:root {
  --bg: #f7f8fa;
  --card: #ffffff;
  --ink: #1f2733;
  --muted: #64748b;
  --line: #e4e8ee;
  --brand: #2563eb;
  --brand-soft: #eff4ff;
  --accent: #16a34a;
  --warn: #b45309;
  --radius: 14px;
  --maxw: 920px;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.6;
  font-size: 16px;
}
a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }

.tool-header {
  background: var(--card);
  border-bottom: 1px solid var(--line);
  padding: 14px 0;
}
.tool-header .inner, .tool-main, .tool-footer .inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 18px;
}
.tool-header .brand {
  font-weight: 800;
  font-size: 18px;
  letter-spacing: -0.3px;
}
.tool-header .brand span { color: var(--brand); }
.tool-header nav { float: right; font-size: 14px; color: var(--muted); }
.tool-header::after { content: ""; display: block; clear: both; }

.tool-main { padding: 28px 18px 60px; }
h1 { font-size: 30px; line-height: 1.2; letter-spacing: -0.5px; margin: 0 0 14px; }
h2 { font-size: 22px; margin: 34px 0 12px; letter-spacing: -0.3px; }
h3 { font-size: 18px; margin: 22px 0 8px; }

.answer-box {
  background: var(--brand-soft);
  border: 1px solid #d6e3ff;
  border-left: 4px solid var(--brand);
  border-radius: var(--radius);
  padding: 16px 18px;
  margin: 0 0 24px;
  font-size: 17px;
}
.answer-box strong { color: var(--brand); }

.calculator {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: 0 1px 3px rgba(16,24,40,0.04);
}
.calc-group-title {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  color: var(--muted);
  font-weight: 700;
  margin: 18px 0 8px;
}
.calc-group-title:first-child { margin-top: 0; }
.input-row {
  display: grid;
  grid-template-columns: 1fr 200px;
  gap: 12px;
  align-items: center;
  margin-bottom: 12px;
}
.input-row label { font-size: 15px; font-weight: 500; }
.input-row .field { position: relative; }
.input-row input[type="number"],
.input-row select {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  font-size: 15px;
  background: #fff;
  color: var(--ink);
}
.input-row input[type="range"] { width: 100%; }
.input-row .unit {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--muted);
  font-size: 13px;
  pointer-events: none;
}
.range-val {
  display: inline-block;
  margin-left: 8px;
  font-weight: 700;
  color: var(--brand);
}

.result-section {
  margin-top: 22px;
  border-top: 1px dashed var(--line);
  padding-top: 18px;
}
.result-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 12px;
}
.result-card {
  background: #f1f5fb;
  border: 1px solid #e1e9f5;
  border-radius: 12px;
  padding: 14px;
}
.result-card .rl { font-size: 13px; color: var(--muted); margin-bottom: 4px; }
.result-card .rv { font-size: 22px; font-weight: 800; color: var(--ink); letter-spacing: -0.5px; }
.result-card.hl { background: var(--brand); border-color: var(--brand); }
.result-card.hl .rl { color: #dbe7ff; }
.result-card.hl .rv { color: #fff; }

.chart-wrap {
  margin-top: 22px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
}
.chart-wrap h3 { margin-top: 0; }
.chart-wrap canvas { max-width: 100%; }

.tool-type-badge {
  display: inline-block;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 3px 10px;
  border-radius: 999px;
  margin-bottom: 10px;
}
.badge-reverse { background: #fef3c7; color: #92400e; }
.badge-compare { background: #dbeafe; color: #1e40af; }
.badge-sim { background: #dcfce7; color: #166534; }

.faq details {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 4px 16px;
  margin-bottom: 10px;
}
.faq summary {
  cursor: pointer;
  font-weight: 600;
  padding: 12px 0;
  list-style: none;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::before { content: "▸ "; color: var(--brand); }
.faq details[open] summary::before { content: "▾ "; }
.faq p { margin: 0 0 12px; color: #334155; }

.related-tools {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
  margin-top: 10px;
}
.related-tools a {
  display: block;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 14px;
  color: var(--ink);
  font-weight: 600;
}
.related-tools a:hover { border-color: var(--brand); text-decoration: none; }

.seo-content {
  margin-top: 24px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 4px 16px;
}
.seo-content summary { cursor: pointer; font-weight: 600; padding: 12px 0; }

.ad-slot {
  margin: 22px 0;
  text-align: center;
}
.ad-label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--muted);
  margin-bottom: 6px;
}

.tool-footer {
  border-top: 1px solid var(--line);
  background: #fff;
  padding: 22px 0;
  color: var(--muted);
  font-size: 13px;
}
.disclaimer {
  background: #fffbeb;
  border: 1px solid #fde68a;
  border-radius: 10px;
  padding: 12px 14px;
  font-size: 13px;
  color: #7c5e10;
  margin: 18px 0;
}

@media (max-width: 640px) {
  h1 { font-size: 24px; }
  .input-row { grid-template-columns: 1fr; }
  .input-row .field { max-width: 100%; }
}