/* ========================================================================
   Delta Integral -- Site Brand Tokens
   Editorial-institutional direction -- paper palette -- self-hosted fonts

   Source of truth: this file. Edit values here; downstream surfaces read from
   the :root tokens below or from /brand.css at runtime.
   Design intent + use rules: brand_system/brand_kit/BRAND.md (pointer doc).
   Site chrome additions appended after the canonical block.
   ======================================================================== */

/* ===== Brand fonts (self-hosted variable TTFs) ===== */
@font-face {
  font-family: "Source Serif 4";
  src: url("fonts/SourceSerif4-VariableFont_opsz_wght.ttf") format("truetype-variations"),
       url("fonts/SourceSerif4-VariableFont_opsz_wght.ttf") format("truetype");
  font-weight: 200 900;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "Source Serif 4";
  src: url("fonts/SourceSerif4-Italic-VariableFont_opsz_wght.ttf") format("truetype-variations"),
       url("fonts/SourceSerif4-Italic-VariableFont_opsz_wght.ttf") format("truetype");
  font-weight: 200 900;
  font-style: italic;
  font-display: swap;
}
@font-face {
  font-family: "Inter Tight";
  src: url("fonts/InterTight-VariableFont_wght.ttf") format("truetype-variations"),
       url("fonts/InterTight-VariableFont_wght.ttf") format("truetype");
  font-weight: 100 900;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "Inter Tight";
  src: url("fonts/InterTight-Italic-VariableFont_wght.ttf") format("truetype-variations"),
       url("fonts/InterTight-Italic-VariableFont_wght.ttf") format("truetype");
  font-weight: 100 900;
  font-style: italic;
  font-display: swap;
}
@font-face {
  font-family: "JetBrains Mono";
  src: url("fonts/JetBrainsMono-VariableFont_wght.ttf") format("truetype-variations"),
       url("fonts/JetBrainsMono-VariableFont_wght.ttf") format("truetype");
  font-weight: 100 900;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "JetBrains Mono";
  src: url("fonts/JetBrainsMono-Italic-VariableFont_wght.ttf") format("truetype-variations"),
       url("fonts/JetBrainsMono-Italic-VariableFont_wght.ttf") format("truetype");
  font-weight: 100 900;
  font-style: italic;
  font-display: swap;
}

:root {
  /* ============ PAPER PALETTE ============ */
  --paper:        #F4EFE6;   /* primary canvas -- warm off-white */
  --paper-2:      #ECE5D5;   /* inset panels, table stripes */
  --paper-3:      #E2DAC6;   /* deeper inset, hover surface */

  /* ============ INK ============ */
  --ink:          #1C1E22;   /* primary text, masthead */
  --ink-2:        #3E434B;   /* secondary text */
  --ink-3:        #6B6F78;   /* muted / eyebrow */
  --ink-4:        #9C9FA6;   /* faint / captions / folio */

  /* ============ RULES ============ */
  --rule:         #C9C2B2;   /* hairline */
  --rule-strong:  #9A927F;   /* emphatic rule */

  /* ============ INK ACCENTS ============ */
  --teal:         #1A5F6A;   /* Prussian teal -- interactive, verified */
  --teal-2:       #2F7A85;   /* hover / emphasis */
  --teal-dim:     rgba(26, 95, 106, 0.08);
  --ochre:        #B8822E;   /* documentary gold -- measured outcomes */
  --ochre-2:      #8F6620;
  --ochre-dim:    rgba(184, 130, 46, 0.10);
  --rouge:        #8B2E26;   /* correction, delta-down, alert */
  --rouge-dim:    rgba(139, 46, 38, 0.08);

  /* ============ TYPOGRAPHY ============ */
  --font-display: "Source Serif 4", Georgia, "Times New Roman", serif;
  --font-ui:      "Inter Tight", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-mono:    "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;

  /* Type scale */
  --fs-micro:     10.5px;   /* legal, folio */
  --fs-eyebrow:   11px;     /* section markers, uppercase labels */
  --fs-caption:   12.5px;
  --fs-body-sm:   14px;
  --fs-body:      16px;
  --fs-body-lg:   18px;     /* deck copy */
  --fs-h4:        20px;
  --fs-h3:        26px;
  --fs-h2:        36px;
  --fs-h1:        56px;
  --fs-display:   76px;     /* masthead only */

  /* Line height */
  --lh-tight:     1.04;
  --lh-snug:      1.2;
  --lh-normal:    1.5;
  --lh-relaxed:   1.65;

  /* Letter-spacing */
  --ls-display:   -0.025em;
  --ls-h:         -0.015em;
  --ls-body:       0;
  --ls-eyebrow:    0.1em;
  --ls-small-caps: 0.14em;

  /* ============ SPACING (8pt grid w/ odd helpers) ============ */
  --s-1:   4px;
  --s-2:   8px;
  --s-3:   12px;
  --s-4:   16px;
  --s-5:   20px;
  --s-6:   24px;
  --s-8:   32px;
  --s-10:  40px;
  --s-12:  48px;
  --s-16:  64px;
  --s-20:  80px;
  --s-24:  96px;

  /* ============ RADII -- conservative ============ */
  --r-0:   0;
  --r-1:   2px;        /* buttons, chips */
  --r-2:   4px;        /* tags */
  --r-3:   6px;        /* no larger -- this is an instrument, not an app */

  /* ============ ELEVATION -- hairlines instead of shadows ============ */
  --border-hair:   1px solid var(--rule);
  --border-strong: 1px solid var(--rule-strong);
  --border-ink:    1px solid var(--ink);
  --shadow-page:   0 1px 0 rgba(0,0,0,0.04);      /* only used for sticky bars */

  /* ============ MOTION ============ */
  --ease-out:      cubic-bezier(0.2, 0, 0, 1);
  --dur-fast:      120ms;
  --dur-med:       200ms;
  --dur-slow:      400ms;

  /* ============ PAGE ============ */
  --max-w:         1200px;
}

/* ========================================================================
   BASE
   ======================================================================== */

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}
body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-ui);
  font-size: var(--fs-body);
  line-height: var(--lh-normal);
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  font-feature-settings: "kern", "liga", "ss01", "cv11";
  text-rendering: optimizeLegibility;
}
a { color: inherit; text-decoration: none; }

/* ========================================================================
   SEMANTIC CLASSES -- compose these, do not re-invent
   ======================================================================== */

.di-display,
.di-h1, .di-h2, .di-h3, .di-h4 {
  font-family: var(--font-display);
  font-weight: 400;
  line-height: var(--lh-snug);
  color: var(--ink);
  text-wrap: balance;
  margin: 0;
}
.di-display { font-size: var(--fs-display); line-height: var(--lh-tight); letter-spacing: var(--ls-display); }
.di-h1      { font-size: var(--fs-h1);      line-height: var(--lh-tight); letter-spacing: var(--ls-display); }
.di-h2      { font-size: var(--fs-h2);      letter-spacing: var(--ls-h); }
.di-h3      { font-size: var(--fs-h3);      letter-spacing: var(--ls-h); font-weight: 500; }
.di-h4      { font-size: var(--fs-h4);      letter-spacing: 0; font-weight: 500; }

.di-deck {
  font-family: var(--font-ui);
  font-size: var(--fs-body-lg);
  line-height: var(--lh-relaxed);
  color: var(--ink-2);
  font-weight: 400;
}

.di-body {
  font-family: var(--font-ui);
  font-size: var(--fs-body);
  line-height: var(--lh-normal);
  color: var(--ink);
}
.di-body-sm { font-size: var(--fs-body-sm); color: var(--ink-2); line-height: var(--lh-normal); }

.di-eyebrow {
  font-family: var(--font-mono);
  font-size: var(--fs-eyebrow);
  letter-spacing: var(--ls-eyebrow);
  text-transform: uppercase;
  color: var(--ink-3);
  font-weight: 500;
}
.di-section-marker {
  font-family: var(--font-mono);
  font-size: var(--fs-eyebrow);
  letter-spacing: var(--ls-eyebrow);
  text-transform: uppercase;
  color: var(--ochre);
  font-weight: 500;
}
.di-small-caps {
  font-family: var(--font-display);
  font-variant: small-caps;
  letter-spacing: var(--ls-small-caps);
  font-weight: 400;
}

.di-mono      { font-family: var(--font-mono); font-size: var(--fs-body-sm); }
.di-numeric   { font-family: var(--font-display); font-variant-numeric: oldstyle-nums tabular-nums; letter-spacing: -0.015em; }
.di-tabular   { font-variant-numeric: tabular-nums; }

em.di-em, .di-em { font-style: italic; color: var(--teal); }

/* ========================================================================
   BUTTONS
   ======================================================================== */
.di-btn {
  display: inline-flex; align-items: center; gap: var(--s-2);
  font-family: var(--font-ui);
  font-size: var(--fs-body-sm);
  font-weight: 500;
  letter-spacing: 0;
  padding: 10px 18px;
  border-radius: var(--r-1);
  border: 1px solid transparent;
  cursor: pointer;
  transition: background var(--dur-fast) var(--ease-out), border-color var(--dur-fast) var(--ease-out), color var(--dur-fast) var(--ease-out);
}
.di-btn--primary { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.di-btn--primary:hover { background: var(--teal); border-color: var(--teal); }
.di-btn--secondary { background: transparent; color: var(--ink); border-color: var(--ink-2); }
.di-btn--secondary:hover { border-color: var(--ink); background: var(--paper-2); }
.di-btn--ghost { background: transparent; color: var(--ink-2); border-color: var(--rule); }
.di-btn--ghost:hover { color: var(--ink); border-color: var(--ink-2); }

/* ========================================================================
   HAIRLINES & CONTAINERS
   ======================================================================== */
.di-rule       { border: 0; border-top: var(--border-hair); margin: 0; }
.di-rule-strong{ border: 0; border-top: var(--border-strong); margin: 0; }
.di-frame      { border: var(--border-hair); }
.di-frame-ink  { border: var(--border-ink); }
.di-panel      { background: var(--paper-2); padding: var(--s-8); border: var(--border-hair); }

/* ========================================================================
   TAGS, CHIPS, STATUS
   ======================================================================== */
.di-tag {
  display: inline-flex; align-items: center;
  font-family: var(--font-mono);
  font-size: var(--fs-eyebrow);
  letter-spacing: var(--ls-eyebrow);
  text-transform: uppercase;
  padding: 3px 8px;
  border-radius: var(--r-1);
  color: var(--ink-2);
  background: var(--paper-3);
}
.di-tag--teal  { color: var(--teal);  background: var(--teal-dim); }
.di-tag--ochre { color: var(--ochre-2); background: var(--ochre-dim); }
.di-tag--rouge { color: var(--rouge); background: var(--rouge-dim); }

.di-status {
  display: inline-flex; align-items: center; gap: 6px;
  font-family: var(--font-mono);
  font-size: var(--fs-eyebrow);
  letter-spacing: var(--ls-eyebrow);
  text-transform: uppercase;
  color: var(--ink-3);
}
.di-status::before {
  content: ""; width: 6px; height: 6px; border-radius: 50%;
  background: var(--teal);
}
.di-status--illustrative::before { background: var(--ochre); }
.di-status--stop::before { background: var(--rouge); }

/* ========================================================================
   SITE CHROME -- nav, footer, page wrap
   Site-only. Demos do not use these classes; they live under /models/ with
   their own layout but inherit all tokens and .di-* classes above.
   ======================================================================== */

main{ flex:1; }
.page-wrap{ max-width:var(--max-w); margin:0 auto; }

/* Legacy alias -- use .di-section-marker on new code */
.section-marker{
  font-family: var(--font-mono); font-size: var(--fs-eyebrow); letter-spacing: var(--ls-eyebrow);
  text-transform: uppercase; color: var(--ink-3);
}
.section-marker.ochre{ color: var(--ochre); }

/* NAV -- folio */
.site-nav{
  border-bottom:1px solid var(--rule); background:var(--paper);
  position:sticky; top:0; z-index:50;
}
.site-nav-inner{
  max-width:var(--max-w); margin:0 auto;
  padding:14px 48px; display:flex; align-items:baseline; justify-content:space-between; gap:24px;
}
.site-mark{
  display:inline-flex; align-items:baseline; gap:14px; color:var(--ink); text-decoration:none;
}
.site-mark .glyph{
  font-family:var(--font-display); font-weight:500; font-size:26px; line-height:1; letter-spacing:-0.01em;
}
.site-mark .glyph .int{ font-style:italic; margin-left:-1px; font-weight:400; }
.site-mark .word{
  font-family:var(--font-display); font-variant:small-caps; letter-spacing:0.14em;
  font-size:13px; color:var(--ink-2); font-weight:500;
}
.site-nav-links{ display:flex; gap:28px; align-items:baseline; }
.site-nav-links a{
  font-family:var(--font-ui); font-size:14px; color:var(--ink-2);
  border-bottom:1px solid transparent; padding-bottom:2px;
  transition: color var(--dur-fast) var(--ease-out), border-color var(--dur-fast) var(--ease-out);
}
.site-nav-links a:hover{ color:var(--ink); }
.site-nav-links a.active{ color:var(--ink); border-bottom-color:var(--ink); }
.site-nav-links a.ext{ color:var(--teal); }
.site-nav-links a.ext:hover{ color:var(--teal-2); }
.site-folio{
  font-family:var(--font-mono); font-size:11px; letter-spacing:0.1em;
  text-transform:uppercase; color:var(--ink-3); white-space:nowrap;
}

/* FOOTER */
.site-footer{
  margin-top:auto;
  border-top:1px solid var(--rule-strong);
  background:var(--paper-2);
  padding:56px 48px 40px;
}
.site-footer-grid{
  max-width:var(--max-w); margin:0 auto;
  display:grid; grid-template-columns:2fr 1fr 1fr 1fr; gap:48px;
  align-items:start; margin-bottom:40px;
}
.site-footer-mark{
  font-family:var(--font-display); font-size:32px; font-weight:500; color:var(--ink); line-height:1;
}
.site-footer-mark .int{ font-style:italic; margin-left:3px; }
.site-footer-word{
  display:block; margin-top:10px;
  font-family:var(--font-display); font-variant:small-caps; letter-spacing:0.22em;
  font-size:13px; color:var(--ink-2);
}
.site-footer-blurb{
  font-family:var(--font-display); font-style:italic;
  font-size:14px; line-height:1.55; color:var(--ink-2);
  max-width:34ch; margin-top:16px;
}
.site-footer .col-head{
  font-family:var(--font-mono); font-size:10.5px; letter-spacing:0.14em;
  text-transform:uppercase; color:var(--ink-3); margin-bottom:14px;
}
.site-footer .col a{
  display:block; font-family:var(--font-ui); font-size:13.5px; color:var(--ink);
  padding:5px 0;
}
.site-footer .col a:hover{ color:var(--teal); }
.site-footer-rule{
  max-width:var(--max-w); margin:0 auto 20px;
  height:1px; background:var(--rule);
}
.site-footer-bottom{
  max-width:var(--max-w); margin:0 auto;
  display:flex; justify-content:space-between; align-items:baseline;
  font-family:var(--font-mono); font-size:10.5px; letter-spacing:0.1em;
  text-transform:uppercase; color:var(--ink-4);
}

/* ========================================================================
   RESPONSIVE -- 880px brand-canonical phone breakpoint
   ======================================================================== */
@media (max-width:880px){
  .site-nav-inner{ padding:14px 24px; flex-wrap:wrap; }
  .site-folio{ display:none; }
  .site-footer{ padding:48px 24px 32px; }
  .site-footer-grid{ grid-template-columns:1fr; gap:32px; }
  .site-footer-bottom{ flex-direction:column; gap:8px; align-items:flex-start; }
}