/* ============================================================
   base.css — Reset, design tokens, typography, layout grid
   How Physics Works — v1.0
   ============================================================ */

/* ── Design Tokens ─────────────────────────────────────────── */
:root {
  /* Background scale */
  --color-void:    oklch(0.07 0 0);
  --color-deep:    oklch(0.11 0 0);
  --color-surface: oklch(0.15 0 0);
  --color-raised:  oklch(0.19 0 0);

  /* Text */
  --color-text-primary:   oklch(0.93 0.01 90);
  --color-text-secondary: oklch(0.70 0.02 90);
  --color-text-muted:     oklch(0.55 0.02 90);

  /* Accents */
  --color-gold:   oklch(0.80 0.17 82);
  --color-plasma: oklch(0.72 0.22 310);

  /* Era accent colors */
  --era-ancient-color:     oklch(0.72 0.12 60);
  --era-revolution-color:  oklch(0.72 0.15 145);
  --era-classical-color:   oklch(0.65 0.18 240);
  --era-modern-color:      oklch(0.68 0.20 310);
  --era-contemporary-color:oklch(0.68 0.22 20);

  /* Era subtle backgrounds */
  --era-ancient-bg:      oklch(0.72 0.12 60 / 0.08);
  --era-revolution-bg:   oklch(0.72 0.15 145 / 0.08);
  --era-classical-bg:    oklch(0.65 0.18 240 / 0.08);
  --era-modern-bg:       oklch(0.68 0.20 310 / 0.08);
  --era-contemporary-bg: oklch(0.68 0.22 20 / 0.08);

  /* Typography */
  --font-display: 'Cormorant Garamond', 'Georgia', serif;
  --font-body:    'DM Sans', 'Inter', system-ui, sans-serif;
  --font-mono:    'JetBrains Mono', 'Fira Code', monospace;

  /* Type scale (fluid) */
  --text-xs:   clamp(0.70rem, 1.5vw, 0.75rem);
  --text-sm:   clamp(0.85rem, 1.8vw, 0.9rem);
  --text-base: clamp(1rem,    2vw,   1.05rem);
  --text-md:   clamp(1.1rem,  2.2vw, 1.2rem);
  --text-lg:   clamp(1.25rem, 2.5vw, 1.4rem);
  --text-xl:   clamp(1.5rem,  3vw,   1.75rem);
  --text-2xl:  clamp(1.9rem,  4vw,   2.4rem);
  --text-3xl:  clamp(2.4rem,  5vw,   3.2rem);
  --text-4xl:  clamp(3rem,    6vw,   4.5rem);

  /* Spacing */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --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;

  /* Layout */
  --content-width: 680px;
  --page-max:      1200px;
  --page-padding:  clamp(1rem, 5vw, 3rem);

  /* Radii */
  --radius-sm:  4px;
  --radius-md:  8px;
  --radius-lg:  16px;
  --radius-xl:  24px;

  /* Shadows */
  --shadow-sm:  0 1px 3px oklch(0 0 0 / 0.4);
  --shadow-md:  0 4px 16px oklch(0 0 0 / 0.5);
  --shadow-lg:  0 8px 32px oklch(0 0 0 / 0.6);
  --shadow-glow-gold:   0 0 32px oklch(0.80 0.17 82 / 0.3);
  --shadow-glow-plasma: 0 0 32px oklch(0.72 0.22 310 / 0.3);

  /* Transitions */
  --transition-fast:   0.15s ease;
  --transition-base:   0.25s ease;
  --transition-slow:   0.45s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  background-color: var(--color-void);
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

body {
  background-color: transparent;
  color: var(--color-text-primary);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.9;
  min-height: 100dvh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img, svg, canvas {
  display: block;
  max-width: 100%;
}

a {
  color: var(--color-gold);
  text-decoration: none;
  transition: color var(--transition-fast), opacity var(--transition-fast);
}
a:hover { opacity: 0.8; }
a:focus-visible {
  outline: 2px solid var(--color-gold);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

button {
  cursor: pointer;
  font-family: inherit;
  font-size: inherit;
  border: none;
  background: none;
}
button:focus-visible {
  outline: 2px solid var(--color-gold);
  outline-offset: 3px;
}

ul, ol { list-style: none; }

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  line-height: 1.2;
  font-weight: 600;
  letter-spacing: -0.01em;
}

h1 { font-size: var(--text-4xl); font-weight: 700; }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }
h5 { font-size: var(--text-lg); }
h6 { font-size: var(--text-md); }

p { max-width: 68ch; }

code, pre {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
}

/* ── Layout Utilities ───────────────────────────────────────── */
.container {
  width: 100%;
  max-width: var(--page-max);
  margin-inline: auto;
  padding-inline: var(--page-padding);
}

.content-column {
  width: 100%;
  max-width: var(--content-width);
  margin-inline: auto;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

/* ── Site Header ────────────────────────────────────────────── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: oklch(0.07 0 0 / 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid oklch(1 0 0 / 0.06);
}

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

.site-header__logo {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--color-text-primary);
  letter-spacing: -0.02em;
  white-space: nowrap;
}

.site-header__logo span {
  color: var(--color-gold);
}

.site-header__tagline {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* ── Site Footer ────────────────────────────────────────────── */
.site-footer {
  border-top: 1px solid oklch(1 0 0 / 0.06);
  padding-block: var(--space-12);
  text-align: center;
  color: var(--color-text-muted);
  font-size: var(--text-sm);
}

.site-footer a {
  color: var(--color-text-secondary);
}

/* ── Fonts ──────────────────────────────────────────────────── */
@font-face {
  font-family: 'Cormorant Garamond';
  src: url('../fonts/CormorantGaramond-Regular.woff2') format('woff2');
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'Cormorant Garamond';
  src: url('../fonts/CormorantGaramond-Italic.woff2') format('woff2');
  font-weight: 400;
  font-style: italic;
  font-display: swap;
}
@font-face {
  font-family: 'Cormorant Garamond';
  src: url('../fonts/CormorantGaramond-SemiBold.woff2') format('woff2');
  font-weight: 600;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'Cormorant Garamond';
  src: url('../fonts/CormorantGaramond-Bold.woff2') format('woff2');
  font-weight: 700;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'DM Sans';
  src: url('../fonts/DMSans-Regular.woff2') format('woff2');
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'DM Sans';
  src: url('../fonts/DMSans-Medium.woff2') format('woff2');
  font-weight: 500;
  font-style: normal;
  font-display: swap;
}