/* =========================================================
   CalculatePilot — Design System
   Clean, minimal, instrument-precise. Teal signal on paper.
   ========================================================= */

@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@500;600;700&family=Inter:wght@400;500;600;700&family=IBM+Plex+Mono:wght@500;600&display=swap');

:root {
  /* Color tokens */
  --paper: #FBFBFA;
  --paper-raised: #FFFFFF;
  --ink: #14171A;
  --slate: #6B7280;
  --slate-light: #9CA3AF;
  --line: #E5E7EB;
  --line-soft: #EFF1F3;
  --signal: #0F6B5C;
  --signal-dark: #0B5347;
  --signal-soft: #EAF4F1;
  --signal-soft-hover: #DCEEE8;
  --danger: #B3261E;

  /* Type */
  --font-display: 'Space Grotesk', sans-serif;
  --font-body: 'Inter', sans-serif;
  --font-mono: 'IBM Plex Mono', monospace;

  /* Scale */
  --radius: 10px;
  --radius-sm: 6px;
  --shadow-card: 0 1px 2px rgba(20,23,26,0.04), 0 1px 12px rgba(20,23,26,0.04);
  --shadow-raised: 0 2px 4px rgba(20,23,26,0.06), 0 8px 24px rgba(20,23,26,0.06);
  --container: 1120px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.15;
  margin: 0 0 0.5em;
  letter-spacing: -0.01em;
}

h1 { font-size: clamp(1.9rem, 4vw, 2.6rem); }
h2 { font-size: clamp(1.4rem, 2.6vw, 1.8rem); }
h3 { font-size: 1.15rem; }

p { margin: 0 0 1em; color: var(--ink); }
p.lede { color: var(--slate); font-size: 1.05rem; }

a { color: var(--signal); text-decoration: none; }
a:hover { text-decoration: underline; }

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

/* Focus visibility */
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible {
  outline: 2px solid var(--signal);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
}

/* ---------- Header ---------- */
.site-header {
  border-bottom: 1px solid var(--line);
  background: var(--paper-raised);
  position: sticky;
  top: 0;
  z-index: 40;
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.logo {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--ink);
  display: flex;
  align-items: center;
  gap: 8px;
}
.logo .dot { color: var(--signal); }
.nav-links {
  display: flex;
  gap: 28px;
  list-style: none;
  margin: 0; padding: 0;
}
.nav-links a {
  color: var(--ink);
  font-weight: 500;
  font-size: 0.94rem;
}
.nav-links a:hover { color: var(--signal); text-decoration: none; }
.nav-toggle { display: none; }

@media (max-width: 720px) {
  .nav-links { display: none; }
  .nav-toggle {
    display: block;
    background: none; border: 1px solid var(--line);
    border-radius: var(--radius-sm);
    padding: 8px 12px; font-family: var(--font-body);
  }
}

/* ---------- Breadcrumb ---------- */
.breadcrumb {
  font-size: 0.85rem;
  color: var(--slate);
  margin: 20px 0 8px;
}
.breadcrumb a { color: var(--slate); }
.breadcrumb a:hover { color: var(--signal); }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.95rem;
  padding: 11px 20px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: background .15s ease, border-color .15s ease, transform .1s ease;
}
.btn-primary {
  background: var(--signal);
  color: #fff;
}
.btn-primary:hover { background: var(--signal-dark); text-decoration: none; }
.btn-primary:active { transform: translateY(1px); }
.btn-ghost {
  background: transparent;
  border-color: var(--line);
  color: var(--ink);
}
.btn-ghost:hover { border-color: var(--signal); color: var(--signal); text-decoration: none; }

/* ---------- Hero ---------- */
.hero {
  padding: 64px 0 48px;
  border-bottom: 1px solid var(--line);
}
.hero .eyebrow {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--signal);
  margin-bottom: 14px;
}
.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
}
@media (max-width: 860px) {
  .hero-grid { grid-template-columns: 1fr; }
}

/* Mini readout preview on homepage hero */
.mini-readout {
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-raised);
  overflow: hidden;
}
.mini-readout .bar { height: 4px; background: var(--signal); }
.mini-readout-body { padding: 22px; }
.mini-readout-label { font-size: 0.82rem; color: var(--slate); margin-bottom: 6px; }
.mini-readout-value {
  font-family: var(--font-mono);
  font-size: 2.1rem;
  font-weight: 600;
  color: var(--ink);
  font-variant-numeric: tabular-nums;
}
.mini-readout-sub { font-size: 0.85rem; color: var(--slate-light); margin-top: 6px; }

/* ---------- Search bar ---------- */
.search-bar {
  display: flex;
  gap: 8px;
  margin-top: 24px;
}
.search-bar input {
  flex: 1;
  padding: 13px 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  font-family: var(--font-body);
  font-size: 0.95rem;
  background: var(--paper-raised);
}
.search-bar input:focus { border-color: var(--signal); }

/* ---------- Category grid ---------- */
.section { padding: 56px 0; }
.section-head { display: flex; align-items: baseline; justify-content: space-between; margin-bottom: 24px; }
.section-head a { font-size: 0.9rem; font-weight: 600; }

.cat-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}
@media (max-width: 900px) { .cat-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 520px) { .cat-grid { grid-template-columns: 1fr; } }

.cat-card {
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
  transition: border-color .15s ease, box-shadow .15s ease, transform .12s ease;
}
.cat-card:hover { border-color: var(--signal); box-shadow: var(--shadow-card); transform: translateY(-2px); text-decoration: none; }
.cat-card .n { font-family: var(--font-mono); font-size: 0.78rem; color: var(--signal); margin-bottom: 10px; }
.cat-card h3 { margin-bottom: 6px; color: var(--ink); }
.cat-card p { color: var(--slate); font-size: 0.88rem; margin: 0; }

/* Tool list (popular tools grid) */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}
@media (max-width: 860px) { .tool-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .tool-grid { grid-template-columns: 1fr; } }

.tool-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--paper-raised);
  color: var(--ink);
  font-weight: 500;
  font-size: 0.92rem;
}
.tool-link:hover { border-color: var(--signal); color: var(--signal); text-decoration: none; }
.tool-link .arrow { color: var(--slate-light); }
.tool-link:hover .arrow { color: var(--signal); }

/* ---------- Calculator layout ---------- */
.calc-page-head { padding: 32px 0 8px; }
.calc-layout {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 32px;
  align-items: flex-start;
  padding: 24px 0 8px;
}
@media (max-width: 900px) {
  .calc-layout { grid-template-columns: 1fr; }
}

.calc-card {
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow-card);
}

.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-bottom: 16px; }
@media (max-width: 520px) { .field-row { grid-template-columns: 1fr; } }

.field { display: flex; flex-direction: column; gap: 6px; margin-bottom: 16px; }
.field label { font-size: 0.85rem; font-weight: 600; color: var(--ink); }
.field .hint { font-size: 0.78rem; color: var(--slate-light); }
.field input, .field select {
  padding: 11px 13px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.98rem;
  background: var(--paper);
  color: var(--ink);
}
.field input:focus, .field select:focus { border-color: var(--signal); background: var(--paper-raised); }

.calc-actions { display: flex; gap: 10px; margin-top: 8px; }

/* Sticky result readout */
.readout {
  position: sticky;
  top: 84px;
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-raised);
  overflow: hidden;
}
.readout .bar { height: 4px; background: var(--signal); }
.readout-body { padding: 26px; }
.readout-label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--slate);
  margin-bottom: 10px;
}
.readout-value {
  font-family: var(--font-mono);
  font-size: 2.4rem;
  font-weight: 600;
  color: var(--signal-dark);
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
}
.readout-value.big { color: var(--signal); }
.readout-breakdown {
  margin-top: 20px;
  border-top: 1px solid var(--line-soft);
  padding-top: 16px;
}
.readout-row {
  display: flex;
  justify-content: space-between;
  padding: 7px 0;
  font-size: 0.88rem;
}
.readout-row span:first-child { color: var(--slate); }
.readout-row span:last-child {
  font-family: var(--font-mono);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

/* ---------- Content / SEO body ---------- */
.content-block { padding: 40px 0; border-top: 1px solid var(--line); }
.content-block h2 { margin-top: 0.2em; }
.content-block .prose { max-width: 760px; }
.formula-box {
  background: var(--signal-soft);
  border: 1px solid var(--signal-soft-hover);
  border-radius: var(--radius);
  padding: 20px 24px;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--signal-dark);
  margin: 20px 0;
  overflow-x: auto;
}

.faq-item {
  border-bottom: 1px solid var(--line);
  padding: 18px 0;
}
.faq-item h3 { font-size: 1rem; margin-bottom: 8px; }
.faq-item p { color: var(--slate); margin: 0; font-size: 0.94rem; }

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 48px 0 32px;
  margin-top: 40px;
  background: var(--paper-raised);
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr repeat(4, 1fr);
  gap: 24px;
}
@media (max-width: 860px) { .footer-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 520px) { .footer-grid { grid-template-columns: 1fr; } }
.footer-grid h4 { font-size: 0.82rem; color: var(--slate); text-transform: uppercase; letter-spacing: 0.04em; margin-bottom: 12px; }
.footer-grid ul { list-style: none; margin: 0; padding: 0; }
.footer-grid li { margin-bottom: 9px; }
.footer-grid a { color: var(--ink); font-size: 0.9rem; }
.footer-grid a:hover { color: var(--signal); }
.footer-bottom {
  margin-top: 36px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  font-size: 0.82rem;
  color: var(--slate-light);
}
@media (max-width: 520px) { .footer-bottom { flex-direction: column; gap: 8px; } }