:root {
  --bg: #f4f6f9;
  --card: #ffffff;
  --text: #1c2430;
  --muted: #5b6676;
  --border: #dde3ea;
  --accent: #0b6bcb;
  --accent-soft: #e6f0fb;
  --good: #1a7f4b;
  --good-soft: #e5f5ec;
  --warn: #9a5b00;
  --warn-soft: #fff4e0;
  --radius: 12px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #11161d;
    --card: #1a212b;
    --text: #e6ebf1;
    --muted: #9aa6b5;
    --border: #2c3644;
    --accent: #5aa7f2;
    --accent-soft: #1b2c40;
    --good: #5fd39a;
    --good-soft: #17332a;
    --warn: #f2b45a;
    --warn-soft: #3a2c15;
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

.top { padding: 20px 16px 8px; max-width: 1200px; margin: 0 auto; }
.top h1 { margin: 0; font-size: 1.4rem; }
.sub { margin: 4px 0 0; color: var(--muted); }

.layout {
  max-width: 1200px;
  margin: 0 auto;
  padding: 8px 16px 24px;
  display: grid;
  gap: 16px;
  grid-template-columns: 1fr;
}

@media (min-width: 900px) {
  .layout { grid-template-columns: minmax(340px, 5fr) 7fr; align-items: start; }
  .results { position: sticky; top: 12px; }
}

.inputs, .results { display: flex; flex-direction: column; gap: 16px; min-width: 0; }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
}
.card h2 { margin: 0 0 12px; font-size: 1.05rem; }
.card.highlight { border-color: var(--accent); }

details.card summary { cursor: pointer; list-style: none; }
details.card summary::-webkit-details-marker { display: none; }
details.card summary h2 { display: inline; margin: 0; }
details.card summary::after { content: " ▾"; color: var(--muted); }
details.card[open] summary { margin-bottom: 12px; }

.grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.span-2 { grid-column: span 2; }

label { display: flex; flex-direction: column; gap: 4px; font-size: 0.875rem; color: var(--muted); }

input, select {
  font: inherit;
  font-size: 16px; /* >=16px để iOS không tự zoom khi chạm vào ô */
  color: var(--text);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
  min-height: 44px;
  width: 100%;
}
input:focus, select:focus { outline: 2px solid var(--accent); outline-offset: 1px; }

.group-head { display: flex; gap: 8px; margin-bottom: 12px; }
.g-name { font-weight: 600; }
.g-remove {
  flex: 0 0 44px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--muted);
  border-radius: 8px;
  font-size: 1rem;
  cursor: pointer;
}
.g-remove:hover { color: #c0392b; border-color: #c0392b; }
.g-activity-wrap[hidden] { display: none; }

.btn-secondary {
  font: inherit;
  min-height: 48px;
  border: 1px dashed var(--accent);
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: var(--radius);
  cursor: pointer;
  font-weight: 600;
}

.stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.stat { display: flex; flex-direction: column; min-width: 0; }
.stat-label { font-size: 0.8rem; color: var(--muted); }
.stat-value { font-size: 1.6rem; font-weight: 700; color: var(--accent); line-height: 1.2; font-variant-numeric: tabular-nums; }
.stat-note { font-size: 0.78rem; color: var(--muted); }

@media (max-width: 480px) {
  .stats { grid-template-columns: 1fr 1fr; }
  .stat:first-child { grid-column: span 2; }
  .stat-value { font-size: 1.4rem; }
}

.reco {
  margin: 14px 0 0;
  padding: 10px 12px;
  background: var(--good-soft);
  color: var(--good);
  border-radius: 8px;
  font-weight: 600;
}
.reco:empty { display: none; }

.warnings { margin: 10px 0 0; padding: 0; list-style: none; display: flex; flex-direction: column; gap: 6px; }
.warnings li { padding: 8px 12px; background: var(--warn-soft); color: var(--warn); border-radius: 8px; font-size: 0.9rem; }

.table-wrap { overflow-x: auto; -webkit-overflow-scrolling: touch; }
table { width: 100%; border-collapse: collapse; font-size: 0.9rem; font-variant-numeric: tabular-nums; }
th, td { text-align: left; padding: 8px 6px; border-bottom: 1px solid var(--border); white-space: nowrap; }
th { color: var(--muted); font-weight: 600; font-size: 0.8rem; }
#group-table td:first-child { white-space: normal; min-width: 7.5em; }
@media (max-width: 480px) { table { font-size: 0.82rem; } th, td { padding: 8px 4px; } }
tr.best td { background: var(--good-soft); color: var(--good); font-weight: 600; }
tr.over td { color: var(--muted); }

.muted { color: var(--muted); font-size: 0.875rem; }
.formula {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.82rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
  overflow-x: auto;
}

.foot { max-width: 1200px; margin: 0 auto; padding: 0 16px 32px; color: var(--muted); font-size: 0.8rem; }

/* ---------- Thanh thương hiệu ---------- */
.brand { background: var(--accent); color: #fff; }
.brand-inner {
  max-width: 1200px; margin: 0 auto; padding: 10px 16px;
  display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap;
}
.brand-name { font-weight: 800; font-size: 1.1rem; letter-spacing: 0.02em; }
.brand-phone { color: #fff; text-decoration: none; font-weight: 600; white-space: nowrap; }
@media (prefers-color-scheme: dark) { .brand { background: #0b4f96; } }

.project-card { display: flex; flex-direction: column; gap: 12px; }

.btn-primary {
  font: inherit; font-weight: 700; width: 100%; min-height: 48px; margin-top: 14px;
  border: 0; border-radius: var(--radius); background: var(--accent); color: #fff; cursor: pointer;
}
@media (prefers-color-scheme: dark) { .btn-primary { background: #0b6bcb; } }
.pdf-hint { margin: 6px 0 0; font-size: 0.78rem; }

/* ---------- Báo cáo PDF (chỉ hiện khi in) ---------- */
.report { display: none; }

@media print {
  @page { size: A4; margin: 14mm 12mm; }
  body { background: #fff; color: #000; font-size: 11pt; }
  body > *:not(.report) { display: none !important; }
  .report { display: block; -webkit-print-color-adjust: exact; print-color-adjust: exact; }
  .report table { font-size: 9.5pt; margin-bottom: 4mm; }
  .report th, .report td { border: 1px solid #999; padding: 4px 6px; white-space: normal; color: #000; }
  .report th { background: #eef3f9; color: #000; }
  .rp-head { display: flex; justify-content: space-between; align-items: flex-start; border-bottom: 2px solid #0b6bcb; padding-bottom: 3mm; }
  .rp-company { font-size: 16pt; font-weight: 800; color: #0b6bcb; }
  .rp-phone, .rp-date { font-size: 10pt; }
  .rp-title { font-size: 14pt; text-align: center; margin: 6mm 0 2mm; }
  .rp-project { text-align: center; font-size: 12pt; font-weight: 600; margin: 0 0 1mm; }
  .rp-client { text-align: center; font-size: 11pt; margin: 0 0 5mm; }
  .report h2 { font-size: 11.5pt; margin: 4mm 0 2mm; }
  .rp-reco { font-weight: 700; border: 1px solid #1a7f4b; padding: 3mm; margin: 2mm 0; }
  .rp-warn { font-size: 9.5pt; margin: 1mm 0; }
  .rp-note { font-size: 9pt; margin: -2mm 0 2mm; }
  .rp-foot { margin-top: 6mm; font-size: 8.5pt; color: #444; border-top: 1px solid #ccc; padding-top: 2mm; }
  .report table, .rp-reco { break-inside: avoid; }
}