/* ─── Paper Design System ─── */
/* Minimal, clean, print-inspired. Typography-driven hierarchy. */

:root {
  --color-ink: #111111;
  --color-ink-light: #555555;
  --color-ink-muted: #999999;
  --color-paper: #FDFCFA;
  --color-paper-warm: #F7F6F3;
  --color-white: #FFFFFF;
  --color-accent: #29A9E1;
  --color-accent-hover: #1E8DBF;
  --color-rule: #E5E3DF;
  --color-rule-dark: #2A2A2A;

  --font-display: 'Montserrat', sans-serif;
  --font-body: 'Roboto', sans-serif;
  --font-mono: 'PT Mono', monospace;

  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;
  --space-4xl: 96px;
}

/* ─── Base ─── */
body {
  font-family: var(--font-body);
  font-weight: 400;
  font-size: 16px;
  line-height: 1.65;
  color: var(--color-ink);
  background-color: var(--color-paper);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ─── Typography ─── */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--color-ink);
  letter-spacing: -0.02em;
  line-height: 1.15;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color 0.15s ease;
}

/* ─── Navigation ─── */
.nav-paper {
  background: var(--color-paper);
  border-bottom: 1px solid var(--color-rule);
}

/* ─── Horizontal rule ─── */
.rule {
  border: none;
  border-top: 1px solid var(--color-rule);
}
.rule-dark {
  border: none;
  border-top: 1px solid var(--color-rule-dark);
}

/* ─── Cards ─── */
.card-paper {
  background: var(--color-white);
  border: 1px solid var(--color-rule);
  border-radius: 2px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.card-paper:hover {
  border-color: var(--color-ink-muted);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.04);
}

.card-dark {
  background: #1A1A1A;
  border: 1px solid var(--color-rule-dark);
  border-radius: 2px;
  transition: border-color 0.2s ease;
}
.card-dark:hover {
  border-color: #444;
}

/* ─── Labels ─── */
.label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}
.label-accent {
  color: var(--color-accent);
}

/* ─── Sunsetted ─── */
.sunsetted {
  opacity: 0.45;
  transition: opacity 0.2s ease;
}
.sunsetted:hover {
  opacity: 0.65;
}

/* ─── Footer ─── */
.footer-dark {
  background: var(--color-ink);
  color: #888;
}

/* ─── Accent underline ─── */
.accent-underline {
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-underline-offset: 4px;
  text-decoration-thickness: 2px;
}

/* ─── Button ─── */
.btn-primary {
  display: inline-flex;
  align-items: center;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 14px;
  letter-spacing: 0.01em;
  padding: 12px 28px;
  background: var(--color-ink);
  color: var(--color-white);
  border: none;
  border-radius: 2px;
  cursor: pointer;
  transition: background 0.15s ease;
}
.btn-primary:hover {
  background: #333;
  color: var(--color-white);
}

.btn-outline {
  display: inline-flex;
  align-items: center;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 14px;
  letter-spacing: 0.01em;
  padding: 11px 28px;
  background: transparent;
  color: var(--color-ink);
  border: 1px solid var(--color-rule);
  border-radius: 2px;
  cursor: pointer;
  transition: border-color 0.15s ease;
}
.btn-outline:hover {
  border-color: var(--color-ink);
  color: var(--color-ink);
}

/* ─── Project number ─── */
.project-num {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-ink-muted);
  min-width: 28px;
}

/* ─── Responsive ─── */
@media (max-width: 640px) {
  :root {
    --space-3xl: 48px;
    --space-4xl: 64px;
  }
}