:root {
  color-scheme: light dark;
  --color-bg: #ffffff;
  --color-surface: #f8fafc;
  --color-text: #0f172a;
  --color-muted: #475569;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-border: #e2e8f0;

  --container-max: 64rem;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-12: 3rem;
  --space-16: 4rem;

  --radius: 0.5rem;
  --shadow-focus: 0 0 0 3px rgba(37, 99, 235, 0.35);
}

@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #0b1220;
    --color-surface: #111a2e;
    --color-text: #e2e8f0;
    --color-muted: #94a3b8;
    --color-accent: #60a5fa;
    --color-accent-hover: #93c5fd;
    --color-border: #1e293b;
    --shadow-focus: 0 0 0 3px rgba(96, 165, 250, 0.4);
  }
}

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

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Ubuntu, sans-serif;
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

main {
  flex: 1 0 auto;
}

a {
  color: var(--color-accent);
  text-decoration: none;
}

a:hover,
a:focus-visible {
  color: var(--color-accent-hover);
  text-decoration: underline;
}

a:focus-visible,
button:focus-visible {
  outline: none;
  box-shadow: var(--shadow-focus);
  border-radius: var(--radius);
}

h1, h2, h3 {
  line-height: 1.2;
  margin: 0 0 var(--space-4);
}

h1 { font-size: clamp(2rem, 1.5rem + 2vw, 3rem); }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }

p {
  margin: 0 0 var(--space-4);
}

code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9em;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 0.25rem;
  padding: 0.1em 0.35em;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--space-6);
}

/* Skip link — visually hidden until focused */
.skip-link {
  position: absolute;
  left: var(--space-4);
  top: var(--space-4);
  background: var(--color-accent);
  color: #fff;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius);
  transform: translateY(-200%);
  transition: transform 150ms ease;
  z-index: 10;
}

.skip-link:focus {
  transform: translateY(0);
  color: #fff;
  text-decoration: none;
}

/* Header */
.site-header {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
  padding-block: var(--space-4);
  flex-wrap: wrap;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  color: var(--color-text);
  font-weight: 600;
}

.brand:hover,
.brand:focus-visible {
  color: var(--color-text);
  text-decoration: none;
}

.brand__mark {
  width: 1.5rem;
  height: 1.5rem;
  color: var(--color-accent);
}

.brand__name {
  font-size: 1.125rem;
}

.site-nav {
  display: flex;
  gap: var(--space-6);
}

.site-nav a {
  color: var(--color-muted);
  font-weight: 500;
}

.site-nav a:hover,
.site-nav a:focus-visible {
  color: var(--color-text);
  text-decoration: none;
}

.site-nav a[aria-current="page"] {
  color: var(--color-text);
}

/* Hero */
.hero {
  padding-block: var(--space-16) var(--space-12);
  text-align: left;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: var(--space-2);
}

.lead {
  font-size: 1.15rem;
  color: var(--color-muted);
  max-width: 40rem;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin-top: var(--space-6);
}

.btn {
  display: inline-block;
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius);
  font-weight: 600;
  border: 1px solid transparent;
  transition: background-color 150ms ease, color 150ms ease, border-color 150ms ease;
}

.btn--primary {
  background: var(--color-accent);
  color: #fff;
}

.btn--primary:hover,
.btn--primary:focus-visible {
  background: var(--color-accent-hover);
  color: #fff;
  text-decoration: none;
}

.btn--ghost {
  background: transparent;
  color: var(--color-text);
  border-color: var(--color-border);
}

.btn--ghost:hover,
.btn--ghost:focus-visible {
  border-color: var(--color-accent);
  color: var(--color-accent);
  text-decoration: none;
}

/* Features grid */
.features {
  display: grid;
  gap: var(--space-6);
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  padding-block: var(--space-8) var(--space-16);
}

.feature {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-6);
}

.feature h2 {
  margin-top: 0;
  font-size: 1.125rem;
}

.feature p {
  color: var(--color-muted);
  margin: 0;
}

/* Prose (content pages) */
.prose {
  padding-block: var(--space-12) var(--space-16);
  max-width: 42rem;
}

.prose p {
  color: var(--color-text);
}

.prose .lead {
  color: var(--color-muted);
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
  font-size: 0.9rem;
  color: var(--color-muted);
}

.site-footer__inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-2);
  padding-block: var(--space-6);
}

.site-footer p {
  margin: 0;
}