/* ═══════════════════════════════════════════════════════════════════════════
   Paper design system
   The Enterprise AI Operating System — sunilprakash.com/enterprise-ai
   Paper + ink on the page; obsidian + gold only inside board panels.
   ═══════════════════════════════════════════════════════════════════════════ */

:root {
  --paper: #f5f1e8;
  --surface: #fbf9f4;
  --ledger: #ece6d8;
  --rule: #d9d2c3;
  --ink: #16130e;
  --ink-2: #4a443a;
  --ink-3: #6a6357;
  --bronze: #7a5c1e;
  --board: #0b0a08;
  --board-ink: #f0ece4;
  --gold: #c8b48c;
  --measure: 680px;
  --wide: 960px;
  --rail: 240px;
  --font-display: 'Fraunces', Georgia, 'Times New Roman', serif;
  --font-body: 'IBM Plex Sans', system-ui, -apple-system, sans-serif;
  --font-mono: 'IBM Plex Mono', ui-monospace, Menlo, monospace;
  --ease: cubic-bezier(.2, .6, .2, 1);
}

/* ─── Fonts (self-hosted) ─────────────────────────────────────────────────── */
@font-face { font-family: 'Fraunces'; src: url('../fonts/Fraunces-Variable.woff2') format('woff2'); font-weight: 100 900; font-style: normal; font-display: swap; }
@font-face { font-family: 'Fraunces'; src: url('../fonts/Fraunces-Italic-Variable.woff2') format('woff2'); font-weight: 100 900; font-style: italic; font-display: swap; }
@font-face { font-family: 'IBM Plex Sans'; src: url('../fonts/IBMPlexSans-Light.woff2') format('woff2'); font-weight: 300; font-display: swap; }
@font-face { font-family: 'IBM Plex Sans'; src: url('../fonts/IBMPlexSans-Regular.woff2') format('woff2'); font-weight: 400; font-display: swap; }
@font-face { font-family: 'IBM Plex Sans'; src: url('../fonts/IBMPlexSans-Medium.woff2') format('woff2'); font-weight: 500; font-display: swap; }
@font-face { font-family: 'IBM Plex Sans'; src: url('../fonts/IBMPlexSans-SemiBold.woff2') format('woff2'); font-weight: 600; font-display: swap; }
@font-face { font-family: 'IBM Plex Mono'; src: url('../fonts/IBMPlexMono-Regular.woff2') format('woff2'); font-weight: 400; font-display: swap; }
@font-face { font-family: 'IBM Plex Mono'; src: url('../fonts/IBMPlexMono-Medium.woff2') format('woff2'); font-weight: 500; font-display: swap; }

/* ─── Base ────────────────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 400 18px/1.6 var(--font-body); -webkit-font-smoothing: antialiased; }
a { color: var(--bronze); text-decoration-color: rgba(122, 92, 30, .35); text-underline-offset: .15em; }
a:hover { text-decoration-color: var(--bronze); }
img, svg { max-width: 100%; height: auto; }
h1, h2, h3, h4 { font-family: var(--font-display); font-weight: 300; color: var(--ink); line-height: 1.15; margin: 0 0 .5em; letter-spacing: -.01em; }
h1 { font-size: 44px; }
h2 { font-size: 30px; margin-top: 2.2em; }
h3 { font-size: 22px; font-weight: 400; margin-top: 1.8em; }
h4 { font-size: 18px; font-family: var(--font-body); font-weight: 600; margin-top: 1.6em; }
p, ul, ol { margin: 0 0 1.2em; }
li { margin: .3em 0; }
strong { font-weight: 600; }
.label { font: 500 11px/1.4 var(--font-mono); letter-spacing: .14em; text-transform: uppercase; color: var(--bronze); }
.meta { font: 400 13px/1.5 var(--font-mono); color: var(--ink-3); }
.dek { font-size: 21px; line-height: 1.45; color: var(--ink-2); font-weight: 300; max-width: var(--measure); }
.skip-link { position: absolute; left: -999px; top: 8px; background: var(--ink); color: var(--paper); padding: 8px 12px; z-index: 100; }
.skip-link:focus { left: 8px; }
:focus-visible { outline: 2px solid var(--bronze); outline-offset: 2px; }

/* ─── Layout ──────────────────────────────────────────────────────────────── */
.page { max-width: 1200px; margin: 0 auto; padding: 0 28px; }
.reading { display: grid; grid-template-columns: minmax(0, var(--measure)) var(--rail); gap: 64px; justify-content: center; padding: 48px 28px 96px; }
.reading > article { min-width: 0; }
.page-header { margin-bottom: 8px; }
.page-header h1 { margin-bottom: 14px; }
.rail { position: sticky; top: 88px; align-self: start; font-size: 14px; }
.rail .label { display: block; margin-bottom: 10px; }
.rail ol { list-style: none; padding: 0; margin: 0; border-left: 1px solid var(--rule); }
.rail li { margin: 0; }
.rail li a { display: block; padding: 6px 0 6px 14px; color: var(--ink-2); text-decoration: none; border-left: 2px solid transparent; margin-left: -1px; line-height: 1.35; }
.rail li.current a { color: var(--ink); border-left-color: var(--bronze); }
.rail li a:hover { color: var(--ink); }
.content-wide { max-width: var(--wide); margin-left: auto; margin-right: auto; }

/* ─── Top bar ─────────────────────────────────────────────────────────────── */
.topbar { position: sticky; top: 0; z-index: 50; background: rgba(245, 241, 232, .94); backdrop-filter: saturate(140%) blur(8px); -webkit-backdrop-filter: saturate(140%) blur(8px); border-bottom: 1px solid var(--rule); }
.topbar .inner { max-width: 1200px; margin: 0 auto; padding: 0 28px; height: 60px; display: flex; align-items: center; gap: 28px; }
.wordmark { font-family: var(--font-display); font-weight: 500; font-size: 19px; color: var(--ink); text-decoration: none; display: flex; align-items: center; gap: 10px; white-space: nowrap; }
.wordmark img { width: 22px; height: 22px; }
.topnav { display: flex; gap: 22px; margin-left: auto; align-items: center; }
.topnav a, .topnav button { font: 500 14px/1 var(--font-body); color: var(--ink-2); text-decoration: none; background: none; border: 0; padding: 8px 0; cursor: pointer; }
.topnav a:hover, .topnav button:hover { color: var(--ink); }
.topnav .has-menu { position: relative; }
.menu { position: absolute; top: 100%; left: -16px; min-width: 400px; background: var(--surface); border: 1px solid var(--rule); box-shadow: 0 12px 32px rgba(22, 19, 14, .08); padding: 10px 0; display: none; }
.has-menu.open .menu { display: block; }
.menu a { display: grid; grid-template-columns: 32px 1fr; gap: 10px; padding: 9px 18px; text-decoration: none; color: var(--ink); font-size: 15px; }
.menu a:hover { background: var(--ledger); }
.menu .n { font: 500 12px/1.6 var(--font-mono); color: var(--bronze); }
.menu .q { display: block; font-size: 13px; color: var(--ink-3); margin-top: 2px; line-height: 1.35; }
.search-btn { display: flex; align-items: center; gap: 8px; border: 1px solid var(--rule) !important; padding: 6px 10px !important; border-radius: 4px; color: var(--ink-3) !important; }
.search-btn kbd { font: 400 11px var(--font-mono); color: var(--ink-3); }
.menu-toggle { display: none; }
.breadcrumb { font: 400 13px/1.4 var(--font-mono); color: var(--ink-3); margin: 0 0 18px; }
.breadcrumb a { color: var(--bronze); text-decoration: none; }
.breadcrumb .sep { margin: 0 8px; color: var(--rule); }

/* ─── Progress bar ────────────────────────────────────────────────────────── */
.progress { position: fixed; top: 0; left: 0; height: 2px; width: 0; background: var(--bronze); z-index: 60; transition: width .1s linear; }

/* ─── Footer ──────────────────────────────────────────────────────────────── */
.site-footer { border-top: 1px solid var(--rule); margin-top: 96px; padding: 48px 28px 40px; background: var(--ledger); }
.site-footer .cols { max-width: 1200px; margin: 0 auto; display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 32px; font-size: 14px; }
.site-footer h4 { margin: 0 0 10px; font: 500 11px/1.4 var(--font-mono); letter-spacing: .14em; text-transform: uppercase; color: var(--bronze); }
.site-footer ul { list-style: none; padding: 0; margin: 0; }
.site-footer li { margin: 4px 0; }
.site-footer a { color: var(--ink-2); text-decoration: none; }
.site-footer a:hover { color: var(--ink); }
.site-footer .blurb { margin: 0 0 10px; color: var(--ink-2); }
.site-footer .fine { max-width: 1200px; margin: 32px auto 0; font: 400 12px/1.6 var(--font-mono); color: var(--ink-3); display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; }

/* ─── Command palette ─────────────────────────────────────────────────────── */
.palette { position: fixed; inset: 0; background: rgba(22, 19, 14, .35); display: none; z-index: 90; align-items: flex-start; justify-content: center; padding-top: 12vh; }
.palette[aria-hidden="false"] { display: flex; }
.palette .box { width: min(640px, 92vw); background: var(--surface); border: 1px solid var(--rule); box-shadow: 0 24px 60px rgba(22, 19, 14, .2); }
.palette input { width: 100%; border: 0; border-bottom: 1px solid var(--rule); padding: 16px 18px; font: 400 17px var(--font-body); background: transparent; color: var(--ink); outline: none; }
.palette ol { list-style: none; margin: 0; padding: 8px 0; max-height: 50vh; overflow: auto; }
.palette li { margin: 0; }
.palette li a { display: block; padding: 10px 18px; text-decoration: none; color: var(--ink); }
.palette li.sel a, .palette li a:hover { background: var(--ledger); }
.palette li .where { display: block; font: 400 12px var(--font-mono); color: var(--ink-3); margin-top: 2px; }
.palette .empty { padding: 14px 18px; color: var(--ink-3); font-size: 14px; }

/* ─── Mobile sheet ────────────────────────────────────────────────────────── */
.sheet { position: fixed; inset: 0; background: var(--paper); z-index: 80; display: none; overflow: auto; padding: 24px; }
.sheet[aria-hidden="false"] { display: block; }
.sheet .close { float: right; background: none; border: 1px solid var(--rule); padding: 6px 10px; font: 500 13px var(--font-body); color: var(--ink); }
.sheet h4 { margin: 24px 0 8px; font: 500 11px/1.4 var(--font-mono); letter-spacing: .14em; text-transform: uppercase; color: var(--bronze); }
.sheet a { display: block; padding: 9px 0; color: var(--ink); text-decoration: none; border-bottom: 1px solid var(--rule); font-size: 16px; }
.sheet a .q { display: block; font-size: 13px; color: var(--ink-3); }

/* ─── Reveal (opt-in only; never on body text) ────────────────────────────── */
.reveal { opacity: 0; transform: translateY(8px); transition: opacity .6s var(--ease), transform .6s var(--ease); }
.reveal.in { opacity: 1; transform: none; }
.no-js .reveal { opacity: 1; transform: none; }

/* ─── Responsive ──────────────────────────────────────────────────────────── */
@media (max-width: 1100px) {
  .reading { grid-template-columns: minmax(0, var(--measure)); }
  .rail { display: none; }
}
@media (max-width: 760px) {
  body { font-size: 17px; }
  h1 { font-size: 34px; }
  h2 { font-size: 26px; }
  .dek { font-size: 19px; }
  .topbar .inner { height: 56px; gap: 12px; padding: 0 20px; }
  .wordmark { font-size: 17px; }
  .topnav { display: none; }
  .menu-toggle { display: inline-flex; margin-left: auto; background: none; border: 1px solid var(--rule); padding: 6px 10px; font: 500 13px var(--font-body); color: var(--ink); cursor: pointer; }
  .site-footer .cols { grid-template-columns: 1fr 1fr; }
  .site-footer { padding: 36px 20px 32px; }
  .reading { padding: 28px 20px 72px; }
  .page { padding: 0 20px; }
}
@media (max-width: 480px) {
  .site-footer .cols { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; animation: none !important; }
  .reveal { opacity: 1; transform: none; }
}