:root{
  --ink: #1B2A4A;
  --ink-light: #2F4470;
  --paper: #FAFAF7;
  --paper-dim: #EFEEE7;
  --graphite: #3D3D3A;
  --graphite-soft: #6B6A63;
  --orange: #D85A30;
  --orange-soft: #FBE9E2;
  --line: #D8D6CB;
  --white: #FFFFFF;
  --success-bg: #EAF3E8;
}

*{ margin:0; padding:0; box-sizing:border-box; }

html{ scroll-behavior: smooth; }

body{
  background: var(--paper);
  color: var(--graphite);
  font-family: 'Inter', -apple-system, sans-serif;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

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

a{ color: var(--ink); text-decoration: underline; text-decoration-color: var(--line); text-underline-offset: 2px; }
a:hover{ text-decoration-color: var(--ink); }

.wrap{ max-width: 1080px; margin: 0 auto; padding: 0 24px; }

/* ===== HEADER ===== */
header.site{
  background: var(--ink);
  color: var(--paper);
  padding: 16px 0;
  border-bottom: 3px solid var(--orange);
}
header.site .wrap{ display:flex; align-items:center; justify-content:space-between; flex-wrap: wrap; gap: 10px; }
.logo{
  font-family: 'JetBrains Mono', monospace;
  font-weight: 600;
  font-size: 15px;
  letter-spacing: 0.02em;
  display:flex;
  align-items:center;
  gap: 8px;
  color: var(--paper);
  text-decoration: none;
}
.logo .mark{
  width: 18px; height: 18px;
  border: 2px solid var(--orange);
  border-radius: 3px;
  display:inline-block;
  position:relative;
}
.logo .mark::after{
  content:'';
  position:absolute;
  inset: 3px;
  border-radius: 50%;
  border: 1.5px solid var(--orange);
}
nav.site-nav{
  display:flex;
  gap: 22px;
  font-size: 13.5px;
  flex-wrap: wrap;
}
nav.site-nav a{ color: var(--paper); opacity: 0.78; text-decoration: none; }
nav.site-nav a:hover, nav.site-nav a.current{ opacity: 1; }
nav.site-nav a.current{ border-bottom: 2px solid var(--orange); padding-bottom: 2px; }

/* ===== SHARED INTRO / EYEBROW ===== */
.intro{ padding: 38px 0 8px; }
.eyebrow{
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--orange);
  font-weight: 600;
}
h1{
  font-size: 32px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin: 8px 0 10px;
}
.intro p.lede{
  font-size: 16px;
  color: var(--graphite-soft);
  max-width: 640px;
}

/* ===== TOOL FRAME (shared by all calculators) ===== */
.tool{
  margin: 28px 0 48px;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 14px;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(27,42,74,0.06);
}

.mode-strip{
  background: var(--paper-dim);
  border-bottom: 1px solid var(--line);
  padding: 14px 20px;
  display:flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
}
.mode-strip .mode-label{
  font-family: 'JetBrains Mono', monospace;
  font-size: 11.5px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--graphite-soft);
  margin-right: 6px;
}
.mode-btn{
  font-family: 'Inter', sans-serif;
  font-size: 13.5px;
  font-weight: 500;
  padding: 8px 14px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--white);
  color: var(--graphite);
  cursor: pointer;
  transition: all 0.15s ease;
}
.mode-btn:hover{ border-color: var(--ink-light); }
.mode-btn.active{
  background: var(--ink);
  border-color: var(--ink);
  color: var(--white);
}
.mode-btn:focus-visible{ outline: 2px solid var(--orange); outline-offset: 2px; }

.tool-body{
  display: grid;
  grid-template-columns: 1fr 1.15fr;
  gap: 0;
}
@media (max-width: 760px){
  .tool-body{ grid-template-columns: 1fr; }
}

.diagram-stage{
  background: var(--paper);
  border-right: 1px solid var(--line);
  padding: 30px 24px;
  display:flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}
.diagram-stage svg{ width: 100%; max-width: 280px; height: auto; }
.unit-row{
  display:flex;
  gap: 6px;
  margin-top: 18px;
  flex-wrap: wrap;
  justify-content: center;
}
.unit-btn{
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  padding: 6px 11px;
  border-radius: 7px;
  border: 1px solid var(--line);
  background: var(--white);
  color: var(--graphite-soft);
  cursor: pointer;
  transition: all 0.15s ease;
}
.unit-btn:hover{ border-color: var(--ink-light); color: var(--graphite); }
.unit-btn.active{ background: var(--ink); border-color: var(--ink); color: var(--white); }
.unit-btn:focus-visible{ outline: 2px solid var(--orange); outline-offset: 2px; }

.input-panel{ padding: 30px 28px; display:flex; flex-direction:column; gap: 20px; }

.field-group{ display:flex; flex-direction: column; gap: 6px; }
.field-group label{
  font-size: 13.5px;
  font-weight: 500;
  color: var(--graphite);
  display:flex;
  justify-content: space-between;
  align-items: baseline;
}
.field-group label .var{
  font-family: 'JetBrains Mono', monospace;
  color: var(--graphite-soft);
  font-size: 12px;
}
.field-group input[type="number"], .field-group select{
  font-family: 'JetBrains Mono', monospace;
  font-size: 16px;
  padding: 11px 13px;
  border: 1.5px solid var(--line);
  border-radius: 9px;
  background: var(--paper);
  color: var(--ink);
  width: 100%;
}
.field-group input[type="number"]:focus, .field-group select:focus{
  outline: none;
  border-color: var(--orange);
  background: var(--white);
}
.field-group input[type="number"]:disabled{
  background: var(--paper-dim);
  color: var(--graphite-soft);
  border-style: dashed;
}
.field-hint{
  font-size: 12px;
  color: var(--graphite-soft);
}
.field-hint.solving{
  color: var(--orange);
  font-weight: 500;
}

hr.div{ border: none; border-top: 1px solid var(--line); margin: 4px 0; }

.results{
  background: var(--paper-dim);
  border-radius: 10px;
  padding: 18px 20px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.result-row{
  display:flex;
  justify-content: space-between;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 6px;
}
.result-row .r-label{
  font-size: 13.5px;
  color: var(--graphite-soft);
  font-weight: 500;
}
.result-row .r-value{
  font-family: 'JetBrains Mono', monospace;
  font-size: 19px;
  font-weight: 600;
  color: var(--ink);
}
.result-row .r-value .u{
  font-size: 13px;
  color: var(--graphite-soft);
  font-weight: 500;
  margin-left: 4px;
}
.result-row.primary .r-value{ font-size: 26px; color: var(--orange); }
.result-row.primary .r-label{ font-weight: 600; color: var(--ink); }

.convert-strip{
  display:flex;
  gap: 14px;
  flex-wrap: wrap;
  font-family: 'JetBrains Mono', monospace;
  font-size: 12.5px;
  color: var(--graphite-soft);
  padding-top: 8px;
  border-top: 1px dashed var(--line);
}
.convert-strip b{ color: var(--graphite); }

.formula-note{
  font-size: 12.5px;
  color: var(--graphite-soft);
  line-height: 1.6;
}
.formula-note code{
  font-family: 'JetBrains Mono', monospace;
  background: var(--white);
  padding: 1px 6px;
  border-radius: 5px;
  color: var(--ink);
  border: 1px solid var(--line);
}

.error-msg{
  background: #FBE9E2;
  border: 1px solid var(--orange);
  color: #8C3A1F;
  font-size: 13px;
  padding: 10px 14px;
  border-radius: 8px;
  display: none;
}
.error-msg.show{ display: block; }

.sa-breakdown{
  display: none;
  gap: 10px;
  flex-wrap: wrap;
}
.sa-breakdown.show{ display:flex; }
.sa-chip{
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 8px 12px;
  font-size: 12.5px;
  flex: 1;
  min-width: 130px;
}
.sa-chip .chip-label{ color: var(--graphite-soft); display:block; margin-bottom: 2px; }
.sa-chip .chip-value{ font-family: 'JetBrains Mono', monospace; font-weight: 600; color: var(--ink); }

/* ===== CONTENT SECTIONS (SEO / blog) ===== */
.content-section{ padding: 36px 0; border-top: 1px solid var(--line); }
.content-section h2{
  font-size: 23px;
  font-weight: 700;
  color: var(--ink);
  letter-spacing: -0.01em;
  margin-bottom: 14px;
}
.content-section h3{
  font-size: 17px;
  font-weight: 600;
  color: var(--ink);
  margin: 22px 0 8px;
}
.content-section p{
  font-size: 15px;
  color: var(--graphite);
  margin-bottom: 12px;
  max-width: 720px;
}
.content-section ul, .content-section ol{
  margin: 0 0 14px 20px;
  font-size: 15px;
  color: var(--graphite);
  max-width: 700px;
}
.content-section li{ margin-bottom: 6px; }

.formula-block{
  background: var(--paper-dim);
  border-left: 3px solid var(--orange);
  border-radius: 0 8px 8px 0;
  padding: 14px 18px;
  margin: 14px 0;
  font-family: 'JetBrains Mono', monospace;
  font-size: 15px;
  color: var(--ink);
}

.example-box{
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 16px 20px;
  margin: 14px 0;
  max-width: 700px;
}
.example-box .ex-title{
  font-weight: 600;
  font-size: 13.5px;
  color: var(--orange);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 8px;
}

table.calc-table{
  border-collapse: collapse;
  margin: 14px 0;
  font-size: 14px;
  max-width: 700px;
  width: 100%;
}
table.calc-table th, table.calc-table td{
  border: 1px solid var(--line);
  padding: 8px 12px;
  text-align: left;
}
table.calc-table th{
  background: var(--paper-dim);
  font-weight: 600;
  color: var(--ink);
}
table.calc-table td{ font-family: 'JetBrains Mono', monospace; font-size: 13.5px; }

code.inline{
  font-family: 'JetBrains Mono', monospace;
  background: var(--paper-dim);
  padding: 1px 6px;
  border-radius: 5px;
  color: var(--ink);
}

/* FAQ accordion */
.faq-item{ border-bottom: 1px solid var(--line); }
.faq-q{
  width: 100%;
  text-align: left;
  background: none;
  border: none;
  padding: 16px 0;
  font-size: 15.5px;
  font-weight: 600;
  color: var(--ink);
  cursor: pointer;
  display:flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}
.faq-q:focus-visible{ outline: 2px solid var(--orange); outline-offset: 2px; }
.faq-q .chevron{
  font-family: 'JetBrains Mono', monospace;
  color: var(--orange);
  font-size: 14px;
  transition: transform 0.2s ease;
  flex-shrink: 0;
}
.faq-q[aria-expanded="true"] .chevron{ transform: rotate(45deg); }
.faq-a{ max-height: 0; overflow: hidden; transition: max-height 0.25s ease; }
.faq-a-inner{
  padding: 0 0 18px;
  font-size: 14.5px;
  color: var(--graphite-soft);
  max-width: 680px;
}

/* ===== CARD GRIDS (homepage tool cards, related tools) ===== */
.card-grid{
  display:grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-top: 16px;
}
@media (max-width: 700px){ .card-grid{ grid-template-columns: 1fr; } }

.tool-card{
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 20px 20px;
  background: var(--white);
  text-decoration: none;
  display:block;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.tool-card:hover{ border-color: var(--orange); box-shadow: 0 4px 14px rgba(27,42,74,0.08); }
.tool-card .tc-eyebrow{
  font-family: 'JetBrains Mono', monospace;
  font-size: 10.5px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--orange);
  font-weight: 600;
  display: block;
  margin-bottom: 6px;
}
.tool-card .tc-title{ font-weight: 700; color: var(--ink); font-size: 16.5px; margin-bottom: 6px; }
.tool-card .tc-desc{ font-size: 13.5px; color: var(--graphite-soft); line-height: 1.5; }

.related-card{
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 16px 18px;
  background: var(--white);
  text-decoration: none;
  display: block;
}
.related-card:hover{ border-color: var(--orange); }
.related-card .rc-title{ font-weight: 600; color: var(--ink); font-size: 14.5px; margin-bottom: 4px; }
.related-card .rc-desc{ font-size: 13px; color: var(--graphite-soft); }

/* ===== BLOG-SPECIFIC ===== */
.blog-meta{
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  color: var(--graphite-soft);
  margin-bottom: 6px;
}
.blog-cta{
  background: var(--paper-dim);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 18px 20px;
  margin: 24px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.blog-cta .bc-text{ font-size: 14.5px; color: var(--graphite); }
.blog-cta .bc-text strong{ color: var(--ink); }
.btn-primary{
  background: var(--orange);
  color: var(--white) !important;
  text-decoration: none;
  font-weight: 600;
  font-size: 13.5px;
  padding: 10px 18px;
  border-radius: 8px;
  white-space: nowrap;
}
.btn-primary:hover{ background: #BD4B26; }

footer.site{
  background: var(--ink);
  color: var(--paper);
  padding: 28px 0;
  margin-top: 30px;
}
footer.site .wrap{
  display:flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 12.5px;
  opacity: 0.7;
}
footer.site a{ color: var(--paper); }

.skip-link{ position: absolute; left: -9999px; }
.skip-link:focus{
  left: 16px;
  top: 16px;
  background: var(--orange);
  color: var(--white);
  padding: 8px 14px;
  border-radius: 6px;
  z-index: 100;
}