:root {
  --bg: #0c110e;
  --surface: #131a16;
  --line: #24302a;
  --text: #dce8de;
  --muted: #8b9c90;
  --accent: #7cf27a;
  --accent-ink: #0c110e;
  --amber: #f5c800;
  --pixel: "Silkscreen", ui-monospace, monospace;
  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --max: 1040px;
  color-scheme: dark;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--mono);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
}

a:focus-visible,
.btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

main,
.top,
.bottom {
  width: min(var(--max), 100% - 32px);
  margin-inline: auto;
}

/* Header */

.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding-block: 20px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--pixel);
  font-size: 18px;
  text-decoration: none;
}

.brand em,
h1 span {
  font-style: normal;
  color: var(--accent);
}

.brand-dino {
  width: 28px;
  height: 28px;
  fill: var(--accent);
}

/* Selectors can't reach inside <use> copies, so the runner switches the
   leg animation on through inherited custom properties. */
.leg-a {
  animation: var(--leg-a, none);
}

.leg-b {
  opacity: 0;
  animation: var(--leg-b, none);
}

@keyframes leg-a {
  50% {
    opacity: 0;
  }
}

@keyframes leg-b {
  50% {
    opacity: 1;
  }
}

.nav {
  display: flex;
  gap: 20px;
  font-size: 14px;
}

.nav a {
  color: var(--muted);
  text-decoration: none;
}

.nav a:hover {
  color: var(--text);
}

/* Hero */

.hero {
  padding-block: 64px 32px;
}

.eyebrow {
  color: var(--muted);
  font-size: 13px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1 {
  font-family: var(--pixel);
  font-weight: 700;
  font-size: clamp(44px, 11vw, 112px);
  line-height: 1;
  margin-block: 12px 20px;
  letter-spacing: -0.02em;
}

.tagline {
  font-size: clamp(16px, 2.4vw, 20px);
  color: var(--muted);
  max-width: 44ch;
}

.tagline strong {
  color: var(--text);
}

.actions,
.links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.btn {
  display: inline-block;
  padding: 10px 16px;
  border: 1px solid var(--line);
  border-radius: 4px;
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  transition:
    border-color 0.15s,
    background 0.15s;
}

.btn:hover {
  border-color: var(--accent);
}

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
}

.btn-primary:hover {
  background: #a3f7a1;
}

/* Runner: dino jumps over code glyphs scrolling along a line of code */

.runner {
  position: relative;
  height: 140px;
  margin-top: 56px;
  overflow: hidden;
  border-bottom: 2px solid var(--line);
}

.runner-dino {
  position: absolute;
  left: 12%;
  bottom: 22px;
  width: 57px;
  height: 57px;
  fill: var(--accent);
  animation: jump 1s infinite;
  --leg-a: leg-a 0.24s steps(1) infinite;
  --leg-b: leg-b 0.24s steps(1) infinite;
}

.obstacles span {
  position: absolute;
  bottom: 22px;
  left: 100%;
  font-family: var(--pixel);
  font-size: 22px;
  color: var(--amber);
  animation: scroll-obstacle 3s linear infinite;
}

.obstacles span:nth-child(2) {
  animation-delay: -1s;
}

.obstacles span:nth-child(3) {
  animation-delay: -2s;
}

.ground {
  position: absolute;
  bottom: 0;
  left: 0;
  white-space: nowrap;
  font-size: 12px;
  color: #3d4d44;
}

.ground span {
  display: inline-block;
  animation: scroll-ground 12s linear infinite;
}

@keyframes scroll-obstacle {
  from {
    left: 100%;
  }
  to {
    left: -10%;
  }
}

@keyframes scroll-ground {
  to {
    transform: translateX(-50%);
  }
}

/* Each obstacle reaches the dino 0.4s into every 1s cycle. */
@keyframes jump {
  0%,
  15%,
  65%,
  100% {
    transform: translateY(0);
  }
  40% {
    transform: translateY(-62px);
  }
}

/* Sections */

section + section {
  border-top: 1px solid var(--line);
}

.about,
.expeditions {
  padding-block: 64px;
}

h2 {
  font-family: var(--pixel);
  font-weight: 400;
  font-size: clamp(20px, 3vw, 26px);
  margin-bottom: 24px;
}

.prompt {
  color: var(--accent);
}

.lede {
  max-width: 64ch;
  color: var(--muted);
}

.lede strong {
  color: var(--text);
}

.facts {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  margin-top: 32px;
}

.facts li {
  padding: 20px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 6px;
}

.facts h3 {
  font-family: var(--pixel);
  font-weight: 400;
  font-size: 15px;
  color: var(--accent);
  margin-bottom: 8px;
}

.facts p {
  font-size: 14px;
  color: var(--muted);
}

/* Expeditions */

.expedition {
  padding: 24px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 6px;
}

.expedition + .expedition {
  margin-top: 16px;
}

.expedition.is-latest {
  border-color: var(--accent);
}

.expedition header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 16px;
}

.tag {
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--amber);
}

.year {
  font-family: var(--pixel);
  font-size: clamp(32px, 6vw, 48px);
  line-height: 1;
}

.expedition dl {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px 24px;
}

.expedition dt {
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.expedition dd {
  font-size: 15px;
}

.expedition .links {
  margin-top: 20px;
}

.next {
  margin-top: 24px;
  padding: 16px 20px;
  border: 1px dashed var(--line);
  border-radius: 6px;
  color: var(--muted);
  font-size: 14px;
}

.next a {
  color: var(--accent);
}

.blink {
  color: var(--accent);
  animation: blink 1s steps(1) infinite;
}

@keyframes blink {
  50% {
    opacity: 0;
  }
}

/* Footer */

.bottom {
  padding-block: 32px 48px;
  border-top: 1px solid var(--line);
  font-size: 13px;
  color: var(--muted);
}

.foot-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
  margin-bottom: 12px;
}

.foot-links a {
  text-decoration: none;
}

.foot-links a:hover {
  color: var(--text);
}

@media (max-width: 560px) {
  .nav {
    gap: 14px;
    font-size: 13px;
  }

  .brand span {
    display: none;
  }

  .hero {
    padding-top: 40px;
  }
}

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

  .runner-dino {
    animation: none;
    --leg-a: none;
    --leg-b: none;
  }

  .obstacles span,
  .ground span,
  .blink {
    animation: none;
  }

  .obstacles span:nth-child(1) {
    left: 40%;
  }

  .obstacles span:nth-child(2) {
    left: 65%;
  }

  .obstacles span:nth-child(3) {
    left: 88%;
  }
}