:root {
  --navy-950: #071825;
  --navy-900: #102a3d;
  --ink: #13293a;
  --ivory: #f6f1e7;
  --soft: #fbf8f1;
  --gold: #c6a15b;
  --gold-dark: #755b29;
  --blue: #235a8c;
  --muted: #667989;
  --line: rgba(19, 41, 58, 0.16);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; background: var(--navy-950); }
body {
  margin: 0;
  color: var(--ink);
  background: var(--ivory);
  font-family: "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; }
a { color: inherit; }
a:focus-visible, button:focus-visible, summary:focus-visible { outline: 2px solid #2c6eab; outline-offset: 4px; }

.article-nav {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 76px;
  padding: 0 5vw;
  color: #fff;
  background: rgba(7, 24, 37, 0.96);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(14px);
}
.article-nav img { display: block; width: auto; height: 46px; }
.article-nav-links { display: flex; align-items: center; gap: 1.6rem; }
.article-nav a { text-decoration: none; }
.article-nav-link { color: #9fb1c0; font-size: 0.72rem; letter-spacing: 0.11em; text-transform: uppercase; }
.article-nav-link:hover { color: var(--gold); }
.article-nav-cta { padding: 0.8rem 1.1rem; color: var(--gold); border: 1px solid var(--gold); font-size: 0.7rem; letter-spacing: 0.1em; text-transform: uppercase; }
.article-nav-cta:hover { color: var(--navy-950); background: var(--gold); }

.article-hero {
  position: relative;
  overflow: hidden;
  color: #fff;
  background: var(--navy-950);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}
.article-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  opacity: 0.18;
  background-image: linear-gradient(rgba(86, 142, 184, 0.22) 1px, transparent 1px), linear-gradient(90deg, rgba(86, 142, 184, 0.22) 1px, transparent 1px);
  background-size: 64px 64px;
}
.article-hero-inner {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1.04fr) minmax(340px, 0.96fr);
  gap: clamp(3rem, 6vw, 7rem);
  align-items: center;
  width: min(1440px, 90vw);
  margin: 0 auto;
  padding: clamp(4.5rem, 8vw, 8rem) 0;
}
.article-kicker { margin-bottom: 1.2rem; color: var(--gold); font-size: 0.72rem; letter-spacing: 0.15em; text-transform: uppercase; }
.article-title { max-width: 900px; margin: 0 0 1.4rem; font-family: "Libre Baskerville", Georgia, serif; font-size: clamp(2.7rem, 5.5vw, 5.6rem); font-weight: 400; line-height: 0.98; letter-spacing: -0.04em; }
.article-deck { max-width: 730px; margin: 0; color: #b5c3ce; font-size: clamp(1.04rem, 1.4vw, 1.25rem); font-weight: 400; line-height: 1.75; }
.article-meta { display: flex; flex-wrap: wrap; gap: 0.8rem 1.5rem; margin-top: 2rem; color: #8097a8; font-size: 0.68rem; letter-spacing: 0.1em; text-transform: uppercase; }
.article-cover { overflow: hidden; border: 1px solid rgba(198, 161, 91, 0.45); box-shadow: 0 38px 80px -38px rgba(0, 0, 0, 0.75); aspect-ratio: 2 / 3; background: #e9e1d1; }
.article-cover img { display: block; width: 100%; height: 100%; object-fit: cover; }

.article-main {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(250px, 320px);
  gap: clamp(3rem, 6vw, 7rem);
  width: min(1180px, 90vw);
  margin: 0 auto;
  padding: clamp(4rem, 8vw, 7rem) 0;
}
.article-prose { min-width: 0; max-width: 780px; }
.article-prose h2 { margin: 3rem 0 1rem; color: var(--ink); font-family: "Libre Baskerville", Georgia, serif; font-size: clamp(1.7rem, 3vw, 2.35rem); font-weight: 400; line-height: 1.18; letter-spacing: -0.025em; }
.article-prose h2:first-child { margin-top: 0; }
.article-prose h3 { margin: 2rem 0 0.7rem; color: var(--blue); font-size: 0.78rem; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; }
.article-prose p, .article-prose li { color: rgba(19, 41, 58, 0.79); font-size: 1rem; line-height: 1.82; }
.article-prose p { margin: 0 0 1rem; }
.article-prose ul, .article-prose ol { margin: 0 0 1.4rem; padding-left: 1.3rem; }
.article-prose li { margin-bottom: 0.65rem; padding-left: 0.25rem; }
.article-prose strong { color: var(--ink); font-weight: 600; }
.article-formula { margin: 2rem 0; padding: 1.6rem 1.8rem; color: #fff; background: var(--navy-900); border-left: 4px solid var(--gold); }
.article-formula-label { margin-bottom: 0.55rem; color: #e8cb8f; font-size: 0.65rem; letter-spacing: 0.13em; text-transform: uppercase; }
.article-formula-value { font-family: "Libre Baskerville", Georgia, serif; font-size: clamp(1.25rem, 2.2vw, 1.7rem); line-height: 1.4; }
.article-example { margin: 2.2rem 0; padding: 1.7rem; background: #efe7d6; border: 1px solid var(--line); }
.article-example h3 { margin-top: 0; color: var(--gold-dark); }
.article-takeaway { margin: 3rem 0; padding: 2rem; color: #fff; background: var(--navy-950); border: 1px solid rgba(198, 161, 91, 0.55); }
.article-takeaway h2 { margin-top: 0; color: #fff; font-size: 1.7rem; }
.article-takeaway li { color: #c5d0d8; }
.article-questions { margin-top: 3rem; border-top: 1px solid var(--line); }
.article-questions details { padding: 1rem 0; border-bottom: 1px solid var(--line); }
.article-questions summary { position: relative; padding-right: 2rem; color: var(--ink); cursor: pointer; font-weight: 600; list-style: none; }
.article-questions summary::-webkit-details-marker { display: none; }
.article-questions summary::after { content: "+"; position: absolute; right: 0; color: var(--gold-dark); font-size: 1.2rem; }
.article-questions details[open] summary::after { content: "−"; }
.article-questions p { margin: 0.8rem 0 0; font-size: 0.95rem; }
.article-disclaimer { margin-top: 3rem !important; padding-top: 1.3rem; color: rgba(19, 41, 58, 0.63) !important; border-top: 1px solid var(--line); font-size: 0.76rem !important; line-height: 1.7 !important; }

.article-aside { min-width: 0; }
.aside-sticky { position: sticky; top: 108px; }
.aside-panel { margin-bottom: 1rem; padding: 1.5rem; border: 1px solid var(--line); background: rgba(255, 255, 255, 0.28); }
.aside-panel-dark { color: #fff; background: var(--navy-900); border-color: rgba(198, 161, 91, 0.45); }
.aside-label { margin-bottom: 0.8rem; color: var(--gold-dark); font-size: 0.64rem; letter-spacing: 0.12em; text-transform: uppercase; }
.aside-panel-dark .aside-label { color: #e8cb8f; }
.aside-panel h2 { margin: 0 0 0.75rem; font-family: "Libre Baskerville", Georgia, serif; font-size: 1.35rem; font-weight: 400; line-height: 1.3; }
.aside-panel p, .aside-panel li { margin: 0; color: rgba(19, 41, 58, 0.72); font-size: 0.83rem; line-height: 1.65; }
.aside-panel-dark p, .aside-panel-dark li { color: #bdcbd4; }
.aside-panel ul { margin: 0; padding-left: 1.1rem; }
.aside-panel li { margin-bottom: 0.55rem; }
.source-list { display: grid; gap: 0.75rem; }
.source-list a { color: var(--blue); font-size: 0.8rem; line-height: 1.5; text-decoration-thickness: 1px; text-underline-offset: 3px; }

.article-next { color: #fff; background: var(--navy-900); border-top: 1px solid rgba(255, 255, 255, 0.08); }
.article-next-inner { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); width: min(1180px, 90vw); margin: 0 auto; }
.article-next a { display: block; padding: 2.2rem 0; text-decoration: none; }
.article-next a + a { padding-left: 2rem; text-align: right; border-left: 1px solid rgba(255, 255, 255, 0.1); }
.next-label { display: block; margin-bottom: 0.45rem; color: var(--gold); font-size: 0.63rem; letter-spacing: 0.12em; text-transform: uppercase; }
.next-title { color: #d9e1e6; font-family: "Libre Baskerville", Georgia, serif; font-size: 1.05rem; line-height: 1.4; }

.article-footer { padding: 3rem 5vw; color: #9fb1c0; background: var(--navy-950); border-top: 1px solid rgba(255, 255, 255, 0.08); }
.article-footer-inner { display: grid; grid-template-columns: 1.3fr 1fr 1fr; gap: 3rem; width: min(1180px, 100%); margin: 0 auto; }
.article-footer img { width: auto; height: 38px; margin-bottom: 1rem; }
.article-footer p { max-width: 500px; margin: 0; font-size: 0.78rem; line-height: 1.7; }
.article-footer h2 { margin: 0 0 0.8rem; color: var(--gold); font-size: 0.65rem; font-weight: 500; letter-spacing: 0.13em; text-transform: uppercase; }
.article-footer-links { display: grid; gap: 0.55rem; }
.article-footer a { color: #9fb1c0; font-size: 0.82rem; text-decoration: none; }
.article-footer a:hover { color: #fff; }

@media (max-width: 900px) {
  .article-hero-inner { grid-template-columns: 1fr; padding-top: 3.5rem; }
  .article-cover { width: min(520px, 100%); }
  .article-main { grid-template-columns: 1fr; }
  .aside-sticky { position: static; }
  .article-aside { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; }
  .article-footer-inner { grid-template-columns: 1fr 1fr; }
  .article-footer-brand { grid-column: 1 / -1; }
}

@media (max-width: 640px) {
  .article-nav { min-height: 68px; padding: 0 1.2rem; }
  .article-nav img { height: 40px; }
  .article-nav-links { gap: 0.8rem; }
  .article-nav-link { display: none; }
  .article-nav-cta { padding: 0.65rem 0.75rem; font-size: 0.61rem; }
  .article-hero-inner, .article-main { width: min(100% - 2.4rem, 1180px); }
  .article-title { font-size: clamp(2.35rem, 12vw, 3.65rem); }
  .article-main { padding-top: 3.5rem; }
  .article-prose p, .article-prose li { font-size: 0.96rem; }
  .article-aside { grid-template-columns: 1fr; }
  .article-next-inner { grid-template-columns: 1fr; }
  .article-next a + a { padding-left: 0; text-align: left; border-top: 1px solid rgba(255, 255, 255, 0.1); border-left: 0; }
  .article-footer-inner { grid-template-columns: 1fr; gap: 2rem; }
  .article-footer-brand { grid-column: auto; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

/* Tables inside lessons (worked examples) */
.article-prose table { width: 100%; border-collapse: collapse; margin: 0 0 1.6rem; font-size: 0.95rem; }
.article-prose thead th { text-align: left; font-size: 0.7rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--gold-dark); padding: 0.6rem 0.75rem; border-bottom: 2px solid var(--line); }
.article-prose tbody td { padding: 0.6rem 0.75rem; border-bottom: 1px solid var(--line); color: rgba(19, 41, 58, 0.82); vertical-align: top; }
.article-prose tbody tr:nth-child(even) td { background: rgba(19, 41, 58, 0.03); }
.article-prose ol { list-style: decimal; }