/* Quartet — shared design system */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300..700&family=JetBrains+Mono:wght@400;500&display=swap');

:root {
  --text-xs:   clamp(0.75rem,  0.7rem  + 0.25vw, 0.875rem);
  --text-sm:   clamp(0.875rem, 0.8rem  + 0.35vw, 1rem);
  --text-base: clamp(1rem,     0.95rem + 0.25vw, 1.125rem);
  --text-lg:   clamp(1.125rem, 1rem    + 0.75vw, 1.5rem);
  --text-xl:   clamp(1.5rem,   1.2rem  + 1.25vw, 2.25rem);
  --text-2xl:  clamp(2rem,     1.2rem  + 2.5vw,  3.5rem);
  --space-1: .25rem; --space-2: .5rem; --space-3: .75rem;
  --space-4: 1rem;   --space-5: 1.25rem; --space-6: 1.5rem;
  --space-8: 2rem;   --space-10: 2.5rem; --space-12: 3rem;
  --space-16: 4rem;  --space-20: 5rem;   --space-24: 6rem;
  --radius-sm: .375rem; --radius-md: .5rem;
  --radius-lg: .75rem;  --radius-xl: 1rem; --radius-full: 9999px;
  --transition: 180ms cubic-bezier(0.16, 1, 0.3, 1);
  --content-narrow: 640px;
  --content-default: 880px;
  --content-wide: 1200px;
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;
}

/* Dark mode (default) */
:root, [data-theme="dark"] {
  --color-bg:              #0f1117;
  --color-surface:         #161820;
  --color-surface-2:       #1c1e28;
  --color-divider:         #252830;
  --color-border:          #2e3040;
  --color-text:            #e2e4ec;
  --color-text-muted:      #868a9e;
  --color-text-faint:      #4a4d5e;
  --color-primary:         #4f98a3;
  --color-primary-hover:   #5fb0bc;
  --shadow-sm: 0 1px 2px oklch(0 0 0 / 0.25);
}

[data-theme="light"] {
  --color-bg:              #f7f6f2;
  --color-surface:         #fafaf7;
  --color-surface-2:       #ffffff;
  --color-divider:         #dcd9d4;
  --color-border:          #d0cdc8;
  --color-text:            #28251d;
  --color-text-muted:      #6e6b64;
  --color-text-faint:      #b0ada8;
  --color-primary:         #01696f;
  --color-primary-hover:   #0c4e54;
  --shadow-sm: 0 1px 2px oklch(0.2 0.01 80 / 0.06);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility; }
body {
  min-height: 100dvh;
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-bg);
  display: flex;
  flex-direction: column;
}
a { transition: color var(--transition); }
h1,h2,h3,h4 { text-wrap: balance; line-height: 1.15; }
p, li { text-wrap: pretty; }

/* Nav */
.nav {
  position: sticky; top: 0; z-index: 100;
  background: oklch(from var(--color-bg) l c h / 0.88);
  backdrop-filter: blur(20px) saturate(1.4);
  -webkit-backdrop-filter: blur(20px) saturate(1.4);
  border-bottom: 1px solid var(--color-divider);
}
.nav-inner {
  max-width: var(--content-wide);
  margin-inline: auto;
  padding: var(--space-4) var(--space-6);
  display: flex; align-items: center; justify-content: space-between; gap: var(--space-4);
}
.nav-logo { display: flex; align-items: center; gap: var(--space-3); text-decoration: none; color: var(--color-text); }
.nav-logo-text { font-size: var(--text-sm); font-weight: 600; letter-spacing: -0.01em; }
.nav-links { display: flex; align-items: center; gap: var(--space-6); }
.nav-links a { font-size: var(--text-sm); color: var(--color-text-muted); text-decoration: none; padding: var(--space-1) 0; }
.nav-links a:hover { color: var(--color-text); }
.nav-links a[aria-current="page"] { color: var(--color-primary); }
.theme-toggle {
  display: flex; align-items: center; justify-content: center;
  width: 36px; height: 36px; border-radius: var(--radius-md);
  color: var(--color-text-muted); border: 1px solid var(--color-border);
  cursor: pointer; background: none; font: inherit;
}
.theme-toggle:hover { color: var(--color-text); background: var(--color-surface); }

/* Footer */
footer {
  border-top: 1px solid var(--color-divider);
  padding: var(--space-10) var(--space-6);
  margin-top: auto;
}
.footer-inner {
  max-width: var(--content-wide);
  margin-inline: auto;
  display: flex; align-items: center; justify-content: space-between;
  gap: var(--space-6); flex-wrap: wrap;
}
.footer-brand { display: flex; align-items: center; gap: var(--space-3); }
.footer-brand-text { font-size: var(--text-sm); font-weight: 600; color: var(--color-text); }
.footer-links { display: flex; gap: var(--space-6); }
.footer-links a { font-size: var(--text-sm); color: var(--color-text-muted); text-decoration: none; }
.footer-links a:hover { color: var(--color-text); }
.footer-copy { font-size: var(--text-xs); color: var(--color-text-faint); }

@media (max-width: 768px) {
  .nav-links { display: none; }
  footer { padding: var(--space-8) var(--space-4); }
  .footer-inner { flex-direction: column; align-items: flex-start; gap: var(--space-4); }
}