:root {
  --ink: #080908;
  --ink-soft: #151916;
  --paper: #f3efe7;
  --paper-dim: #d6d0c5;
  --muted: #9b9d96;
  --line: rgba(243, 239, 231, 0.16);
  --line-dark: rgba(8, 9, 8, 0.16);
  --gold: #d3b778;
  --gold-dark: #987d48;
  --orange: #eea562;
  --max: 1160px;
}

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

html {
  scroll-behavior: smooth;
  background: var(--ink);
}

body {
  min-width: 320px;
  margin: 0;
  background:
    radial-gradient(circle at 80% 10%, rgba(211, 183, 120, 0.08), transparent 30rem),
    var(--ink);
  color: var(--paper);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 1rem;
  line-height: 1.65;
}

a {
  color: inherit;
}

.skip-link {
  position: fixed;
  top: -4rem;
  left: 1rem;
  z-index: 10;
  padding: 0.7rem 1rem;
  border-radius: 999px;
  background: var(--paper);
  color: var(--ink);
}

.skip-link:focus {
  top: 1rem;
}

.container {
  width: min(calc(100% - 3rem), var(--max));
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 5;
  border-bottom: 1px solid var(--line);
  background: rgba(8, 9, 8, 0.88);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.course-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  min-height: 4.75rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  color: var(--paper);
  text-decoration: none;
  white-space: nowrap;
}

.brand-mark {
  position: relative;
  width: 1.55rem;
  height: 1.85rem;
  border: 1px solid var(--paper);
  border-radius: 0.15rem;
  overflow: hidden;
}

.brand-mark::after {
  position: absolute;
  content: "";
  inset: 0.25rem;
  background: var(--paper);
  clip-path: polygon(0 0, 61% 0, 61% 100%, 0 100%);
}

.brand-name {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.06rem;
  letter-spacing: -0.04em;
}

.course-nav-links {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  color: var(--paper-dim);
  font-size: 0.86rem;
}

.course-nav-links a:not(.button) {
  text-decoration: none;
}

.course-nav-links a:not(.button):hover,
.course-nav-links a:not(.button):focus-visible {
  color: var(--paper);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.55rem;
  min-height: 2.85rem;
  padding: 0.7rem 1.1rem;
  border: 1px solid transparent;
  border-radius: 999px;
  background: var(--paper);
  color: var(--ink);
  font-size: 0.88rem;
  font-weight: 700;
  line-height: 1.2;
  text-decoration: none;
  transition: transform 180ms ease, background 180ms ease;
}

.button:hover,
.button:focus-visible {
  transform: translateY(-2px);
  background: #fff;
}

.button-dark {
  background: var(--ink);
  color: var(--paper);
}

.button-dark:hover,
.button-dark:focus-visible {
  background: #252824;
}

.course-shell {
  padding-block: clamp(3rem, 7vw, 6rem) clamp(5rem, 10vw, 9rem);
}

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  color: var(--muted);
  font-size: 0.78rem;
}

.breadcrumbs a {
  color: var(--paper-dim);
  text-decoration: none;
}

.breadcrumbs a:hover,
.breadcrumbs a:focus-visible {
  color: var(--paper);
  text-decoration: underline;
  text-underline-offset: 0.2em;
}

.course-hero {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(16rem, 0.9fr);
  gap: clamp(2.5rem, 8vw, 8rem);
  align-items: end;
  padding-block: clamp(4rem, 8vw, 7rem) 4rem;
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  color: var(--gold);
  font-size: 0.76rem;
  font-weight: 700;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-block: 0;
}

h1,
h2,
h3 {
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 400;
  letter-spacing: -0.06em;
  line-height: 0.98;
}

h1 {
  max-width: 11ch;
  margin-top: 1.25rem;
  font-size: clamp(3.1rem, 7vw, 7rem);
}

h2 {
  font-size: clamp(2rem, 4vw, 4rem);
}

h3 {
  font-size: clamp(1.45rem, 2.4vw, 2.2rem);
}

.course-deck {
  max-width: 38rem;
  margin-top: 1.6rem;
  color: var(--paper-dim);
  font-size: clamp(1.05rem, 1.8vw, 1.24rem);
}

.course-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-top: 1.5rem;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.course-stat {
  display: grid;
  gap: 0.1rem;
  padding: 0.85rem 0.8rem 0.85rem 0;
}

.course-stat + .course-stat {
  padding-left: 0.8rem;
  border-left: 1px solid var(--line);
}

.course-stat strong {
  color: var(--paper);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.25rem;
  font-weight: 400;
}

.course-stat span {
  color: var(--muted);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.course-side-note {
  padding-top: 1rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.92rem;
}

.course-side-note strong {
  color: var(--paper);
  font-weight: 600;
}

.course-section {
  padding-block: clamp(3.5rem, 7vw, 6rem);
  border-bottom: 1px solid var(--line);
}

.course-section > h2 {
  max-width: 12ch;
}

.course-section > p {
  max-width: 42rem;
  margin-top: 1rem;
  color: var(--paper-dim);
}

.lesson-index {
  display: grid;
  gap: 1px;
  margin: 2.8rem 0 0;
  padding: 0;
  border: 1px solid var(--line);
  background: var(--line);
  list-style: none;
}

.lesson-index li {
  display: grid;
  grid-template-columns: 4rem 1fr auto;
  gap: 1.2rem;
  align-items: start;
  padding: 1.35rem;
  background: #171d1a;
}

.lesson-index li:nth-child(even) {
  background: #1b211d;
}

.lesson-index-number {
  color: var(--gold);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.12em;
}

.lesson-index h3 {
  font-size: clamp(1.5rem, 2.5vw, 2.35rem);
}

.lesson-index h3 a {
  text-decoration: none;
}

.lesson-index h3 a:hover,
.lesson-index h3 a:focus-visible {
  color: var(--gold);
}

.lesson-index p {
  max-width: 42rem;
  margin-top: 0.5rem;
  color: var(--muted);
  font-size: 0.94rem;
}

.lesson-index-link {
  align-self: center;
  color: var(--gold);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-decoration: none;
  text-transform: uppercase;
  white-space: nowrap;
}

.lesson-index-link:hover,
.lesson-index-link:focus-visible {
  color: var(--paper);
}

.course-cta {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 2rem;
  align-items: end;
  margin-top: 3.5rem;
  padding: 1.5rem;
  background: var(--gold);
  color: var(--ink);
}

.course-cta p {
  max-width: 38rem;
  margin-top: 0.75rem;
  color: #4e4227;
}

.lesson-hero {
  padding-block: clamp(3.5rem, 8vw, 7rem) 3rem;
  border-bottom: 1px solid var(--line);
}

.lesson-hero h1 {
  max-width: 12ch;
}

.lesson-number-large {
  color: var(--gold);
  font-family: Inter, ui-sans-serif, system-ui, sans-serif;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.14em;
}

.lesson-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 16rem;
  gap: clamp(2.5rem, 8vw, 8rem);
  align-items: start;
  padding-top: 3.8rem;
}

.lesson-content {
  max-width: 47rem;
}

.lesson-content .lead {
  color: var(--paper-dim);
  font-size: 1.16rem;
}

.lesson-content h2 {
  margin-top: 3.3rem;
}

.lesson-content h3 {
  margin-top: 2rem;
}

.lesson-content p,
.lesson-content ul,
.lesson-content ol {
  margin-top: 1rem;
}

.lesson-content li + li {
  margin-top: 0.55rem;
}

.lesson-content strong {
  color: var(--paper);
  font-weight: 650;
}

.lesson-table-wrap {
  margin-top: 1.6rem;
  overflow-x: auto;
  border: 1px solid var(--line);
}

.lesson-table {
  width: 100%;
  min-width: 38rem;
  border-collapse: collapse;
  font-size: 0.92rem;
}

.lesson-table th,
.lesson-table td {
  padding: 0.85rem 0.9rem;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

.lesson-table tr:last-child th,
.lesson-table tr:last-child td {
  border-bottom: 0;
}

.lesson-table th {
  width: 28%;
  color: var(--gold);
  font-weight: 600;
}

.lesson-table td {
  color: var(--paper-dim);
}

.callout,
.exercise {
  margin-top: 1.8rem;
  padding: 1.25rem 1.35rem;
  border-left: 2px solid var(--gold);
  background: #151916;
}

.callout strong,
.exercise strong {
  color: var(--gold);
}

.exercise {
  background: rgba(211, 183, 120, 0.1);
}

.exercise h3 {
  margin-top: 0;
  color: var(--paper);
  font-size: 1.55rem;
}

.exercise p {
  color: var(--paper-dim);
}

.exercise-lines {
  display: grid;
  gap: 0.8rem;
  margin-top: 1.1rem;
}

.exercise-line {
  min-height: 1.7rem;
  border-bottom: 1px solid rgba(243, 239, 231, 0.32);
}

.lesson-aside {
  position: sticky;
  top: 6.5rem;
  display: grid;
  gap: 1.2rem;
}

.aside-block {
  padding-top: 0.8rem;
  border-top: 1px solid var(--line);
}

.aside-block strong,
.aside-block span {
  display: block;
}

.aside-block strong {
  color: var(--gold);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.aside-block span {
  margin-top: 0.35rem;
  color: var(--muted);
  font-size: 0.88rem;
}

.book-bridge {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 2rem;
  align-items: end;
  margin-top: 4rem;
  padding: 1.5rem;
  background: var(--gold);
  color: var(--ink);
}

.book-bridge h2 {
  max-width: 15ch;
  font-size: clamp(1.8rem, 3vw, 3rem);
}

.book-bridge p {
  max-width: 40rem;
  margin-top: 0.7rem;
  color: #4e4227;
}

.lesson-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 3.5rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--line);
}

.lesson-nav a {
  color: var(--paper-dim);
  text-decoration: none;
}

.lesson-nav a:hover,
.lesson-nav a:focus-visible {
  color: var(--gold);
}

.site-footer {
  padding-block: 1.3rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.78rem;
}

.site-footer-inner {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.site-footer a {
  color: var(--paper-dim);
  text-decoration: none;
}

.site-footer a:hover,
.site-footer a:focus-visible {
  color: var(--paper);
}

:focus-visible {
  outline: 2px solid var(--orange);
  outline-offset: 4px;
}

@media (max-width: 820px) {
  .course-nav {
    align-items: flex-start;
    flex-direction: column;
    padding-block: 1rem;
  }

  .course-nav-links {
    flex-wrap: wrap;
  }

  .course-hero,
  .lesson-layout {
    grid-template-columns: 1fr;
  }

  .lesson-aside {
    position: static;
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .course-teaser,
  .course-cta,
  .book-bridge {
    grid-template-columns: 1fr;
  }

  .course-cta .button,
  .book-bridge .button {
    justify-self: start;
  }
}

@media (max-width: 560px) {
  .container {
    width: min(calc(100% - 2rem), var(--max));
  }

  .brand-name {
    font-size: 0.98rem;
  }

  .course-nav-links {
    gap: 0.9rem;
    font-size: 0.8rem;
  }

  h1 {
    font-size: clamp(2.9rem, 15vw, 5rem);
  }

  .course-stats {
    grid-template-columns: 1fr;
  }

  .course-stat + .course-stat {
    padding-left: 0;
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  .lesson-index li {
    grid-template-columns: 2.5rem 1fr;
  }

  .lesson-index-link {
    grid-column: 2;
    justify-self: start;
  }

  .lesson-aside {
    grid-template-columns: 1fr;
  }

  .lesson-nav {
    align-items: flex-start;
    flex-direction: column;
  }
}

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

  *,
  *::before,
  *::after {
    transition-duration: 0.001ms !important;
  }
}