/* =========================================================
   A1C Calculator — Design tokens
   Palette: paper #F3F5F3 / ink #12263A / teal #176D63
            amber #DC9C2B / coral #C1503E / slate #56646C
   Type: Space Grotesk (display) / IBM Plex Sans (body) / IBM Plex Mono (data)
   ========================================================= */

:root{
  --paper: #F3F5F3;
  --paper-alt: #E9EDEA;
  --ink: #12263A;
  --ink-soft: #2C4256;
  --teal: #176D63;
  --teal-dark: #0E3C36;
  --amber: #B97A1E;
  --coral: #B84936;
  --slate: #5B6B76;
  --line: rgba(18,38,58,0.14);

  --zone-normal: #1E8F72;
  --zone-pre: #C68A24;
  --zone-high: #B84936;

  --font-display: 'Space Grotesk', sans-serif;
  --font-body: 'IBM Plex Sans', sans-serif;
  --font-mono: 'IBM Plex Mono', monospace;

  --radius: 4px;
  --container: 1120px;
}

*, *::before, *::after{ box-sizing: border-box; }

@media (prefers-reduced-motion: reduce){
  *{ animation-duration: 0.001ms !important; transition-duration: 0.001ms !important; }
}

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{
  font-family: var(--font-display);
  color: var(--ink);
  line-height: 1.15;
  margin: 0 0 0.5em;
  letter-spacing: -0.01em;
}

h1{ font-size: clamp(2rem, 5vw, 3.2rem); font-weight: 700; }
h2{ font-size: clamp(1.5rem, 3vw, 2.1rem); font-weight: 600; }

p{ margin: 0 0 1em; color: var(--ink-soft); }

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

.skip-link a{
  position:absolute; left:-999px; top:0; background:var(--ink); color:#fff;
  padding: 10px 16px; z-index: 200; border-radius: 0 0 6px 0;
}
.skip-link a:focus{ left:0; }

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

button{ font-family: inherit; cursor: pointer; }

/* =========================== HEADER =========================== */
.site-header{
  position: sticky; top:0; z-index: 100;
  background: rgba(243,245,243,0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.header-inner{
  max-width: var(--container);
  margin: 0 auto;
  padding: 14px 24px;
  display:flex; align-items:center; justify-content: space-between;
}
.brand{
  display:flex; align-items:center; gap:8px;
  text-decoration:none; color: var(--ink);
  font-family: var(--font-display); font-weight:700; font-size:1.25rem;
}
.brand-mark{ color: var(--teal); display:flex; }
.brand-text em{ font-style: normal; color: var(--teal); }

.main-nav{ display:flex; gap: 28px; }
.main-nav a{
  color: var(--ink-soft); text-decoration:none; font-size: 0.95rem; font-weight:500;
  padding: 6px 2px; border-bottom: 2px solid transparent;
}
.main-nav a:hover, .main-nav a:focus-visible{ color: var(--teal); border-bottom-color: var(--teal); }

.nav-toggle{
  display:none; flex-direction:column; justify-content:center; gap:5px;
  width:38px; height:38px; background:none; border:1px solid var(--line); border-radius:6px;
}
.nav-toggle span{ display:block; height:2px; width:18px; background: var(--ink); margin:0 auto; }

/* =========================== HERO =========================== */
.hero{ padding: 64px 0 40px; }
.hero-inner{ max-width: var(--container); margin:0 auto; padding: 0 24px; }
.hero-copy{ max-width: 720px; }
.eyebrow{
  font-family: var(--font-mono); font-size: 0.8rem; letter-spacing: 0.06em;
  text-transform: uppercase; color: var(--teal); margin-bottom: 14px;
}
.hero-sub{ font-size: 1.1rem; max-width: 60ch; }
.hero-actions{ display:flex; gap: 14px; flex-wrap: wrap; margin-top: 24px; }

.btn{
  display:inline-flex; align-items:center; justify-content:center;
  padding: 13px 26px; border-radius: var(--radius); font-weight:600; text-decoration:none;
  font-size: 0.98rem; border: 1px solid transparent; transition: transform .15s ease, background .15s ease;
}
.btn:hover{ transform: translateY(-1px); }
.btn-primary{ background: var(--teal); color:#fff; }
.btn-primary:hover{ background: var(--teal-dark); }
.btn-ghost{ border-color: var(--line); color: var(--ink); background: transparent; }
.btn-ghost:hover{ border-color: var(--teal); color: var(--teal); }

/* =========================== CALCULATOR SLIP =========================== */
.calc-section{ padding: 20px 0 72px; }
.calc-section .section-inner{
  display:grid; grid-template-columns: minmax(0,1.15fr) minmax(0,0.85fr); gap: 48px; align-items:start;
}
.calc-section.alt{ background: var(--paper-alt); padding: 56px 0 72px; }
.reverse-layout{ grid-template-columns: minmax(0,0.85fr) minmax(0,1.15fr); }
.reverse-layout .slip-card{ order:2; }
.reverse-layout .calc-aside{ order:1; }

.slip-card{
  background:#fff; border: 1px solid var(--line); border-radius: 10px;
  position: relative; overflow: hidden;
  box-shadow: 0 20px 40px -28px rgba(18,38,58,0.35);
}
.slip-perf{
  height: 12px;
  background-image: radial-gradient(circle, var(--paper) 3px, transparent 3.5px);
  background-size: 18px 12px;
  background-position: center;
  border-bottom: 1px dashed var(--line);
}
.slip-head{
  display:flex; justify-content: space-between; align-items:center;
  padding: 18px 26px 0;
  font-family: var(--font-mono); font-size: 0.78rem; letter-spacing: 0.05em; text-transform: uppercase;
  color: var(--slate);
}
.slip-id{ color: var(--teal); font-weight:600; }
.slip-body{ padding: 18px 26px 8px; }
.slip-foot{
  border-top: 1px solid var(--line); padding: 12px 26px; font-family: var(--font-mono);
  font-size: 0.76rem; color: var(--slate);
}

.field-row label{
  display:block; font-weight:600; font-size:0.92rem; margin-bottom:8px; color: var(--ink);
}
.field-input{
  display:flex; align-items:center; border: 1.5px solid var(--line); border-radius: var(--radius);
  overflow:hidden; background: var(--paper);
}
.field-input input[type="number"]{
  flex:1; border:none; background:transparent; padding: 14px 16px;
  font-family: var(--font-mono); font-size: 1.4rem; font-weight:600; color: var(--ink);
  min-width: 0;
}
.field-input input[type="number"]:focus{ outline: 2px solid var(--teal); outline-offset: -2px; }
.field-suffix{
  padding: 0 16px; font-family: var(--font-mono); color: var(--slate); font-weight:600;
}
input[type="range"]{
  width:100%; margin-top: 14px; accent-color: var(--teal); cursor:pointer;
}
.field-hint{ font-size: 0.82rem; color: var(--slate); margin-top: 8px; }

.unit-toggle{ display:flex; gap:8px; margin: 18px 0; }
.unit-btn{
  flex:1; padding: 9px 10px; border: 1.5px solid var(--line); background:#fff;
  border-radius: var(--radius); font-weight:600; font-size: 0.86rem; color: var(--slate);
}
.unit-btn.is-active{ background: var(--ink); border-color: var(--ink); color:#fff; }

.result-readout{
  margin-top: 22px; padding: 20px; background: var(--paper); border-radius: var(--radius);
  text-align:center; border: 1px solid var(--line);
}
.result-main{ display:flex; align-items:baseline; justify-content:center; gap:8px; }
.result-value{
  font-family: var(--font-mono); font-size: clamp(2.4rem, 6vw, 3.2rem); font-weight:700; color: var(--ink);
}
.result-unit{ font-family: var(--font-mono); font-size: 1.1rem; color: var(--slate); font-weight:600; }
.result-label{ display:block; margin-top: 6px; font-size: 0.85rem; color: var(--slate); letter-spacing:0.02em; }

.range-gauge{ margin-top: 26px; }
.gauge-svg{ width:100%; height:auto; display:block; }
#gaugePointer{ transition: transform .25s ease; }
#gaugePointerLabel{ transition: x .25s ease; }
.gauge-status{
  text-align:center; font-size: 0.9rem; font-weight:600; margin-top: 4px; color: var(--ink);
}

.calc-aside{ padding-top: 12px; }
.calc-aside h2{ font-size: 1.4rem; }

/* =========================== CHART =========================== */
.chart-section{ padding: 72px 0; background: var(--ink); color:#fff; }
.chart-section h2{ color:#fff; }
.chart-section .section-sub{ color: rgba(255,255,255,0.7); max-width: 60ch; }
.table-wrap{ overflow-x:auto; margin-top: 24px; border-radius: 8px; border: 1px solid rgba(255,255,255,0.14); }
.range-table{ width:100%; border-collapse: collapse; font-size: 0.95rem; min-width: 480px; }
.range-table th, .range-table td{ padding: 14px 18px; text-align:left; }
.range-table thead th{
  font-family: var(--font-mono); font-size: 0.76rem; text-transform: uppercase; letter-spacing: 0.05em;
  color: rgba(255,255,255,0.55); border-bottom: 1px solid rgba(255,255,255,0.14);
}
.range-table tbody td{ font-family: var(--font-mono); border-bottom: 1px solid rgba(255,255,255,0.08); }
.range-table tbody tr:last-child td{ border-bottom:none; }
.range-table td:first-child{ font-family: var(--font-body); font-weight:600; }
.row-normal td:first-child{ color: var(--zone-normal); }
.row-pre td:first-child{ color: var(--zone-pre); }
.row-high td:first-child{ color: var(--zone-high); }
.range-table.dense{ margin-top: 0; }
.range-table.dense td, .range-table.dense th{ padding: 10px 18px; }

/* =========================== HOW IT WORKS =========================== */
.how-section{ padding: 72px 0; }
.how-grid{ display:grid; grid-template-columns: repeat(3, 1fr); gap: 24px; margin-top: 28px; }
.how-card{
  background:#fff; border:1px solid var(--line); border-radius: 8px; padding: 24px;
}
.how-tag{
  display:inline-block; font-family: var(--font-mono); font-size: 0.74rem; text-transform:uppercase;
  letter-spacing: 0.05em; color: var(--teal); border: 1px solid var(--teal); border-radius: 20px;
  padding: 3px 10px; margin-bottom: 12px;
}
.how-card p{ margin:0; font-size: 0.94rem; }

/* =========================== FAQ =========================== */
.faq-section{ padding: 72px 0; background: var(--paper-alt); }
.faq-list{ margin-top: 24px; border-top: 1px solid var(--line); }
.faq-item{ border-bottom: 1px solid var(--line); }
.faq-q{
  width:100%; text-align:left; background:none; border:none; padding: 20px 4px;
  font-family: var(--font-display); font-size: 1.05rem; font-weight:600; color: var(--ink);
  display:flex; justify-content:space-between; align-items:center; gap: 16px;
}
.faq-icon{ position:relative; width:16px; height:16px; flex-shrink:0; }
.faq-icon::before, .faq-icon::after{
  content:""; position:absolute; background: var(--teal); top:50%; left:50%;
  transform: translate(-50%,-50%);
}
.faq-icon::before{ width:14px; height:2px; }
.faq-icon::after{ width:2px; height:14px; transition: transform .2s ease; }
.faq-q[aria-expanded="true"] .faq-icon::after{ transform: translate(-50%,-50%) rotate(90deg) scaleY(0); }
.faq-a{
  max-height:0; overflow:hidden; transition: max-height .25s ease;
}
.faq-a p{ padding: 0 4px 20px; margin:0; }

/* =========================== DISCLAIMER =========================== */
.disclaimer-section{ padding: 32px 0 56px; }
.disclaimer-section p{ font-size: 0.85rem; color: var(--slate); max-width: 80ch; }

/* =========================== FOOTER =========================== */
.site-footer{ background: var(--teal-dark); color: rgba(255,255,255,0.85); padding: 48px 0 28px; }
.footer-inner{
  display:flex; flex-wrap:wrap; justify-content:space-between; gap: 24px; padding-bottom: 20px;
  border-bottom: 1px solid rgba(255,255,255,0.15);
}
.footer-brand .brand-text{ font-family: var(--font-display); font-size:1.2rem; font-weight:700; color:#fff; }
.footer-brand .brand-text em{ font-style:normal; color: #6FD6C3; }
.footer-brand p{ color: rgba(255,255,255,0.6); font-size: 0.88rem; margin-top: 6px; }
.footer-nav{ display:flex; gap: 20px; flex-wrap:wrap; }
.footer-nav a{ color: rgba(255,255,255,0.8); text-decoration:none; font-size: 0.9rem; }
.footer-nav a:hover{ color:#fff; }
.footer-copy{ font-size: 0.78rem; color: rgba(255,255,255,0.5); margin-top: 18px; margin-bottom:0; }

/* =========================== ARTICLE / CONTENT PAGES =========================== */
.page-hero{ padding: 48px 0 8px; }
.page-hero .eyebrow{ margin-bottom: 10px; }
.page-hero h1{ font-size: clamp(1.9rem, 4.5vw, 2.8rem); max-width: 20ch; }
.page-hero p{ max-width: 62ch; font-size: 1.05rem; }
.breadcrumb{
  font-family: var(--font-mono); font-size: 0.8rem; color: var(--slate); margin-bottom: 14px;
}
.breadcrumb a{ color: var(--slate); text-decoration:none; }
.breadcrumb a:hover{ color: var(--teal); }

.article-section{ padding: 24px 0 64px; }
.article-layout{
  display:grid; grid-template-columns: minmax(0,1fr) 240px; gap: 56px; align-items:start;
}
.article-toc{
  position: sticky; top: 90px; border-left: 2px solid var(--line); padding-left: 18px;
}
.article-toc p{
  font-family: var(--font-mono); font-size: 0.74rem; text-transform:uppercase; letter-spacing:0.06em;
  color: var(--slate); margin-bottom: 10px;
}
.article-toc ul{ list-style:none; margin:0; padding:0; display:flex; flex-direction:column; gap:9px; }
.article-toc a{
  color: var(--ink-soft); text-decoration:none; font-size: 0.88rem; line-height:1.3; display:block;
}
.article-toc a:hover{ color: var(--teal); }

.article-body h2{ margin-top: 2.2em; scroll-margin-top: 90px; }
.article-body h2:first-child{ margin-top: 0; }
.article-body h3{ font-size: 1.15rem; margin-top: 1.6em; scroll-margin-top: 90px; }
.article-body p{ max-width: 74ch; }
.article-body ul, .article-body ol{ max-width: 74ch; color: var(--ink-soft); padding-left: 1.3em; }
.article-body li{ margin-bottom: 0.5em; }
.article-body strong{ color: var(--ink); }

.callout{
  border-left: 3px solid var(--teal); background: var(--paper-alt); border-radius: 0 8px 8px 0;
  padding: 16px 20px; margin: 1.6em 0; max-width: 74ch;
}
.callout p{ margin:0; font-size: 0.94rem; }
.callout.warn{ border-left-color: var(--coral); }

.formula-box{
  font-family: var(--font-mono); background: var(--ink); color: #fff; border-radius: 8px;
  padding: 20px 24px; margin: 1.4em 0; max-width: 74ch; font-size: 1.02rem; overflow-x:auto;
}
.formula-box .fx-label{ display:block; font-size: 0.72rem; letter-spacing:0.06em; text-transform:uppercase; color: #6FD6C3; margin-bottom: 6px; }

.mini-cards{ display:grid; grid-template-columns: repeat(3,1fr); gap:16px; margin: 1.6em 0; max-width: 74ch; }
.mini-card{ border: 1px solid var(--line); border-radius: 8px; padding: 16px; background:#fff; }
.mini-card .num{ font-family: var(--font-mono); font-weight:700; color: var(--teal); font-size:1.1rem; }
.mini-card p{ margin: 6px 0 0; font-size: 0.86rem; }

.cross-links{
  display:flex; gap:16px; flex-wrap:wrap; margin: 2em 0; max-width: 74ch;
}
.cross-link-card{
  flex:1; min-width: 220px; border:1px solid var(--line); border-radius:8px; padding:18px; text-decoration:none;
  background: #fff; transition: border-color .15s ease, transform .15s ease;
}
.cross-link-card:hover{ border-color: var(--teal); transform: translateY(-2px); }
.cross-link-card .clc-tag{ font-family: var(--font-mono); font-size:0.72rem; text-transform:uppercase; color: var(--teal); letter-spacing:0.05em; }
.cross-link-card h3{ margin: 8px 0 4px; font-size: 1.05rem; color: var(--ink); }
.cross-link-card p{ margin:0; font-size: 0.86rem; color: var(--slate); }

.full-chart-wrap{ margin-top: 12px; }
.chart-filter{ display:flex; gap:8px; margin: 18px 0; flex-wrap:wrap; }
.chart-filter button{
  padding: 8px 14px; border-radius: 20px; border: 1.5px solid var(--line); background:#fff;
  font-size: 0.82rem; font-weight:600; color: var(--slate);
}
.chart-filter button.is-active{ background: var(--ink); border-color: var(--ink); color:#fff; }

@media (max-width: 900px){
  .article-layout{ grid-template-columns: 1fr; }
  .article-toc{ position: static; border-left:none; border-top: 1px solid var(--line); padding: 18px 0 0; }
  .article-toc ul{ flex-direction:row; flex-wrap:wrap; gap: 8px 16px; }
  .mini-cards{ grid-template-columns: 1fr; }
}

/* =========================== RESPONSIVE =========================== */
@media (max-width: 860px){
  .main-nav{
    position:absolute; top: 100%; left:0; right:0; background: var(--paper);
    flex-direction:column; gap:0; border-bottom: 1px solid var(--line);
    max-height:0; overflow:hidden; transition: max-height .25s ease;
  }
  .main-nav.is-open{ max-height: 400px; }
  .main-nav a{ padding: 16px 24px; border-bottom: 1px solid var(--line); width:100%; }
  .nav-toggle{ display:flex; }

  .calc-section .section-inner, .reverse-layout{
    grid-template-columns: 1fr; gap: 32px;
  }
  .reverse-layout .slip-card, .reverse-layout .calc-aside{ order:0; }
  .how-grid{ grid-template-columns: 1fr; }
  .footer-inner{ flex-direction:column; }
}

@media (max-width: 480px){
  .hero{ padding: 44px 0 28px; }
  .slip-head, .slip-body, .slip-foot{ padding-left: 18px; padding-right: 18px; }
  .btn{ width:100%; }
  .hero-actions{ flex-direction: column; }
}