:root {
  --bg: #f6f8ff;
  --bg-strong: #e6eaff;
  --surface: rgba(255, 255, 255, 0.92);
  --surface-strong: #ffffff;
  --surface-tint: rgba(248, 250, 255, 0.96);
  --text: #212553;
  --text-soft: #5a628e;
  --line: rgba(91, 101, 179, 0.14);
  --brand: #3f61d7;
  --brand-dark: #2b3c8f;
  --accent: #7f57d9;
  --accent-soft: #ebe1ff;
  --success: #e5eeff;
  --shadow: 0 18px 38px rgba(63, 97, 215, 0.09);
  --radius: 24px;
  --radius-sm: 16px;
  --wrap: min(1240px, calc(100vw - 2.5rem));
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--text);
  font-family: "Source Serif 4", Georgia, serif;
  background:
    radial-gradient(circle at top left, rgba(127, 87, 217, 0.14), transparent 22%),
    radial-gradient(circle at top right, rgba(63, 97, 215, 0.12), transparent 24%),
    linear-gradient(180deg, #fcfdff 0%, var(--bg) 54%, #eff3ff 100%);
}

a {
  color: var(--brand-dark);
}

img {
  max-width: 100%;
}

code,
pre,
.meta,
.button,
.brand,
.site-nav a,
.module-link,
.course-menu a,
.mini-label {
  font-family: "Space Grotesk", "Helvetica Neue", sans-serif;
}

code {
  padding: 0.1rem 0.35rem;
  border-radius: 0.45rem;
  background: rgba(72, 87, 216, 0.1);
  font-size: 0.92em;
}

pre {
  overflow-x: auto;
  position: relative;
  margin: 1.15rem 0 0;
  padding: 1.15rem 1.2rem;
  border: 1px solid rgba(125, 144, 255, 0.16);
  border-radius: 18px;
  background:
    radial-gradient(circle at top right, rgba(115, 92, 255, 0.18), transparent 28%),
    linear-gradient(180deg, #101528 0%, #171d33 100%);
  color: #eef2ff;
  line-height: 1.6;
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.04),
    0 18px 32px rgba(11, 17, 39, 0.18);
}

pre code {
  display: block;
  padding: 0;
  background: transparent;
  color: inherit;
  font-size: 0.95rem;
}

pre::before {
  content: "";
  position: absolute;
  top: 0.9rem;
  right: 1rem;
  width: 0.7rem;
  height: 0.7rem;
  border-radius: 999px;
  background: #ffb347;
  box-shadow:
    -1.2rem 0 0 #ff6b6b,
    -0.6rem 0 0 #6ee7b7;
  opacity: 0.9;
}

.hljs {
  background: transparent !important;
  color: inherit !important;
}

.wrap {
  width: var(--wrap);
  margin: 0 auto;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: -3rem;
  z-index: 100;
  padding: 0.75rem 1rem;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--brand), var(--accent));
  color: #fff;
  font-family: "Space Grotesk", "Helvetica Neue", sans-serif;
  font-weight: 700;
  text-decoration: none;
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(14px);
  background: rgba(252, 253, 255, 0.92);
  border-bottom: 1px solid rgba(63, 97, 215, 0.08);
}

.site-header .wrap,
.site-footer .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-header .wrap {
  padding: 0.85rem 0;
}

.header-shell {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  width: 100%;
}

.brand {
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-decoration: none;
  text-transform: uppercase;
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  align-items: center;
}

.site-nav a {
  font-size: 0.95rem;
  text-decoration: none;
}

.site-nav .nav-link {
  padding: 0.45rem 0.7rem;
  border-radius: 999px;
  color: var(--text-soft);
  transition: background-color 150ms ease, color 150ms ease, transform 150ms ease;
}

.site-nav .nav-link:hover,
.site-nav .nav-link:focus-visible {
  background: rgba(63, 97, 215, 0.08);
  color: var(--brand-dark);
  transform: translateY(-1px);
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.6rem 0.95rem;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--brand), var(--accent));
  color: #f9f7ff;
  font-weight: 700;
  text-decoration: none;
  box-shadow: 0 10px 20px rgba(63, 97, 215, 0.14);
}

.hero {
  padding: 5rem 0 3.5rem;
}

.hero-grid,
.split-grid,
.course-layout,
.page-layout,
.lesson-shell,
.course-outline {
  display: grid;
  gap: 1.5rem;
}

.hero-grid {
  grid-template-columns: minmax(0, 1.5fr) minmax(320px, 0.9fr);
  align-items: stretch;
}

.eyebrow,
.module-index,
.page-kicker,
.mini-label {
  margin: 0 0 0.75rem;
  color: var(--brand);
  font-size: 0.86rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1,
h2,
h3,
h4 {
  margin: 0;
  line-height: 1;
}

h1 {
  max-width: 11ch;
  font-size: clamp(3rem, 7vw, 5.8rem);
}

h2 {
  font-size: clamp(2rem, 4vw, 3.2rem);
}

h3 {
  font-size: 1.5rem;
}

h4 {
  font-size: 1.08rem;
}

p,
li {
  color: var(--text-soft);
  font-size: 1.06rem;
  line-height: 1.72;
}

ul,
ol {
  padding-left: 1.2rem;
}

.lead {
  max-width: 62ch;
  font-size: 1.2rem;
}

.hero-copy,
.hero-card,
.module-card,
.panel,
.callout,
.course-menu,
.mini-card,
.quick-links a {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.hero-copy,
.hero-card,
.module-card,
.panel,
.callout,
.course-menu,
.mini-card {
  background: var(--surface);
}

.hero-copy {
  padding: 2.4rem;
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.92), rgba(247, 249, 255, 0.96)),
    linear-gradient(135deg, rgba(63, 97, 215, 0.06), rgba(127, 87, 217, 0.08));
}

.hero-card,
.panel,
.callout,
.course-menu,
.mini-card {
  padding: 1.4rem;
}

.hero-card {
  background:
    radial-gradient(circle at top right, rgba(127, 87, 217, 0.12), transparent 38%),
    radial-gradient(circle at bottom left, rgba(101, 180, 255, 0.08), transparent 34%),
    var(--surface-tint);
}

.hero-actions,
.button-row,
.quick-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
}

.hero-actions {
  margin-top: 2rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.9rem 1.25rem;
  border: 1px solid transparent;
  border-radius: 999px;
  font-size: 0.95rem;
  font-weight: 700;
  text-decoration: none;
}

.button-primary {
  background: linear-gradient(135deg, var(--brand), var(--accent));
  color: #f9f7ff;
}

.button-secondary {
  border-color: var(--line);
  background: rgba(255, 255, 255, 0.76);
}

.section {
  padding: 3rem 0 4.75rem;
}

.section-heading {
  max-width: 48rem;
  margin-bottom: 1.75rem;
}

.split-grid {
  grid-template-columns: minmax(0, 1.3fr) minmax(280px, 0.9fr);
  align-items: start;
}

.module-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.6rem;
}

.module-card {
  padding: 1.7rem;
}

.module-card p {
  margin-bottom: 1rem;
}

.module-link {
  font-weight: 700;
  text-decoration-thickness: 2px;
}

.course-outline {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.mini-card {
  min-height: 100%;
}

.course-layout {
  grid-template-columns: minmax(250px, 320px) minmax(0, 1fr);
  align-items: start;
}

.page-layout {
  grid-template-columns: minmax(0, 1fr) minmax(280px, 320px);
  align-items: start;
}

.course-menu {
  position: sticky;
  top: 5.5rem;
  background: rgba(255, 255, 255, 0.72);
  box-shadow: none;
  backdrop-filter: blur(10px);
}

.course-menu h2,
.page-sidebar h2 {
  margin-bottom: 0.8rem;
  font-size: 1.35rem;
}

.course-menu ol {
  margin: 0;
  padding-left: 1rem;
  display: grid;
  gap: 0.9rem;
}

.course-menu a {
  text-decoration: none;
  font-weight: 700;
}

.course-menu p {
  margin: 0.2rem 0 0;
  font-size: 0.93rem;
  line-height: 1.5;
}

.course-menu .active {
  color: var(--brand);
}

.quick-links {
  margin-top: 1rem;
}

.quick-links a {
  flex: 1 1 220px;
  padding: 1rem 1.1rem;
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.88), rgba(243, 246, 255, 0.94));
  text-decoration: none;
}

.page-main {
  padding: 3.6rem 0 5.6rem;
}

.lesson-shell {
  grid-template-columns: minmax(250px, 320px) minmax(0, 1fr);
  align-items: start;
}

.lesson-content {
  display: grid;
  gap: 1.6rem;
}

.page-hero {
  padding: 2.15rem;
  border: 1px solid var(--line);
  border-radius: calc(var(--radius) + 4px);
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.96), rgba(246, 248, 255, 0.98)),
    radial-gradient(circle at top right, rgba(63, 97, 215, 0.1), transparent 35%),
    radial-gradient(circle at bottom left, rgba(127, 87, 217, 0.06), transparent 35%);
  box-shadow: var(--shadow);
}

.page-hero h1 {
  max-width: none;
  font-size: clamp(2.8rem, 6vw, 4.8rem);
}

.meta-row,
.tag-row,
.nav-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.meta,
.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.45rem 0.75rem;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.75);
  font-size: 0.9rem;
}

.panel h2 {
  margin-bottom: 0.95rem;
  font-size: 1.6rem;
}

.panel h3 {
  margin: 1.25rem 0 0.6rem;
  font-size: 1.3rem;
}

.panel h4 {
  margin: 1rem 0 0.35rem;
}

.panel > :first-child {
  margin-top: 0;
}

.step-list {
  margin: 0;
  padding-left: 1.15rem;
}

.step-list li {
  margin-bottom: 0.9rem;
  padding: 0.95rem 1rem 0.95rem 0.8rem;
  border: 1px solid rgba(91, 101, 179, 0.08);
  border-radius: 18px;
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.92), rgba(245, 247, 255, 0.96));
}

.callout {
  background:
    linear-gradient(135deg, rgba(248, 247, 255, 0.98), rgba(237, 231, 255, 0.9));
}

.callout-success {
  background:
    linear-gradient(135deg, rgba(245, 248, 255, 0.96), rgba(223, 232, 255, 0.9));
}

.callout-warning {
  background:
    linear-gradient(135deg, rgba(245, 244, 255, 0.96), rgba(214, 230, 255, 0.9));
}

.callout h3 {
  margin-bottom: 0.6rem;
}

.page-sidebar {
  display: grid;
  gap: 1.2rem;
}

.resource-list,
.check-list {
  margin: 0;
  padding-left: 1.2rem;
}

.resource-list li + li,
.check-list li + li {
  margin-top: 0.6rem;
}

.resource-list li {
  padding: 0.2rem 0;
}

.nav-row {
  justify-content: space-between;
  margin-top: 1rem;
}

.nav-row a {
  flex: 1 1 220px;
  padding: 1rem 1.05rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.92), rgba(243, 246, 255, 0.96));
  text-decoration: none;
}

.site-footer {
  padding: 1.25rem 0 2.5rem;
}

.site-footer p {
  margin: 0;
  font-size: 0.95rem;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
}

.footer-links a {
  font-family: "Space Grotesk", "Helvetica Neue", sans-serif;
  font-size: 0.92rem;
  text-decoration: none;
}

@media (max-width: 980px) {
  .hero-grid,
  .split-grid,
  .course-layout,
  .page-layout,
  .lesson-shell,
  .course-outline,
  .module-grid {
    grid-template-columns: 1fr;
  }

  .course-menu {
    position: static;
  }

  .hero,
  .section,
  .page-main {
    padding-top: 3.5rem;
  }
}

@media (max-width: 720px) {
  .site-header .wrap,
  .site-footer .wrap {
    flex-direction: column;
    align-items: flex-start;
  }

  .header-shell {
    flex-direction: column;
    align-items: flex-start;
  }

  h1 {
    font-size: clamp(2.6rem, 16vw, 4rem);
  }

  .page-hero,
  .panel,
  .course-menu,
  .hero-copy,
  .hero-card,
  .module-card,
  .callout,
  .mini-card {
    padding: 1.2rem;
  }
}