,23,42,.08)}

/* cards */
.grid12{display:grid;gap:20px}
.col8,.col4{display:grid;gap:20px;align-content:start}
.card{background:#fff;border-radius:var(--radius);box-shadow:0 1px 3px rgba(15,23,42,.08);overflow:hidden}
.accent{height:4px;background:var(--ink)}
.card-head{display:flex;align-items:center;gap:8px;padding:18px 20px 8px}
.card-head h2{font-size:17px;margin:0;font-weight:700;flex:1}
.mark{width:4px;height:20px;border-radius:99px;background:var(--ink);display:inline-block}
.card-body{padding:12px 20px 22px;display:grid;gap:16px}
.grid2{grid-template-columns:1fr}
.field{display:grid;gap:6px}
label{font-size:13px;font-weight:600;color:var(--ink-600)}
input,select,textarea{
  width:100%;font:inherit;font-size:14px;padding:9px 12px;border:1px solid var(--line);
  border-radius:9px;background:#fff;color:var(--ink);
}
input:focus,select:focus,textarea:focus{outline:2px solid rgba(15,23,42,.15);border-color:var(--ink)}
textarea{resize:vertical}
.scroll-x{overflow-x:auto}

/* items table */
table.items{width:100%;border-collapse:collapse;min-width:620px}
table.items th{font-size:12px;text-transform:uppercase;letter-spacing:.04em;color:var(--muted);text-align:left;padding:8px 6px;border-bottom:1px solid var(--line)}
table.items td{padding:8px 6px;border-bottom:1px solid #f1f5f9;font-size:14px;vertical-align:middle}
table.items input[type=number]{width:88px}
.icon-btn{border:0;background:transparent;color:var(--danger);cursor:pointer;font-size:16px;padding:6px}

.totals-mini{border-top:1px solid var(--line);padding-top:14px;display:grid;gap:8px;font-size:14px}
.totals-mini div{display:flex;justify-content:space-between}
.totals-mini .strong{font-weight:700;font-size:18px}
.totals-mini .due{color:var(--danger);font-weight:600}

/* preview sheet */
.sheet{
  position:relative;background:#fff;color:#000;max-width:840px;margin:0 auto 48px;
  padding:28px 28px 170px;border-radius:12px;box-shadow:0 25px 50px -12px rgba(15,23,42,.25);
}
.stamp{position:absolute;right:36px;bottom:30px;width:120px;opacity:.8;transform:rotate(-15deg);pointer-events:none}
.stamp-partial{
  position:absolute;right:36px;bottom:36px;display:flex;flex-direction:column;align-items:center;justify-content:center;
  width:140px;height:140px;border:5px double #d97706;border-radius:50%;color:#d97706;
  font-weight:800;letter-spacing:.05em;transform:rotate(-15deg);opacity:.85;font-size:15px;
}
.sheet-top{display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap}
.logo{height:56px;width:auto;display:block;margin-bottom:14px}
.from{font-size:12px;color:var(--muted);max-width:280px;line-height:1.5}
.from p{margin:2px 0}
.from .strong{color:#000;font-size:14px}
.sheet-title{text-align:right}
.sheet-title h2{margin:0;font-size:38px;font-weight:200;letter-spacing:-.04em;color:#cbd5e1}
.sheet-title p{margin:2px 0}
.sheet-parties{display:grid;grid-template-columns:1fr;gap:20px;margin-top:26px;padding-top:22px;border-top:1px solid var(--line)}
.eyebrow{font-size:10px;font-weight:700;text-transform:uppercase;letter-spacing:.15em;color:#94a3b8;margin:0 0 8px}
.big{font-size:18px}
.box{background:#f8fafc;border-radius:10px;padding:14px}
.kv{display:flex;justify-content:space-between;font-size:13px;padding:2px 0}
.preview-table{width:100%;border-collapse:collapse;margin-top:28px;min-width:520px}
.preview-table thead th{background:var(--ink);color:#fff;font-size:12px;padding:10px;text-align:left}
.preview-table thead th.right{text-align:right}
.preview-table thead th.center{text-align:center}
.preview-table td{padding:12px 10px;border-bottom:1px solid #f1f5f9;font-size:14px}
.sheet-totals{display:flex;justify-content:flex-end;margin-top:26px}
.tcol{width:260px;display:grid;gap:10px;font-size:14px;color:var(--muted)}
.tcol div{display:flex;justify-content:space-between}
.tcol .grand{border-top:1px solid var(--line);padding-top:10px;font-size:20px;font-weight:700;color:#000}
.tcol .due{color:var(--danger);font-weight:700}
.sheet-foot{margin-top:48px;padding-top:20px;border-top:1px solid #f1f5f9;text-align:center;font-style:italic;color:#94a3b8;font-size:10px}

@media(min-width:640px){
  .page{padding:32px}
  .topbar{flex-direction:row;align-items:center;justify-content:space-between}
  .actions .btn{flex:0 0 auto}
  .grid2{grid-template-columns:1fr 1fr}
  .sheet{padding:48px 48px 180px}
  .sheet-parties{grid-template-columns:1fr 1fr;gap:40px}
  .logo{height:76px}
}
@media(min-width:1024px){
  .grid12{grid-template-columns:2fr 1fr}
}

@media print{
  body{background:#fff}
  .topbar,.tabs,#tab-editor{display:none !important}
  #tab-preview{display:block !important}
  .sheet{box-shadow:none;margin:0;max-width:none;padding:0}
}