/* ==========================================================================
   base.css — reset, base typography, primitives, accessibility.
   ========================================================================== */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  font-family: var(--font-display);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  font-weight: 400;
  background: var(--color-void);
  color: var(--color-chalk);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

img, svg { display: block; max-width: 100%; }
img { height: auto; }
ul { list-style: none; padding: 0; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }
input, select, textarea { font: inherit; color: inherit; }

::selection { background: var(--color-chalk); color: var(--color-void); }

/* --- Fixed noise-grain overlay: the only decoration in the system --- */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  z-index: var(--z-grain);
  pointer-events: none;
  opacity: 0.07;
  mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='180' height='180'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.82' numOctaves='2' stitchTiles='stitch'/%3E%3CfeColorMatrix type='saturate' values='0'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}
@media (prefers-reduced-motion: reduce) { body::after { opacity: 0.05; } }

/* --- Layout primitives --- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.section { position: relative; padding-block: var(--space-section); }

/* Theme inversion: sections own their palette (The Inversion Rule) */
.is-dark  { background: var(--color-void);     color: var(--color-chalk); }
.is-light { background: var(--color-concrete);  color: var(--color-graphite); }
.is-dark .hairline  { border-color: var(--hairline-on-dark); }
.is-light .hairline { border-color: var(--hairline-on-light); }

/* --- Type primitives --- */
.mega {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: var(--fs-mega);
  line-height: var(--lh-mega);
  letter-spacing: var(--tracking-mega);
  text-transform: uppercase;
  text-wrap: balance;
}
.display {
  font-weight: 700;
  font-size: var(--fs-display);
  line-height: var(--lh-tight);
  letter-spacing: var(--tracking-display);
  text-transform: uppercase;
  text-wrap: balance;
}
.label {
  font-size: var(--fs-label);
  font-weight: 500;
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
}
.mono {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: 0.02em;
}
.body-copy { max-width: 62ch; }
.body-copy + .body-copy { margin-top: 1.1em; }

/* --- Hairline rule --- */
.hairline { border: 0; border-top: 1px solid var(--hairline-on-dark); }

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 20px 44px;
  border-radius: var(--radius-none);
  border: 1px solid var(--color-chalk);
  background: var(--color-chalk);
  color: var(--color-void);
  font-size: var(--fs-label);
  font-weight: 600;
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  transition: background var(--dur-state) var(--ease-out-expo),
              color var(--dur-state) var(--ease-out-expo);
}
.btn:hover { background: var(--color-void); color: var(--color-chalk); }
.btn svg { width: 16px; height: 16px; }

/* --- Circular Explore control: the one curve in the system --- */
.explore {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 124px;
  height: 124px;
  border: 1px solid currentColor;
  border-radius: var(--radius-circle);
  font-size: var(--fs-label);
  font-weight: 500;
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  transition: background var(--dur-state) var(--ease-out-expo),
              color var(--dur-state) var(--ease-out-expo);
}
.explore svg { width: 14px; height: 14px; }
.is-dark .explore:hover  { background: var(--color-chalk); color: var(--color-void); }
.is-light .explore:hover { background: var(--color-graphite); color: var(--color-concrete); }

/* --- Accessibility --- */
.skip-link {
  position: absolute;
  left: 12px;
  top: -100px;
  z-index: 1000;
  padding: 12px 18px;
  background: var(--color-chalk);
  color: var(--color-void);
  font-size: var(--fs-label);
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  transition: top var(--dur-state) var(--ease-out-expo);
}
.skip-link:focus { top: 12px; }

a:focus-visible, button:focus-visible, input:focus-visible,
select:focus-visible, textarea:focus-visible {
  outline: 2px solid currentColor;
  outline-offset: 3px;
}
.visually-hidden {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

/* Media defaults: imagery is grayscale in this system */
.media-img { width: 100%; height: 100%; object-fit: cover; filter: grayscale(1); }