:root {
  --clr-primary-200: 219 255 0;
  --clr-primary-300: 0 232 135;
  --clr-primary-400: 0 224 243;
  --clr-primary-500: 0 196 253;
  --bg: 255 255 255;
  --text: 31 41 55;
  --muted: 75 85 99;
  --border: 209 213 219;
}

html.dark {
  --bg: 14 17 17;
  --text: 243 244 246;
  --muted: 156 163 175;
  --border: 75 85 99;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
}

body {
  background: rgb(var(--bg));
  color: rgb(var(--text));
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, Roboto, "Noto Sans SC", sans-serif;
  transition: background-color .2s ease, color .2s ease;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.layout {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 1.5rem;
  width: 100%;
}

.top-bar {
  height: 4px;
  background: linear-gradient(to right, rgb(var(--clr-primary-200)), rgb(var(--clr-primary-300)), rgb(var(--clr-primary-400)));
}

header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgb(var(--bg));
  border-bottom: 1px solid transparent;
}

nav.layout {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
}

nav ul {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: .95rem;
}

nav a {
  color: rgb(var(--text));
  text-decoration: none;
  font-weight: 500;
  transition: color .15s ease;
}

nav a:hover,
nav a.active {
  background: linear-gradient(to top right, rgb(var(--clr-primary-300)), rgb(var(--clr-primary-400)));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.theme-toggle {
  border: 1px solid rgb(var(--border));
  background: transparent;
  color: rgb(var(--text));
  border-radius: .5rem;
  padding: .4rem .6rem;
  cursor: pointer;
  line-height: 1;
  font-size: 1.1rem;
}

.theme-toggle:hover {
  border-color: rgb(var(--clr-primary-300));
  color: rgb(var(--clr-primary-300));
}

main {
  flex: 1;
}

.hero {
  min-height: calc(100vh - 8rem);
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 3rem 0;
}

.hero h2 {
  font-size: 1.75rem;
  margin: 0 0 .25rem;
  font-weight: 600;
}

.hero h1 {
  font-size: 2.75rem;
  margin: 0 0 1rem;
  font-weight: 700;
}

.gradient-text {
  background: linear-gradient(to top right, rgb(var(--clr-primary-300)), rgb(var(--clr-primary-400)));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero p.tagline {
  color: rgb(var(--muted));
  font-size: 1.1rem;
  max-width: 40rem;
  margin: 0 0 2rem;
}

.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.btn {
  position: relative;
  display: inline-flex;
  border-radius: .375rem;
  padding: .6rem 1.25rem;
  font-weight: 700;
  border: 1px solid rgb(var(--border));
  background: rgb(var(--bg));
  color: rgb(var(--text));
  text-decoration: none;
  transition: transform .15s ease;
}

.btn:hover {
  transform: scale(1.03);
  border-color: rgb(var(--clr-primary-300));
}

.btn-glow {
  position: relative;
}

.btn-glow::before {
  content: "";
  position: absolute;
  inset: -2px;
  border-radius: .5rem;
  background: linear-gradient(to right, rgb(var(--clr-primary-300)), rgb(var(--clr-primary-400)));
  filter: blur(6px);
  opacity: .5;
  z-index: -1;
  transition: opacity .3s ease;
}

.btn-glow:hover::before {
  opacity: .85;
}

.social-row {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  margin-top: 1.5rem;
  font-size: .95rem;
}

.social-row a {
  color: rgb(var(--muted));
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: .4rem;
}

.social-row a:hover {
  color: rgb(var(--text));
}

.page h2.eyebrow {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 0;
}

.page {
  padding: 4rem 0;
  min-height: calc(100vh - 8rem);
}

.page h1 {
  font-size: 2.25rem;
  margin-top: .25rem;
}

.prose {
  color: rgb(var(--text));
  line-height: 1.8;
}

.prose p {
  margin: 1rem 0;
}

.back-link {
  display: inline-block;
  margin-top: 2rem;
  color: rgb(var(--muted));
  text-decoration: none;
}

.back-link:hover {
  color: rgb(var(--clr-primary-300));
}

footer {
  padding: 1.5rem 0 2rem;
  border-top: 1px solid rgb(var(--border));
  margin-top: 1rem;
}

footer .layout {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: .5rem;
  text-align: center;
}

footer p {
  color: rgb(var(--muted));
  font-size: .85rem;
  margin: 0;
}

@media (max-width: 640px) {
  .hero h1 { font-size: 2.1rem; }
  nav ul { gap: .75rem; font-size: .85rem; }
}