:root {
  --bg: #f4f6f9;
  --panel: #ffffff;
  --primary: #0b6bcb;
  --primary-dark: #09529e;
  --text: #1d2733;
  --muted: #5b6b7b;
  --border: #d9e0e8;
  --accent: #e8f1fb;
  --ok: #1f9d55;
  --shadow: 0 1px 3px rgba(20,40,70,.08), 0 6px 18px rgba(20,40,70,.06);
  --radius: 10px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", system-ui, -apple-system, "Helvetica Neue", "PingFang SC",
    "Hiragino Sans", "Microsoft YaHei", "Noto Sans CJK", sans-serif;
  font-size: 15px;
  line-height: 1.55;
}

a { color: var(--primary); }

/* ---------- Top bar ---------- */
.topbar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 18px;
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 50;
  flex-wrap: wrap;
}
.topbar .brand {
  font-weight: 700;
  font-size: 17px;
  color: var(--primary-dark);
  margin-right: auto;
  letter-spacing: .2px;
}
.topbar .brand small {
  display: block;
  font-weight: 400;
  font-size: 11px;
  color: var(--muted);
  letter-spacing: .3px;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  padding: 7px 12px;
  border-radius: 8px;
  text-decoration: none;
  font-size: 13px;
  cursor: pointer;
  transition: background .15s, border-color .15s, color .15s;
}
.btn:hover { background: var(--accent); border-color: var(--primary); }
.btn.primary { background: var(--primary); color: #fff; border-color: var(--primary); }
.btn.primary:hover { background: var(--primary-dark); }

.lang-select {
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  padding: 7px 10px;
  border-radius: 8px;
  font-size: 13px;
  cursor: pointer;
}

/* ---------- Layout ---------- */
.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 26px 18px 60px;
}
.hero {
  background: linear-gradient(135deg, #0b6bcb 0%, #09529e 100%);
  color: #fff;
  border-radius: var(--radius);
  padding: 30px 28px;
  box-shadow: var(--shadow);
  margin-bottom: 26px;
}
.hero h1 { margin: 0 0 8px; font-size: 26px; }
.hero p { margin: 0; opacity: .92; font-size: 14px; }

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 18px;
}
.module-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--shadow);
  text-decoration: none;
  color: var(--text);
  transition: transform .15s, box-shadow .15s, border-color .15s;
  display: block;
}
.module-card:hover {
  transform: translateY(-3px);
  border-color: var(--primary);
  box-shadow: 0 4px 10px rgba(20,40,70,.12), 0 14px 30px rgba(20,40,70,.10);
}
.module-card h3 { margin: 0 0 8px; font-size: 18px; color: var(--primary-dark); }
.module-card .ico {
  width: 42px; height: 42px; border-radius: 10px;
  background: var(--accent); color: var(--primary);
  display: flex; align-items: center; justify-content: center;
  font-size: 22px; margin-bottom: 14px;
}
.module-card p { margin: 0; color: var(--muted); font-size: 13.5px; }

.section-title { font-size: 18px; margin: 34px 0 14px; }

/* ---------- Calculator ---------- */
.calc-wrap {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 22px;
}
@media (max-width: 820px) { .calc-wrap { grid-template-columns: 1fr; } }

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--shadow);
}
.panel h2 { margin: 0 0 4px; font-size: 19px; color: var(--primary-dark); }
.panel .sub { color: var(--muted); font-size: 13px; margin: 0 0 18px; }

.field { margin-bottom: 14px; }
.field label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 5px;
  color: var(--text);
}
.field .hint { font-weight: 400; color: var(--muted); font-size: 11.5px; }
.field input, .field select {
  width: 100%;
  padding: 9px 11px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  color: var(--text);
  background: #fff;
}
.field input:focus, .field select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(11,107,203,.15);
}
.field-row { display: flex; gap: 10px; }
.field-row > div { flex: 1; }

.preset-row { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 18px; }
.preset-btn {
  font-size: 12px;
  padding: 6px 10px;
  border: 1px solid var(--border);
  background: var(--accent);
  border-radius: 7px;
  cursor: pointer;
  color: var(--primary-dark);
}
.preset-btn:hover { border-color: var(--primary); }

.results .result-item {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding: 10px 0;
  border-bottom: 1px dashed var(--border);
}
.results .result-item:last-child { border-bottom: none; }
.results .r-label { font-size: 13.5px; color: var(--muted); }
.results .r-value {
  font-size: 17px;
  font-weight: 700;
  color: var(--text);
  font-variant-numeric: tabular-nums;
}
.results .r-value span.unit { font-size: 12px; font-weight: 400; color: var(--muted); margin-left: 4px; }
.results .r-group-title {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: .5px;
  color: var(--primary);
  margin: 18px 0 4px;
  font-weight: 700;
}

.note {
  background: var(--accent);
  border-left: 3px solid var(--primary);
  padding: 12px 14px;
  border-radius: 6px;
  font-size: 12.5px;
  color: var(--muted);
  margin-top: 16px;
}

footer.foot {
  text-align: center;
  color: var(--muted);
  font-size: 12px;
  padding: 24px 0 10px;
}

.badge {
  display: inline-block;
  font-size: 11px;
  background: var(--ok);
  color: #fff;
  padding: 2px 8px;
  border-radius: 20px;
  margin-left: 6px;
  vertical-align: middle;
}

/* Export toolbar */
.export-bar {
  display: flex;
  gap: 10px;
  margin: 0 0 16px;
}
.btn-export {
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 8px 14px;
  font-size: 13px;
  cursor: pointer;
  transition: background .15s;
}
.btn-export:hover { background: var(--primary-dark); }

/* Print report header: hidden on screen, shown only in print/PDF */
.print-header { display: none; }
.print-header .ph-title { font-size: 18px; font-weight: 700; margin: 0 0 4px; }
.print-header .ph-sub { font-size: 12px; color: var(--muted); margin: 0 0 10px; }
.print-header table { width: 100%; border-collapse: collapse; font-size: 12px; margin-bottom: 12px; }
.print-header td { padding: 3px 8px; border: 1px solid #ddd; }
.print-header td.ph-k { font-weight: 600; background: #f6f8fa; width: 38%; }

/* Print / PDF: keep only the results panel + report header */
@media print {
  .topbar, .container > .panel:first-child, .export-bar, footer.foot { display: none !important; }
  body { background: #fff; }
  .container { display: block; }
  .panel.results { box-shadow: none; border: 1px solid #ccc; }
  .print-header { display: block !important; margin-bottom: 16px; }
}

/* Comparison table */
.cmp-table {
  width: 100%;
  border-collapse: collapse;
  margin: 6px 0 14px;
  font-size: 14px;
}
.cmp-table th, .cmp-table td {
  border: 1px solid var(--border);
  padding: 9px 12px;
  text-align: left;
}
.cmp-table thead th {
  background: var(--accent);
  color: var(--primary-dark);
  font-weight: 600;
}
.cmp-table tbody tr:nth-child(even) { background: #fafcff; }
.cmp-table td:first-child { font-weight: 500; color: var(--muted); }

/* ---------- Window winding visualization (autotransformer) ---------- */
.window-viz {
  margin: 14px 0 6px;
  padding: 12px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: #fbfdff;
}
.window-viz .wv-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--muted);
  margin-bottom: 8px;
}
.window-viz svg { display: block; max-width: 280px; margin: 0 auto; }
.window-viz .wv-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  justify-content: center;
  margin-top: 8px;
  font-size: 12.5px;
  color: var(--muted);
}
.window-viz .wv-swatch {
  display: inline-block;
  width: 12px;
  height: 12px;
  border-radius: 3px;
  margin-right: 5px;
  vertical-align: -1px;
}
.window-viz .wv-swatch.c { background: #2f80ed; }
.window-viz .wv-swatch.s { background: #eb5757; }
@media print {
  .window-viz { background: #fff; }
}