/* ---------- Tokens (matches aclassvlsi.com root site) ---------- */
:root{
  --bg: #FFFFFF;
  --bg-raised: #F7F8FA;
  --bg-sunken: #EEF0F3;
  --ink: #12181F;
  --ink-dim: #4A5568;
  --ink-faint: #8A94A6;
  --line: rgba(18,24,31,0.1);
  --line-strong: rgba(18,24,31,0.22);
  --design: #1F7E8C;
  --design-ink: #0F4A54;
  --design-tint: rgba(31,126,140,0.12);
  --verify: #B8600F;
  --verify-ink: #7A3F09;
  --verify-tint: rgba(184,96,15,0.13);
  --c1: #2E8B4E; --c1-tint: rgba(46,139,78,0.12);
  --c2: #2563C4; --c2-tint: rgba(37,99,196,0.12);
  --c3: #C43B36; --c3-tint: rgba(196,59,54,0.12);
  --shadow: 0 1px 2px rgba(18,24,31,0.06), 0 8px 24px -12px rgba(18,24,31,0.18);
  --radius-sm: 3px;
  --radius: 6px;

  --font-display: "Bahnschrift", "SF Compact Display", "Segoe UI Semibold", "Segoe UI", system-ui, sans-serif;
  --font-body: "Segoe UI", -apple-system, "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
  --font-mono: "Cascadia Code", "SF Mono", Menlo, Consolas, "Roboto Mono", monospace;
}

*{ box-sizing: border-box; }
html{ scroll-behavior: smooth; }
body{
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a{ color: inherit; }
h1,h2,h3,h4{
  font-family: var(--font-display);
  text-wrap: balance;
  margin: 0;
  letter-spacing: 0.2px;
}
p{ margin: 0; }
::selection{ background: var(--design); color: #fff; }
:focus-visible{ outline: 2px solid var(--design); outline-offset: 3px; }
.container{
  max-width: 1160px;
  margin-inline: auto;
  padding-inline: clamp(1.25rem, 4vw, 3rem);
}
.eyebrow{
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
  display: flex;
  align-items: center;
  gap: 0.6em;
}
.eyebrow::before{
  content: "";
  width: 1.4em; height: 1px;
  background: var(--ink-faint);
  display: inline-block;
}

/* ---------- Nav (blog pages link back to the main site) ---------- */
.nav{
  position: sticky; top: 0; z-index: 50;
  background: #FFFFFF;
  border-bottom: 1px solid rgba(11,27,51,0.1);
}
.nav-row{
  display: grid;
  grid-template-columns: minmax(0,1fr) auto minmax(0,1fr);
  align-items: center;
  gap: 1rem;
  padding-block: 0.9rem;
}
.brand{
  grid-column: 2;
  justify-self: center;
  display: flex; align-items: center; gap: 0.9rem; text-decoration: none;
}
.brand-mark{ width: clamp(40px, 6vw, 52px); height: clamp(40px, 6vw, 52px); flex: none; border-radius: 9px; object-fit: cover; display: block; }
.brand-text{ display: flex; flex-direction: column; gap: 0.15rem; }
.brand-name{
  font-family: var(--font-display);
  font-size: clamp(1.3rem, 4.5vw, 1.9rem);
  font-weight: 800;
  letter-spacing: 0.01em;
  line-height: 1;
  white-space: nowrap;
  color: #0B1B33;
}
.brand-tagline{
  font-family: var(--font-body);
  font-size: clamp(0.68rem, 1.4vw, 0.8rem);
  font-weight: 500;
  letter-spacing: 0.02em;
  color: #5B6878;
}
.nav-links{
  grid-column: 1;
  justify-self: start;
  display: flex; align-items: center; gap: 1.4rem;
}
.nav-links a{
  font-size: 0.9rem; font-weight: 600;
  text-decoration: none;
  color: var(--ink-dim);
}
.nav-links a:hover{ color: var(--ink); }
.nav-links a.is-current{ color: var(--design-ink); }
.nav-cta{
  grid-column: 3;
  justify-self: end;
}
.nav-cta a{
  display: inline-flex; align-items: center; gap: 0.5em;
  font-size: 0.85rem; font-weight: 700;
  color: #fff;
  text-decoration: none;
  padding: 0.5rem 1rem;
  border-radius: 999px;
  background: var(--design);
  white-space: nowrap;
}
.nav-cta a:hover{ opacity: 0.9; }
@media (max-width: 700px){
  .nav-row{ grid-template-columns: 1fr; row-gap: 0.6rem; }
  .brand{ grid-column: 1; justify-self: center; }
  .nav-links{ grid-column: 1; justify-self: center; }
  .nav-cta{ grid-column: 1; justify-self: center; }
}

/* ---------- Series header / index page ---------- */
.series-hero{ padding-block: clamp(2.5rem, 6vw, 4.5rem) clamp(1.5rem, 4vw, 2.5rem); border-bottom: 1px solid var(--line); }
.series-hero h1{
  font-size: clamp(1.9rem, 4vw, 2.7rem);
  font-weight: 600;
  line-height: 1.12;
  margin-top: 0.7rem;
}
.series-hero p{
  color: var(--ink-dim);
  font-size: 1.05rem;
  max-width: 62ch;
  margin-top: 1rem;
}
.series-body{ padding-block: clamp(2.5rem, 6vw, 4rem); }
.series-phase{ margin-bottom: clamp(2.2rem, 4vw, 3rem); }
.series-phase h2{
  font-size: 1.05rem;
  font-weight: 700;
  font-family: var(--font-mono);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin-bottom: 1.1rem;
}
.series-grid{
  display: grid;
  grid-template-columns: repeat(2, minmax(0,1fr));
  gap: 1.1rem;
}
.series-card{
  display: flex; flex-direction: column; gap: 0.6rem;
  background: var(--bg-raised);
  border: 1px solid var(--line);
  border-left: 3px solid var(--line-strong);
  border-radius: var(--radius);
  padding: 1.4rem 1.5rem;
  text-decoration: none;
  transition: border-color 0.15s ease, transform 0.12s ease;
}
.series-card:hover{ border-left-color: var(--design); transform: translateX(2px); }
.series-card .part-no{
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  color: var(--ink-faint);
}
.series-card h3{ font-size: 1.08rem; font-weight: 600; color: var(--ink); }
.series-card p{ font-size: 0.92rem; color: var(--ink-dim); }
@media (max-width: 700px){ .series-grid{ grid-template-columns: 1fr; } }

/* ---------- Article page ---------- */
.post-header{ padding-block: clamp(2.2rem, 5vw, 3.5rem) clamp(1.6rem, 4vw, 2.2rem); border-bottom: 1px solid var(--line); }
.post-header .container{ max-width: 760px; }
.post-meta{
  display: flex; flex-wrap: wrap; align-items: center; gap: 0.7rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-faint);
  margin-top: 0.9rem;
}
.post-meta .dot{ width: 4px; height: 4px; border-radius: 50%; background: var(--ink-faint); display: inline-block; }
.post-header h1{
  font-size: clamp(1.7rem, 3.6vw, 2.4rem);
  font-weight: 600;
  line-height: 1.16;
  margin-top: 0.8rem;
}
.post-header .dek{
  font-size: 1.05rem;
  color: var(--ink-dim);
  margin-top: 0.9rem;
  max-width: 62ch;
}

.post-body{ padding-block: clamp(2rem, 5vw, 3rem); }
.prose{
  max-width: 700px;
  margin-inline: auto;
  display: flex;
  flex-direction: column;
  gap: 1.3rem;
}
.prose h2{
  font-size: clamp(1.3rem, 2.4vw, 1.55rem);
  font-weight: 600;
  margin-top: 0.8rem;
}
.prose h3{
  font-size: 1.12rem;
  font-weight: 700;
  margin-top: 0.3rem;
}
.prose p{ color: var(--ink-dim); font-size: 1rem; line-height: 1.7; }
.prose strong{ color: var(--ink); }
.prose ul, .prose ol{ color: var(--ink-dim); font-size: 1rem; line-height: 1.65; padding-left: 1.3rem; display: flex; flex-direction: column; gap: 0.5rem; }
.prose li::marker{ color: var(--ink-faint); }
.prose code{
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--bg-sunken);
  padding: 0.15em 0.4em;
  border-radius: 3px;
  color: var(--design-ink);
}
.prose a{ color: var(--design-ink); text-decoration: underline; text-decoration-color: var(--line-strong); }
.prose a:hover{ text-decoration-color: var(--design-ink); }

.callout{
  border-left: 3px solid var(--design);
  background: var(--design-tint);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 1rem 1.3rem;
  display: flex; flex-direction: column; gap: 0.5rem;
}
.callout.callout--warn{ border-left-color: var(--verify); background: var(--verify-tint); }
.callout p{ color: var(--ink); font-size: 0.96rem; margin: 0; }
.callout .callout-label{
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--design-ink);
  font-weight: 700;
}
.callout.callout--warn .callout-label{ color: var(--verify-ink); }

.code-block{
  background: #0F1620;
  color: #D9E2EC;
  border-radius: var(--radius);
  padding: 1.1rem 1.3rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.86rem;
  line-height: 1.6;
  box-shadow: var(--shadow);
}
.code-block .code-label{
  display: block;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #7C8CA0;
  margin-bottom: 0.7rem;
}
.code-block code{ background: none; padding: 0; color: inherit; white-space: pre; }

.prose table{ width: 100%; border-collapse: collapse; font-size: 0.94rem; }
.prose th, .prose td{ text-align: left; padding: 0.55rem 0.8rem; border-bottom: 1px solid var(--line); color: var(--ink-dim); }
.prose th{ color: var(--ink); font-weight: 700; font-family: var(--font-display); }

.figure{ display: flex; flex-direction: column; gap: 0.6rem; }
.figure svg{ width: 100%; height: auto; display: block; }
.figure-wrap{
  background: var(--bg-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.1rem;
}
.figure figcaption{
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-faint);
  text-align: center;
}

.post-footer{ border-top: 1px solid var(--line); padding-block: clamp(2rem, 4vw, 2.6rem); }
.post-footer .container{ max-width: 760px; }
.post-nav{
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}
.post-nav a{
  display: flex; flex-direction: column; gap: 0.4rem;
  padding: 1.1rem 1.3rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  text-decoration: none;
  background: var(--bg-raised);
}
.post-nav a:hover{ border-color: var(--line-strong); }
.post-nav .nav-dir{ font-family: var(--font-mono); font-size: 0.7rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-faint); }
.post-nav .nav-title{ font-size: 0.96rem; font-weight: 600; color: var(--ink); }
.post-nav a.next{ grid-column: 2; text-align: right; align-items: flex-end; }
.post-nav a.prev{ grid-column: 1; }
.post-nav .full-width{ grid-column: 1 / -1; text-align: center; align-items: center; }
@media (max-width: 600px){
  .post-nav{ grid-template-columns: 1fr; }
  .post-nav a.next{ grid-column: 1; text-align: left; align-items: flex-start; }
}

.back-to-series{
  display: inline-flex; align-items: center; gap: 0.5em;
  font-size: 0.88rem; font-weight: 600;
  color: var(--ink-dim);
  text-decoration: none;
  margin-bottom: 1.4rem;
}
.back-to-series:hover{ color: var(--ink); }

/* ---------- Footer (matches root site) ---------- */
.site-footer{ border-top: 1px solid var(--line); }
.footer-row{
  padding-block: 2rem;
  display: flex; flex-wrap: wrap; gap: 1rem;
  align-items: center; justify-content: space-between;
  font-size: 0.85rem; color: var(--ink-faint);
}
.footer-links{ display: flex; gap: 1.4rem; list-style: none; padding: 0; margin: 0; }
.footer-links a{ text-decoration: none; color: var(--ink-faint); }
.footer-links a:hover{ color: var(--ink-dim); }

.whatsapp-float{
  position: fixed; bottom: 1.4rem; right: 1.4rem; z-index: 100;
  width: 56px; height: 56px;
  border-radius: 50%;
  background: #22B366;
  display: flex; align-items: center; justify-content: center;
  color: #fff;
  box-shadow: 0 4px 14px rgba(0,0,0,0.28);
  text-decoration: none;
  transition: transform 0.15s ease;
}
.whatsapp-float:hover{ transform: scale(1.07); }
@media (max-width: 640px){
  .whatsapp-float{ width: 50px; height: 50px; bottom: 1rem; right: 1rem; }
}