/*
 * Torsor — design tokens
 * "Solarized Cézanne": warm paper, sage, terracotta, blue-grey, ochre, dusty plum.
 * Geometry + twisting + simplicity. Klee/Cézanne palette, Roboto family.
 */

:root {
  /* --- Neutrals: warm paper / parchment --- */
  --paper-0:  #faf6ee;   /* page bg, lightest */
  --paper-1:  #f3ecdd;   /* panel */
  --paper-2:  #ebe1cc;   /* hover / sunken */
  --paper-3:  #ddd0b6;   /* border subtle */
  --paper-4:  #c9b994;   /* border strong */

  --ink-0:    #2a2620;   /* text high */
  --ink-1:    #4a4136;   /* text body */
  --ink-2:    #6e6353;   /* text muted */
  --ink-3:    #8e8270;   /* text dim */

  /* --- Cézanne accents (oklch-tuned, washed) --- */
  --sage:       oklch(64% 0.07 145);   /* foliage */
  --sage-deep:  oklch(48% 0.07 150);
  --sage-soft:  oklch(85% 0.04 145);

  --terracotta:      oklch(62% 0.13 40);   /* roof, primary */
  --terracotta-deep: oklch(48% 0.14 38);
  --terracotta-soft: oklch(88% 0.05 45);

  --skyblue:      oklch(64% 0.08 235);    /* sky / link */
  --skyblue-deep: oklch(46% 0.10 235);
  --skyblue-soft: oklch(88% 0.04 235);

  --ochre:      oklch(72% 0.12 80);       /* wheat field */
  --ochre-deep: oklch(58% 0.13 75);
  --ochre-soft: oklch(90% 0.06 85);

  --plum:       oklch(50% 0.09 350);      /* dusty figure */
  --plum-deep:  oklch(38% 0.10 350);
  --plum-soft:  oklch(86% 0.04 350);

  /* Redon "pop" — used sparingly for highlights */
  --gold:       oklch(78% 0.15 85);
  --vermilion:  oklch(60% 0.18 28);

  /* --- Semantic --- */
  --bg:        var(--paper-0);
  --bg-panel:  var(--paper-1);
  --bg-sunken: var(--paper-2);
  --border:    var(--paper-3);
  --border-strong: var(--paper-4);

  --text:      var(--ink-0);
  --text-body: var(--ink-1);
  --muted:     var(--ink-2);
  --dim:       var(--ink-3);

  --accent:        var(--terracotta);
  --accent-deep:   var(--terracotta-deep);
  --accent-soft:   var(--terracotta-soft);
  --link:          var(--skyblue-deep);
  --link-hover:    var(--terracotta-deep);

  --success: var(--sage-deep);
  --warning: var(--ochre-deep);
  --danger:  var(--vermilion);

  /* --- Typography --- */
  --font-sans:    'Roboto Flex', 'Roboto', system-ui, sans-serif;
  --font-body:    'Roboto', system-ui, sans-serif;
  --font-serif:   'Roboto Serif', 'Source Serif 4', Georgia, serif;
  --font-mono:    'Roboto Mono', ui-monospace, 'JetBrains Mono', monospace;
  --font-math:    'Roboto Serif', 'Latin Modern Math', 'STIX Two Math', serif;

  /* Type scale (modular, ratio ~1.2) */
  --text-2xs: 0.6875rem;   /* 11 */
  --text-xs:  0.75rem;     /* 12 */
  --text-sm:  0.8125rem;   /* 13 */
  --text-base:0.9375rem;   /* 15 */
  --text-md:  1rem;        /* 16 */
  --text-lg:  1.1875rem;   /* 19 */
  --text-xl:  1.4375rem;   /* 23 */
  --text-2xl: 1.75rem;     /* 28 */
  --text-3xl: 2.125rem;    /* 34 */
  --text-4xl: 2.625rem;    /* 42 */
  --text-5xl: 3.375rem;    /* 54 */

  --leading-tight: 1.18;
  --leading-snug:  1.32;
  --leading-body:  1.55;
  --leading-loose: 1.75;

  /* --- Spacing (4px base) --- */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-7: 3rem;
  --space-8: 4rem;
  --space-9: 6rem;

  /* --- Radii: small. Torsor = simple, geometric, not rounded-blobby --- */
  --radius-1: 2px;
  --radius-2: 4px;
  --radius-3: 6px;
  --radius-pill: 999px;

  /* --- Shadows: soft, paper-like --- */
  --shadow-1: 0 1px 0 rgba(74, 65, 54, 0.06);
  --shadow-2: 0 1px 2px rgba(74, 65, 54, 0.08), 0 0 0 1px rgba(74, 65, 54, 0.04);
  --shadow-3: 0 4px 12px rgba(74, 65, 54, 0.10), 0 1px 2px rgba(74, 65, 54, 0.05);

  /* --- Layout --- */
  --measure: 68ch;          /* readable column */
  --measure-wide: 86ch;
  --content-max: 1180px;

  /* --- Motion --- */
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --dur-fast: 120ms;
  --dur:      200ms;
  --dur-slow: 360ms;
}

/* --- Dark "warm dusk" theme (Cézanne nightfall) --- */
[data-theme="dark"] {
  --paper-0:  #1c1a16;
  --paper-1:  #25221c;
  --paper-2:  #2f2b23;
  --paper-3:  #403a2f;
  --paper-4:  #59503f;

  --ink-0:    #ede4cf;
  --ink-1:    #d6cdb6;
  --ink-2:    #a89e84;
  --ink-3:    #7d745d;

  --sage:       oklch(70% 0.08 145);
  --sage-deep:  oklch(78% 0.08 150);
  --sage-soft:  oklch(36% 0.05 145);

  --terracotta:      oklch(70% 0.14 42);
  --terracotta-deep: oklch(78% 0.14 42);
  --terracotta-soft: oklch(34% 0.07 40);

  --skyblue:      oklch(70% 0.09 235);
  --skyblue-deep: oklch(78% 0.09 235);
  --skyblue-soft: oklch(34% 0.05 235);

  --ochre:      oklch(78% 0.12 82);
  --ochre-deep: oklch(82% 0.13 80);
  --ochre-soft: oklch(36% 0.06 80);

  --plum:       oklch(70% 0.09 350);
  --plum-deep:  oklch(78% 0.09 350);
  --plum-soft:  oklch(34% 0.06 350);

  --link:        var(--skyblue-deep);
  --link-hover:  var(--terracotta-deep);

  --shadow-1: 0 1px 0 rgba(0,0,0,0.3);
  --shadow-2: 0 1px 2px rgba(0,0,0,0.4), 0 0 0 1px rgba(255,237,200,0.04);
  --shadow-3: 0 4px 14px rgba(0,0,0,0.5), 0 1px 2px rgba(0,0,0,0.3);
}

/* --- Base resets / element styling --- */
*, *::before, *::after { box-sizing: border-box; }
html { font-size: 16px; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text-body);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  -webkit-font-smoothing: antialiased;
  font-feature-settings: "kern", "liga", "ss01";
}

/* Subtle paper texture on body */
body.paper-texture::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    radial-gradient(circle at 13% 27%, rgba(110,99,83,0.025) 0, transparent 50%),
    radial-gradient(circle at 87% 73%, rgba(110,99,83,0.02) 0, transparent 60%);
  mix-blend-mode: multiply;
}

h1, h2, h3, h4, h5 {
  font-family: var(--font-sans);
  color: var(--text);
  font-weight: 500;
  line-height: var(--leading-tight);
  letter-spacing: -0.012em;
  margin: 0 0 var(--space-3);
}
h1 { font-size: var(--text-4xl); font-weight: 400; letter-spacing: -0.02em; }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }
h5 { font-size: var(--text-md); text-transform: uppercase; letter-spacing: 0.06em; color: var(--muted); font-weight: 500; }

p { margin: 0 0 var(--space-4); max-width: var(--measure); }

a {
  color: var(--link);
  text-decoration: none;
  border-bottom: 1px solid color-mix(in oklch, var(--link), transparent 70%);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
a:hover { color: var(--link-hover); border-bottom-color: currentColor; }

code, kbd, samp {
  font-family: var(--font-mono);
  font-size: 0.92em;
  background: var(--bg-sunken);
  color: var(--text);
  padding: 0.08em 0.35em;
  border-radius: var(--radius-1);
  border: 1px solid var(--border);
}
pre {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1.55;
  background: var(--bg-panel);
  color: var(--text);
  padding: var(--space-4) var(--space-5);
  border-radius: var(--radius-2);
  border: 1px solid var(--border);
  overflow-x: auto;
  margin: 0 0 var(--space-5);
}
pre code { background: none; border: none; padding: 0; font-size: inherit; }

hr {
  border: 0;
  border-top: 1px solid var(--border);
  margin: var(--space-6) 0;
}

::selection { background: color-mix(in oklch, var(--ochre), transparent 60%); color: var(--text); }

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: 500;
  line-height: 1;
  padding: 0.55rem 0.95rem;
  border-radius: var(--radius-2);
  border: 1px solid var(--accent-deep);
  background: var(--accent);
  color: var(--paper-0);
  cursor: pointer;
  transition: filter var(--dur) var(--ease), transform var(--dur-fast) var(--ease);
}
.btn:hover { filter: brightness(0.95); }
.btn:active { transform: translateY(1px); }
.btn--ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--border-strong);
}
.btn--ghost:hover { background: var(--bg-sunken); filter: none; }
.btn--quiet {
  background: transparent;
  color: var(--muted);
  border-color: transparent;
  padding: 0.45rem 0.6rem;
}
.btn--quiet:hover { background: var(--bg-sunken); color: var(--text); filter: none; }
.btn--sm { font-size: var(--text-xs); padding: 0.35rem 0.65rem; }

/* --- Inputs --- */
.field {
  font-family: var(--font-body);
  font-size: var(--text-base);
  background: var(--bg);
  color: var(--text);
  padding: 0.5rem 0.7rem;
  border-radius: var(--radius-2);
  border: 1px solid var(--border-strong);
  outline: none;
  transition: border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}
.field:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in oklch, var(--accent), transparent 80%);
}
select.field { padding-right: 2rem; appearance: none;
  background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%), linear-gradient(135deg, var(--muted) 50%, transparent 50%);
  background-position: calc(100% - 18px) 50%, calc(100% - 13px) 50%;
  background-size: 5px 5px, 5px 5px; background-repeat: no-repeat; }

/* --- Card --- */
.card {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-3);
  padding: var(--space-5);
  box-shadow: var(--shadow-1);
}

/* --- Badges --- */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.3em;
  font-family: var(--font-sans);
  font-size: var(--text-2xs);
  font-weight: 500;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 0.18rem 0.5rem;
  border-radius: var(--radius-pill);
  border: 1px solid currentColor;
  color: var(--accent-deep);
  background: color-mix(in oklch, var(--accent), transparent 88%);
}
.badge--sage   { color: var(--sage-deep);       background: color-mix(in oklch, var(--sage),       transparent 88%); }
.badge--sky    { color: var(--skyblue-deep);    background: color-mix(in oklch, var(--skyblue),    transparent 88%); }
.badge--ochre  { color: var(--ochre-deep);      background: color-mix(in oklch, var(--ochre),      transparent 85%); }
.badge--plum   { color: var(--plum-deep);       background: color-mix(in oklch, var(--plum),       transparent 85%); }

/* --- Tables --- */
table.t {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius-3);
  overflow: hidden;
}
table.t th, table.t td {
  text-align: left;
  padding: 0.55rem 0.8rem;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}
table.t th {
  background: var(--bg-sunken);
  font-weight: 500;
  color: var(--muted);
  text-transform: uppercase;
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
}
table.t tr:last-child td { border-bottom: none; }
table.t tr:hover td { background: color-mix(in oklch, var(--ochre-soft), transparent 60%); }

/* --- Math display (KaTeX-ish) --- */
.eq {
  font-family: var(--font-math);
  font-style: italic;
  font-size: 1.02em;
}
.eq--display {
  display: block;
  text-align: center;
  margin: var(--space-5) 0;
  font-size: 1.08em;
}
.eq sub, .eq sup { font-style: normal; font-size: 0.7em; }

/* --- Citations / footnotes --- */
.cite {
  font-variant-numeric: oldstyle-nums;
  color: var(--accent-deep);
  font-size: 0.78em;
  vertical-align: super;
  text-decoration: none;
  border: none;
  margin-left: 1px;
  padding: 0 0.2em;
}
.cite:hover { background: color-mix(in oklch, var(--accent), transparent 85%); border-radius: 2px; }

.references {
  font-size: var(--text-sm);
  color: var(--text-body);
  counter-reset: ref;
  list-style: none;
  padding-left: 0;
}
.references li {
  counter-increment: ref;
  padding-left: 2.4em;
  position: relative;
  margin-bottom: var(--space-3);
  line-height: var(--leading-snug);
}
.references li::before {
  content: "[" counter(ref) "]";
  position: absolute;
  left: 0;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
  font-family: var(--font-mono);
  font-size: 0.85em;
  top: 0.1em;
}
.references cite { font-style: italic; color: var(--text); }

/* --- Section eyebrow / kicker --- */
.kicker {
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--accent-deep);
  margin-bottom: var(--space-3);
}

/* --- Decorative geometric mark (the "torsor mark") --- */
.torsor-mark {
  display: inline-block;
  width: 1em; height: 1em;
  vertical-align: -0.15em;
}

/* --- Utility --- */
.muted { color: var(--muted); }
.dim   { color: var(--dim); }
.mono  { font-family: var(--font-mono); }
.serif { font-family: var(--font-serif); }
.center{ text-align: center; }
.stack > * + * { margin-top: var(--space-4); }
.row { display: flex; gap: var(--space-4); align-items: center; flex-wrap: wrap; }
.grow { flex: 1 1 auto; }

/* --- Container --- */
.container {
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 var(--space-5);
  position: relative;
  z-index: 1;
}
.prose { max-width: var(--measure); }
.prose p { max-width: none; }