/* ============================================================
   ACM UEMJ — base.css
   Design tokens, reset, font loading, ambient background layers.
   "The Yantra Line" — Jantar Mantar instrument geometry fused
   with circuit-trace vocabulary, on a near-black ground.
   ============================================================ */

:root {
  /* ---- Color: locked palette ---- */
  --void: #0B0D12;
  --dune: #171B24;
  --sandstone: #C67C4E;
  --marigold: #E9AC4F;
  --cyan: #45E0CE;
  --indigo: #5A5FE0;
  --maroon: #6B2737;
  --bone: #F4EDE2;
  --slate: #8A8F9C;

  /* rgb triplets for rgba() composition */
  --cyan-rgb: 69, 224, 206;
  --indigo-rgb: 90, 95, 224;
  --sandstone-rgb: 198, 124, 78;
  --marigold-rgb: 233, 172, 79;
  --maroon-rgb: 107, 39, 55;
  --bone-rgb: 244, 237, 226;
  --void-rgb: 11, 13, 18;

  /* derived surfaces / borders — compose from these, never hand-roll rgba() elsewhere */
  --surface-glass: rgba(23, 27, 36, .62);
  --surface-glass-strong: rgba(23, 27, 36, .82);
  --border-hairline: rgba(var(--bone-rgb), .08);
  --border-hairline-strong: rgba(var(--bone-rgb), .16);
  --border-engraved-top: rgba(255, 255, 255, .06);
  --border-engraved-bottom: rgba(0, 0, 0, .5);

  /* gradients */
  --grad-brand: linear-gradient(135deg, var(--cyan), var(--indigo));
  --grad-warm: linear-gradient(135deg, var(--sandstone), var(--marigold));
  --grad-bg-glow:
    radial-gradient(60% 50% at 15% 0%, rgba(var(--cyan-rgb), .14), transparent 60%),
    radial-gradient(50% 45% at 90% 15%, rgba(var(--indigo-rgb), .12), transparent 60%),
    radial-gradient(60% 40% at 50% 100%, rgba(var(--sandstone-rgb), .08), transparent 65%);

  /* ---- Type families ---- */
  --font-display: 'Clash Display', 'IBM Plex Sans', sans-serif;
  --font-body: 'IBM Plex Sans', system-ui, -apple-system, sans-serif;
  --font-mono: 'IBM Plex Mono', ui-monospace, 'SFMono-Regular', Menlo, monospace;

  /* ---- Fluid type scale ---- */
  --fs-hero: clamp(3rem, 8vw, 7.5rem);
  --fs-h1: clamp(2.5rem, 5.2vw, 4.5rem);
  --fs-h2: clamp(2rem, 4vw, 3.25rem);
  --fs-h3: clamp(1.4rem, 2.4vw, 1.9rem);
  --fs-h4: clamp(1.1rem, 1.5vw, 1.3rem);
  --fs-body-lg: clamp(1.05rem, 1.2vw, 1.2rem);
  --fs-body: 1rem;
  --fs-small: .875rem;
  --fs-caption: .8125rem;
  --fs-mono-label: .75rem;
  --fs-mono-stat: clamp(2.5rem, 5vw, 4.25rem);

  --lh-tight: 1.05;
  --lh-snug: 1.2;
  --lh-normal: 1.5;
  --lh-relaxed: 1.7;
  --ls-tight: -0.02em;
  --ls-wide: .06em;
  --ls-widest: .18em;

  /* ---- Spacing (4px base) ---- */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --space-7: 48px;
  --space-8: 64px;
  --space-9: 96px;
  --space-10: 128px;
  --section-pad-y: clamp(80px, 10vw, 160px);
  --section-pad-y-tight: clamp(56px, 7vw, 96px);
  --container-max: 1320px;
  --container-pad: clamp(20px, 5vw, 56px);

  /* ---- Radii — restrained, engraved-stone / instrument feel ---- */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-pill: 999px;

  /* ---- Shadows ---- */
  --shadow-card: 0 24px 64px -28px rgba(0, 0, 0, .65);
  --shadow-card-hover: 0 32px 80px -24px rgba(var(--cyan-rgb), .22);
  --shadow-glow-cyan: 0 0 0 1px rgba(var(--cyan-rgb), .4), 0 0 32px -6px rgba(var(--cyan-rgb), .55);
  --shadow-engraved: inset 0 1px 0 var(--border-engraved-top), inset 0 -1px 0 var(--border-engraved-bottom);

  /* ---- Z-index scale ---- */
  --z-bg: -10;
  --z-base: 0;
  --z-content: 1;
  --z-nav: 100;
  --z-cursor: 200;
  --z-lightbox: 500;
  --z-loader: 9999;

  /* ---- Motion ---- */
  --ease-out: cubic-bezier(.16, .84, .32, 1);
  --ease-in-out: cubic-bezier(.65, 0, .35, 1);
  --dur-fast: 180ms;
  --dur-base: 400ms;
  --dur-slow: 800ms;
  --dur-loader: 2200ms;
}

/* Breakpoint reference only — var() is not usable inside @media, kept here as documentation.
   --bp-sm:480  --bp-md:768  --bp-lg:1024  --bp-xl:1280  --bp-xxl:1536 */

/* ============================================================
   Reset
   ============================================================ */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; }

html {
  scroll-behavior: auto; /* Lenis owns smooth scroll — native smooth-scroll would double-ease */
  -webkit-text-size-adjust: 100%;
}

body {
  min-height: 100svh;
  background: var(--void);
  color: var(--bone);
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: var(--lh-normal);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: var(--lh-tight);
  letter-spacing: var(--ls-tight);
  text-wrap: balance;
  overflow-wrap: anywhere;
}

p {
  text-wrap: pretty;
  overflow-wrap: break-word;
}

a { overflow-wrap: anywhere; }

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

/* The single, permanent accessibility anchor — never overridden elsewhere in the codebase */
:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

/* ============================================================
   Layout primitives
   ============================================================ */
.l-container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-pad);
}

.l-skip-link {
  position: fixed;
  top: -100%;
  left: var(--space-4);
  z-index: 10000;
  background: var(--cyan);
  color: var(--void);
  font-family: var(--font-mono);
  font-size: var(--fs-small);
  font-weight: 600;
  padding: var(--space-3) var(--space-5);
  border-radius: var(--radius-sm);
  transition: top var(--dur-fast) var(--ease-out);
}
.l-skip-link:focus {
  top: var(--space-4);
}

/* ---- Ambient background: gradient glow + noise, real DOM nodes, painted once ---- */
.l-bg-glow {
  position: fixed;
  inset: 0;
  z-index: var(--z-bg);
  pointer-events: none;
  background: var(--grad-bg-glow);
}

.l-noise {
  position: fixed;
  inset: 0;
  z-index: var(--z-bg);
  pointer-events: none;
  opacity: .025;
  mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* ---- Shared type utilities ---- */
.c-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--fs-mono-label);
  font-weight: 500;
  letter-spacing: var(--ls-widest);
  text-transform: uppercase;
  color: var(--cyan);
}
.c-eyebrow::before {
  content: '';
  width: 14px;
  height: 1px;
  background: currentColor;
}

.c-mono-stat {
  font-family: var(--font-mono);
  font-size: var(--fs-mono-stat);
  font-weight: 500;
  letter-spacing: var(--ls-tight);
  color: var(--bone);
  font-variant-numeric: tabular-nums;
}

.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;
}