:root {
  color-scheme: light;
  --paper: #f7f3ea;
  --paper-strong: #ede4d1;
  --surface: #fffdf8;
  --ink: #17202a;
  --muted: #596272;
  --line: #d8cfbf;
  --oxford: #002147;
  --crimson: #b31b34;
  --blue: #346b8d;
  --green: #315f55;
  --gold: #c4912f;
  --shadow: 0 24px 60px rgba(23, 32, 42, 0.12);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background:
    radial-gradient(circle at top left, rgba(179, 27, 52, 0.12), transparent 34rem),
    linear-gradient(180deg, var(--paper), #fbfaf6 42rem);
  color: var(--ink);
  line-height: 1.58;
}

a {
  color: inherit;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: grid;
  grid-template-columns: minmax(220px, 360px) 1fr;
  gap: 24px;
  align-items: center;
  padding: 14px clamp(18px, 4vw, 52px);
  border-bottom: 1px solid rgba(23, 32, 42, 0.12);
  background: rgba(247, 243, 234, 0.94);
  backdrop-filter: blur(18px);
}

.brand {
  color: var(--oxford);
  font-weight: 800;
  text-decoration: none;
}

nav {
  display: flex;
  gap: 10px;
  justify-content: flex-end;
  overflow-x: auto;
  padding-bottom: 2px;
  color: var(--muted);
  font-size: 0.9rem;
  white-space: nowrap;
}

nav a {
  padding: 8px 10px;
  border-radius: 999px;
  text-decoration: none;
}

nav a:hover,
nav a:focus {
  background: rgba(0, 33, 71, 0.08);
  color: var(--oxford);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 0.82fr);
  gap: clamp(28px, 5vw, 72px);
  align-items: center;
  min-height: calc(100vh - 64px);
  padding: clamp(54px, 8vw, 110px) clamp(20px, 5vw, 72px);
}

.deck-source {
  color: var(--crimson);
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

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

h1 {
  max-width: 940px;
  margin-bottom: 24px;
  color: var(--oxford);
  font-size: clamp(3rem, 7.8vw, 7.2rem);
  line-height: 0.96;
  letter-spacing: 0;
}

.hero p:not(.deck-source) {
  max-width: 760px;
  color: #394553;
  font-size: clamp(1.15rem, 2vw, 1.55rem);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 13px 18px;
  border: 1px solid transparent;
  border-radius: 8px;
  font-weight: 800;
  text-decoration: none;
}

.button.primary {
  background: var(--oxford);
  color: #fffdf8;
}

.button.secondary {
  border-color: rgba(0, 33, 71, 0.28);
  background: rgba(255, 253, 248, 0.72);
  color: var(--oxford);
}

.hero-visual {
  margin: 0;
  border: 1px solid rgba(0, 33, 71, 0.14);
  border-radius: 20px;
  overflow: hidden;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.hero-visual img {
  display: block;
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
}

.guide-shell {
  display: grid;
  grid-template-columns: 240px minmax(0, 1fr);
  gap: clamp(22px, 4vw, 46px);
  padding: 0 clamp(20px, 5vw, 72px) clamp(60px, 8vw, 110px);
}

.side-nav {
  position: sticky;
  top: 88px;
  align-self: start;
  display: grid;
  gap: 6px;
  max-height: calc(100vh - 108px);
  overflow: auto;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: rgba(255, 253, 248, 0.78);
}

.side-nav p {
  margin-bottom: 8px;
  color: var(--crimson);
  font-size: 0.8rem;
  font-weight: 850;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.side-nav a {
  padding: 7px 8px;
  border-radius: 8px;
  color: var(--muted);
  font-size: 0.9rem;
  text-decoration: none;
}

.side-nav a:hover {
  background: rgba(0, 33, 71, 0.08);
  color: var(--oxford);
}

.activity-flow {
  display: grid;
  gap: 18px;
}

.activity-card {
  position: relative;
  padding: clamp(24px, 4vw, 42px);
  border: 1px solid rgba(0, 33, 71, 0.12);
  border-radius: 18px;
  background: var(--surface);
  box-shadow: 0 14px 36px rgba(23, 32, 42, 0.07);
}

.activity-card::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 6px;
  border-radius: 18px 0 0 18px;
  background: linear-gradient(180deg, var(--oxford), var(--crimson));
}

.resource-card {
  background: #f4efe3;
}

h2 {
  max-width: 760px;
  margin-bottom: 14px;
  color: var(--oxford);
  font-size: clamp(2rem, 4vw, 3.7rem);
  line-height: 1.02;
  letter-spacing: 0;
}

h3 {
  margin-top: 22px;
  margin-bottom: 8px;
  color: var(--oxford);
  font-size: 1.18rem;
  line-height: 1.22;
}

.activity-card > p,
.activity-card li,
blockquote {
  max-width: 850px;
}

.activity-card p,
.activity-card li {
  color: #3d4755;
}

.meta-line {
  margin-bottom: 8px;
}

.meta-line strong {
  display: inline-block;
  min-width: 58px;
  color: var(--crimson);
}

ul,
ol {
  padding-left: 1.25rem;
}

li + li {
  margin-top: 6px;
}

blockquote {
  margin: 18px 0;
  padding: 18px 20px;
  border-left: 5px solid var(--gold);
  background: #fff8e7;
  color: #2d3540;
  font-weight: 650;
}

code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 0.94em;
}

p code,
li code,
h2 code {
  padding: 0.12em 0.32em;
  border-radius: 5px;
  background: rgba(0, 33, 71, 0.08);
  color: var(--oxford);
}

.copy-block {
  position: relative;
  max-width: 900px;
  margin: 18px 0 24px;
}

.copy-block pre {
  margin: 0;
  overflow-x: auto;
  padding: 20px 86px 20px 20px;
  border: 1px solid rgba(0, 33, 71, 0.18);
  border-radius: 12px;
  background: #121a24;
  color: #fffdf8;
  font-size: 0.92rem;
  line-height: 1.55;
}

.copy-button {
  position: absolute;
  top: 10px;
  right: 10px;
  min-height: 34px;
  padding: 7px 11px;
  border: 1px solid rgba(255, 253, 248, 0.28);
  border-radius: 8px;
  background: rgba(255, 253, 248, 0.12);
  color: #fffdf8;
  font: inherit;
  font-size: 0.82rem;
  font-weight: 800;
  cursor: pointer;
}

.copy-button:hover {
  background: rgba(255, 253, 248, 0.22);
}

.activity-card a {
  color: var(--blue);
  font-weight: 720;
}

@media (max-width: 980px) {
  .site-header {
    grid-template-columns: 1fr;
  }

  nav {
    justify-content: flex-start;
  }

  .hero {
    grid-template-columns: 1fr;
    min-height: auto;
  }

  .guide-shell {
    grid-template-columns: 1fr;
  }

  .side-nav {
    position: static;
    max-height: none;
  }
}

@media (max-width: 640px) {
  .hero {
    padding-top: 42px;
  }

  .hero-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .button {
    width: 100%;
  }

  .activity-card {
    border-radius: 12px;
  }

  .copy-block pre {
    padding-right: 20px;
    padding-top: 54px;
  }
}