/* =================================================================
   Brainy Neurals · Blog article template · plain HTML + CSS
   -----------------------------------------------------------------
   The layout follows the width of .bn-page through container
   queries, not media queries. That lets mobile.html show the phone
   layout inside a 390 px frame on any screen. Breakpoints, by the
   width of .bn-page:
     < 600    phone sizes
     < 900    one column, sticky index bar, form after the article
     900+     column + sticky form; "On this page" box in the column
     1180+    index rail on the left
     1432+    index | column | form packed and centred; rail card
   Tokens, base rules, .btn and .nav-mono come from the Brainy
   Neurals design system (colors_and_type.css, brainyneurals.css).
   ================================================================= */

/* ---------- Tokens ---------- */
:root {
  --ink: #0A0A0B;
  --ink-2: #1A1A1D;
  --ink-3: #2A2A2E;
  --paper: #FFFFFF;
  --paper-2: #F4F4F2;
  --paper-3: #E8E8E4;
  --bone: #FAFAF8;
  --line: rgba(10,10,11,0.14);
  --line-soft: rgba(10,10,11,0.08);
  --line-dark: rgba(244,239,230,0.14);
  --muted: rgba(10,10,11,0.58);
  --muted-dark: rgba(244,239,230,0.62);
  --blue: #0655FF;
  --blue-2: #0444CC;
  --blue-tint: #DCE5FF;
  --blue-deep: #03257A;
  --signal: #B5FF3C;
  --rust: #C2410C;
  --font-sans: "IBM Plex Sans", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, monospace;
  --font-serif: "IBM Plex Serif", "Times New Roman", serif;
  --t1: cubic-bezier(.2,.7,.2,1);
  --shadow-lift: 0 30px 60px -30px rgba(10,10,11,0.35), 0 2px 6px rgba(10,10,11,0.06);
}

/* ---------- Base (design system) ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { animation-duration: 0.001ms !important; transition-duration: 0.001ms !important; }
}
body {
  margin: 0;
  font-family: var(--font-sans);
  font-weight: 400;
  font-size: 17px;
  line-height: 1.5;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  font-feature-settings: "ss01", "cv11";
}
img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; padding: 0; }
input, select, textarea { font: inherit; color: inherit; }
::selection { background: var(--ink); color: var(--paper); }
:focus-visible { outline: 2px solid var(--blue); outline-offset: 3px; border-radius: 3px; }
summary { list-style: none; }
summary::-webkit-details-marker { display: none; }

/* ---------- Buttons (design system) ---------- */
.btn {
    display: inline-flex !important;
    align-items: center !important;
    gap: 10px !important;
    height: 48px;
    min-height: 44px;
    padding: 0 22px !important;
    border-radius: 999px;
    font-family: var(--font-sans);
    font-size: 15px !important;
    font-weight: 500;
    letter-spacing: -0.005em;
    white-space: nowrap;
    transition: transform .2s var(--t1), background .2s var(--t1), color .2s var(--t1), border-color .2s var(--t1);
}
.btn .arr { transition: transform .25s var(--t1); }
.btn:hover .arr { transform: translateX(4px); }
.btn-primary { background: var(--blue); color: #fff; }
.btn-primary:hover { background: var(--blue-2); }
.btn-primary:active { background: var(--blue-deep); }
.btn-ink { background: var(--ink); color: var(--bone); }
.btn-ink:hover { background: var(--ink-2); }
.btn-ghost { background: transparent; color: var(--ink); border: 1px solid var(--line); }
.btn-ghost:hover { border-color: var(--ink); }
.btn-ghost:active { background: var(--paper-2); }

/* ---------- Page shell and layout variables ---------- */
.bn-page { container: bnpage / inline-size; position: relative; background: var(--paper); color: var(--ink); font-family: var(--font-sans); }
/* Defaults are the one-column layout (600–899 px). The container queries at the end of this file switch them. */
.bn-shell {
  --pad-x: 32px;
  --grid-top: 56px;
  --grid-bottom: 104px;
  --cols: minmax(0, 640px);
  --gap: 0px;
  --col: min(640px, 100cqw - 64px);
  --hero-pad: 48px 32px 64px;
  --hero-indent: 0px;
  --h1-max: none;
  --bleed: max(var(--pad-x), (100cqw - 640px) / 2);
}

/* ---------- Site header ---------- */
.bn-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,0.78);
  -webkit-backdrop-filter: blur(12px) saturate(140%);
  backdrop-filter: blur(12px) saturate(140%);
  border-bottom: 1px solid var(--line-soft);
}
.bn-header__inner { max-width: 1320px; margin: 0 auto; padding: 0 var(--pad-x); height: 64px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.bn-header__logo { display: inline-flex; align-items: center; flex: none; }
.bn-header__logo img { height: 34px; width: auto; }
.bn-nav { display: none; align-items: center; gap: 8px; }
.bn-nav__link { display: inline-flex; align-items: center; gap: 6px; padding: 8px 12px; border-radius: 8px; font-size: 14.5px; color: var(--ink); transition: background .15s var(--t1); }
.bn-nav__link:hover { background: rgba(10,10,11,0.06); }
.bn-nav__caret { font-size: 10px; opacity: 0.5; }
.bn-header__actions { display: none; align-items: center; gap: 12px; }
.bn-header__compact { display: flex; align-items: center; gap: 12px; }
.bn-header__menu { width: 40px; height: 40px; border-radius: 8px; border: 1px solid var(--line); display: inline-flex; flex-direction: column; align-items: center; justify-content: center; gap: 4px; background: transparent; cursor: pointer; }
.bn-header__menu span { display: block; width: 16px; height: 1.5px; background: var(--ink); }
.nav-mono { font-family: var(--font-mono); font-size: 11.5px; color: var(--muted); display: flex; align-items: center; gap: 6px; }
.nav-mono .pulse { width: 6px; height: 6px; border-radius: 50%; background: #16A34A; box-shadow: 0 0 0 0 rgba(22,163,74,.6); animation: pulse 2s infinite; }
@keyframes pulse { 0% { box-shadow: 0 0 0 0 rgba(22,163,74,.5); } 70% { box-shadow: 0 0 0 8px rgba(22,163,74,0); } 100% { box-shadow: 0 0 0 0 rgba(22,163,74,0); } }

/* ---------- Hero band ---------- */
.bn-hero { position: relative; overflow: hidden; color: #fff; background-color: #0A48E0; }
.bn-hero__bg { position: absolute; inset: 0; pointer-events: none; background: #0A48E0 url("../assets/hero/hero-desktop.webp") center / cover no-repeat; }
.bn-hero--ink .bn-hero__bg { background-color: #0A0A0B; background-image: url("../assets/hero/hero-desktop-ink.webp"); }
/* Network art fills the band from 48 px past the hero text to the right edge (left is set per layout below). */
.bn-hero__art {
  display: none; position: absolute; top: 0; bottom: 0; right: 0; pointer-events: none;
  background: url("../assets/hero/hero-network.webp") right center / auto 100% no-repeat;
  -webkit-mask-image: linear-gradient(90deg, transparent 0, #000 120px);
  mask-image: linear-gradient(90deg, transparent 0, #000 120px);
}
.bn-hero__grid { position: relative; display: grid; grid-template-columns: 300px 640px 300px; column-gap: 64px;; justify-content: center; padding: 56px 32px 72px; }
.bn-hero__text { grid-column: 1 / -1; min-width: 0; padding-left: var(--hero-indent); }
.bn-hero__link { color: #fff; text-decoration: underline; text-decoration-color: rgba(255,255,255,0.5); text-underline-offset: 3px; border-radius: 3px; }
.bn-hero__link:hover { text-decoration-color: #fff; }
.bn-hero__link:focus-visible { outline: 2px solid #fff; outline-offset: 3px; }

.bn-breadcrumb { margin: 0 0 28px; max-width: 640px; }
.bn-breadcrumb ol { list-style: none; margin: 0; padding: 0; display: flex; align-items: baseline; gap: 8px; min-width: 0; font-size: 14px; line-height: 1.5; color: #fff; white-space: nowrap; }
.bn-breadcrumb li { flex: none; }
.bn-breadcrumb li + li { display: flex; gap: 8px; }
.bn-breadcrumb li[aria-current] { flex: 1 1 auto; min-width: 0; }
.bn-breadcrumb__sep { flex: none; opacity: 0.7; }
.bn-breadcrumb__current { min-width: 0; overflow: hidden; text-overflow: ellipsis; }

/* Used when the topic page is not live: the topic leaves the breadcrumb and sits above the H1. */
.bn-topic { display: block; margin: 0 0 16px; font-family: var(--font-mono); font-size: 12px; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; color: #fff; }
.bn-article__title { margin: 0; max-width: 800px; font-size: 48px; line-height: 1.06; font-weight: 500; letter-spacing: -0.03em; color: #fff; text-wrap: balance; }
.bn-article__summary { margin: 20px 0 0; max-width: 640px; font-size: 22px; line-height: 1.45; color: #fff; text-wrap: pretty; }

.bn-byline { margin-top: 32px; max-width: 640px; padding: 20px 0; border-top: 1px solid rgba(255,255,255,0.28); border-bottom: 1px solid rgba(255,255,255,0.28); display: flex; align-items: flex-start; gap: 16px; }
.bn-avatar { width: 56px; height: 56px; border-radius: 50%; object-fit: cover; object-position: center 20%; flex: none; background: rgba(255,255,255,0.16); }
.bn-avatar--initials { display: grid; place-items: center; font-family: var(--font-mono); font-size: 15px; font-weight: 500; letter-spacing: 0.04em; color: #fff; }
.bn-byline__text { min-width: 0; flex: 1; display: flex; flex-direction: column; gap: 3px; }
.bn-byline__by { margin: 0; font-size: 16px; line-height: 1.4; font-weight: 500; color: #fff; }
.bn-byline__role { display: block; font-size: 14.5px; line-height: 1.45; color: #fff; }
.bn-byline__meta { margin: 10px 0 0; display: flex; flex-wrap: wrap; column-gap: 10px; row-gap: 2px; font-family: var(--font-mono); font-size: 12.5px; line-height: 1.6; color: #fff; }

/* ---------- Article grid ---------- */
.bn-grid { display: grid; grid-template-columns: 300px 640px 300px; column-gap: 64px; justify-content: center; align-items: start; padding: 56px 32px 104px; }
.bn-main { grid-column: 1; grid-row: 1; min-width: 0; width: 100%; max-width: 640px; }

/* ---------- Index rail (1180 px and up) ---------- */
.bn-rail { display: none; grid-column: 1; grid-row: 1; justify-self: end; width: 280px; position: sticky; top: 80px; align-self: start; flex-direction: column; gap: 32px; max-height: calc(100vh - 96px); }
.bn-toc--rail { min-height: 0; overflow-y: auto; padding: 4px; margin: -4px; }
.bn-toc__label { margin: 0 0 14px; font-family: var(--font-mono); font-size: 11.5px; line-height: 1.4; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.bn-toc__list { list-style: none; margin: 0; padding: 0; }
.bn-toc--rail .bn-toc__list { border-left: 1px solid var(--line); }
.bn-toc--rail a { display: grid; grid-template-columns: 26px minmax(0, 1fr); gap: 4px; align-items: baseline; margin-left: -1px; padding: 7px 0 7px 15px; border-left: 2px solid transparent; font-size: 14px; line-height: 1.45; font-weight: 400; color: var(--muted); transition: color .15s var(--t1), border-color .15s var(--t1); }
.bn-toc--rail a:hover { color: var(--ink); border-left-color: var(--ink); }
.bn-toc--rail a:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; border-radius: 4px; }
/* Current section: a script sets aria-current="true" on the link (see README). */
.bn-toc--rail a[aria-current="true"] { border-left-color: var(--blue); font-weight: 500; color: var(--blue); }
.bn-toc--rail .bn-toc__num { font-family: var(--font-mono); font-size: 11.5px; letter-spacing: 0.04em; }

.bn-rail-card { display: block; flex: none; padding: 22px 20px; border: 1px solid var(--line); border-radius: 14px; background: var(--paper); }
.bn-rail-card__title { margin: 0; font-size: 17px; line-height: 1.3; font-weight: 500; letter-spacing: -0.01em; }
.bn-rail-card__text { margin: 8px 0 18px; font-size: 14px; line-height: 1.55; color: var(--muted); }
.bn-rail-card a::before{display:none}
/* ---------- Share block (in the rail, or under the index below 1180 px) ---------- */
.bn-share {
    flex: none;
    display: flex;
    flex-direction: column;
    gap: 12px !important;
}
.single-post .wp-block-group {
    margin: 0;
}
.bn-share--inline { margin: 20px 0 40px; }
.bn-share--inline:first-child { margin-top: 0; } /* no contents list */
.bn-share__label { margin: 0; font-family: var(--font-mono); font-size: 11.5px; line-height: 1.4; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.bn-share__row { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.bn-share__btn { display: inline-flex; align-items: center; justify-content: center; height: 44px; min-width: 44px; padding: 0 14px; border-radius: 999px; border: 1px solid var(--line); background: var(--paper); color: var(--ink); font-family: var(--font-sans); font-size: 14px; font-weight: 500; line-height: 1; white-space: nowrap; cursor: pointer; transition: border-color .2s var(--t1), background .2s var(--t1); }
.bn-share__btn:hover { border-color: var(--ink); }
.bn-share__btn:active { border-color: var(--ink); background: var(--paper-2); }
.bn-share__btn:focus-visible { outline: 2px solid var(--blue); outline-offset: 3px; }
.bn-share__status { font-size: 14px; font-weight: 500; color: var(--ink); }
.bn-share__pref { align-self: flex-start; font-size: 14px; line-height: 1.5; color: var(--ink); text-decoration: underline; text-decoration-color: var(--line); text-underline-offset: 3px; border-radius: 3px; }
.bn-share__pref:hover { text-decoration-color: var(--ink); }

/* ---------- Sticky index bar (below 900 px) ---------- */
.bn-toc--bar {
    position: sticky;
    top: 0;
    z-index: 40;
    margin: 0;
    background: var(--paper);
    border-bottom: 1px solid var(--line);
}
.bn-toc__toggle { display: flex; align-items: center; gap: 16px; width: 100%; min-height: 52px; margin: 0; padding: 6px var(--bleed); color: var(--ink); font-family: var(--font-sans); text-align: left; cursor: pointer; }
.bn-toc__toggle:focus-visible { outline: 2px solid var(--blue); outline-offset: -4px; }
.bn-toc__toggle-text { flex: 1; min-width: 0; display: flex; flex-direction: column; justify-content: center; gap: 2px; }
.bn-toc__toggle-label { font-size: 15px; line-height: 1.4; font-weight: 500; }
.bn-chev { flex: none; width: 9px; height: 9px; margin-top: -5px; border-right: 1.5px solid var(--ink); border-bottom: 1.5px solid var(--ink); transform: rotate(45deg); transition: transform .25s var(--t1); }
.bn-toc--bar .bn-chev { margin-right: 2px; }
details[open] > summary .bn-chev { transform: rotate(-135deg); margin-top: 5px; }
.bn-toc__panel { position: absolute; top: calc(100% + 1px); left: 0; right: 0; margin: 0; padding: 0 0 8px; background: var(--paper); border-bottom: 1px solid var(--line); max-height: calc(100vh - 134px); overflow-y: auto; overscroll-behavior: contain; box-shadow: var(--shadow-lift); }
.bn-toc__panel a { display: grid; grid-template-columns: 30px minmax(0, 1fr); gap: 6px; align-items: baseline; min-height: 44px; padding: 11px var(--bleed); border-top: 1px solid var(--line-soft); font-size: 15px; line-height: 1.45; color: var(--ink); }
.bn-toc__panel li:first-child a { border-top: 0; }
.bn-toc__panel a:hover { background: var(--bone); }
.bn-toc__panel a:focus-visible { outline: 2px solid var(--blue); outline-offset: -3px; }
.bn-toc__panel .bn-toc__num, .bn-toc--box .bn-toc__num { font-family: var(--font-mono); font-size: 12px; letter-spacing: 0.04em; color: var(--muted); }
.bn-toc__panel a[aria-current="true"] { color: var(--blue); font-weight: 500; box-shadow: inset 3px 0 0 var(--blue); }
.bn-toc__panel a[aria-current="true"] .bn-toc__num { color: inherit; }

/* ---------- "On this page" box (900–1179 px) ---------- */
.bn-toc--box { display: none; margin: 0; border: 1px solid var(--line); border-radius: 14px; background: var(--paper); }
.bn-toc__summary { display: flex; align-items: center; justify-content: space-between; gap: 16px; min-height: 52px; padding: 0 20px; cursor: pointer; font-size: 16px; font-weight: 500; border-radius: 13px; }
.bn-toc__summary:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }
.bn-toc--box .bn-toc__list { padding: 0 0 8px; }
.bn-toc--box a { display: grid; grid-template-columns: 30px minmax(0, 1fr); gap: 6px; align-items: baseline; min-height: 44px; padding: 11px 20px; border-top: 1px solid var(--line-soft); font-size: 15px; line-height: 1.45; color: var(--ink); }
.bn-toc--box a:hover { background: var(--bone); }
.bn-toc--box a:focus-visible { outline: 2px solid var(--blue); outline-offset: -3px; border-radius: 8px; }

/* ---------- Featured image and placeholder diagrams ---------- */
.bn-figure { margin: 0 0 40px; }
.bn-figure__image { position: relative; aspect-ratio: 16 / 9; border-radius: 14px; overflow: hidden; background-color: var(--paper-2); background-image: linear-gradient(rgba(10,10,11,0.05) 1px, transparent 1px), linear-gradient(90deg, rgba(10,10,11,0.05) 1px, transparent 1px); background-size: 6.25% 11.1111%; border: 1px solid var(--line-soft); }
.bn-figure figcaption { margin-top: 12px; font-size: 14px; line-height: 1.5; color: var(--muted); }
/* Wordless placeholder shapes. Replace each placeholder box with a real <img>. */
.ph { position: absolute; border-radius: 2px; }
.ph--z { background: rgba(255,255,255,0.72); border: 1px dashed rgba(10,10,11,0.32); border-radius: 6px; }
.ph--o { background: #fff; border: 1px solid rgba(10,10,11,0.5); }
.ph--p { background: var(--paper); border: 1.5px solid var(--ink); }
.ph--s { background: var(--ink); }
.ph--bar { background: rgba(10,10,11,0.16); }
.ph--hl { background: var(--ink); border-radius: 0; }

/* ---------- Key takeaways ---------- */
.bn-takeaways { background: var(--bone); border: 1px solid var(--line); border-radius: 14px; padding: 32px 36px; }
.bn-takeaways__title { margin: 0; display: flex; align-items: center; gap: 10px; font-family: var(--font-mono); font-size: 12px; line-height: 1.4; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink); }
.bn-takeaways__list { list-style: none; margin: 20px 0 0; padding: 0; display: flex; flex-direction: column; gap: 14px; font-size: 18px; line-height: 1.6; }
.bn-takeaways__list li { display: flex; gap: 14px; }
.bn-sq { flex: none; background: var(--ink); }
.bn-sq--8 { width: 8px; height: 8px; }
.bn-sq--7 { width: 7px; height: 7px; }
.bn-sq--6 { width: 6px; height: 6px; }
.bn-bullet { flex: none; width: 6px; height: 6px; margin-top: calc(0.8em - 3px); background: var(--ink); }

/* ---------- Article body ---------- */
.bn-body { margin-top: 0; font-size: 18px; line-height: 1.7; }
.bn-body > p { margin: 0 0 1.1em; }
.bn-body strong { font-weight: 600; color: var(--ink); }
.bn-body a:not([class]) { color: #0655FF; text-decoration: underline; text-underline-offset: 3px; }
.bn-body a:not([class]):hover { color: #0444CC; text-decoration-thickness: 2px; }
.bn-body h2 { font-size: 30px; line-height: 1.18; font-weight: 500; letter-spacing: -0.02em; text-wrap: balance; outline: none; scroll-margin-top: 134px; }
.bn-h2__num { display: block; margin-bottom: 12px; font-family: var(--font-mono); font-size: 12px; line-height: 1; font-weight: 500; letter-spacing: 0.06em; color: var(--muted); }
.bn-body h3 { margin: 36px 0 10px; font-size: 22px; line-height: 1.3; font-weight: 500; letter-spacing: -0.015em; }
.bn-body h3.bn-faq { margin: 28px 0 10px; padding-top: 24px; border-top: 1px solid var(--line-soft); }
.bn-body h3.bn-faq--first { margin-top: 4px; padding-top: 0; border-top: 0; }
.bn-list { list-style: none; margin: 0 0 1.1em; padding: 0; display: flex; flex-direction: column; gap: 10px; }
.bn-list li { display: flex; gap: 14px; }
.bn-list .bn-bullet { margin-top: calc(0.85em - 3px); }

/* Table */
.bn-table { margin: 28px 0 0; }
.bn-table__scroll { overflow-x: auto; border: 1px solid var(--line); border-radius: 14px; background: var(--paper); }
.bn-table__scroll:focus-visible { outline: 2px solid var(--blue); outline-offset: 3px; }
.bn-table table { width: 100%; min-width: 620px; border-collapse: collapse; font-size: 15px; line-height: 1.5; text-align: left; }
.bn-table thead tr { background: var(--paper-2); }
.bn-table thead th { padding: 12px 16px; font-family: var(--font-mono); font-size: 11.5px; font-weight: 500; letter-spacing: 0.06em; text-transform: uppercase; vertical-align: bottom; }
.bn-table thead th + th { border-left: 1px solid var(--line); }
.bn-table tbody th { padding: 13px 16px; font-weight: 500; vertical-align: top; border-top: 1px solid var(--line); }
.bn-table tbody td { padding: 13px 16px; vertical-align: top; border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.bn-table figcaption { margin-top: 10px; font-size: 14px; line-height: 1.5; color: var(--muted); }

/* CTA slot 1, soft */
.bn-cta--soft { margin: 40px 0; padding: 28px 32px; border: 1px solid var(--line); border-radius: 14px; background: var(--paper); }
.bn-cta__label { margin: 0; font-family: var(--font-mono); font-size: 11.5px; line-height: 1.4; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.bn-cta__title { margin: 10px 0 0; font-size: 22px; line-height: 1.25; font-weight: 500; letter-spacing: -0.015em; }
.bn-cta__text { margin: 8px 0 0; font-size: 16px; line-height: 1.55; color: var(--muted); }
.bn-cta__action { margin: 20px 0 0; display: flex; }

/* Callouts */
.bn-callout { margin: 28px 0; padding: 22px 26px; }
.bn-callout.is-style-bn-build { background: var(--paper-2); border-left: 3px solid var(--ink); }
.bn-callout.is-style-bn-pitfall { background: var(--paper); border-left: 3px solid var(--rust); }
.bn-callout__label { margin: 0 0 8px; font-family: var(--font-mono); font-size: 11.5px; line-height: 1.4; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink); }
.is-style-bn-build .bn-callout__label { display: flex; align-items: center; gap: 8px; }
.is-style-bn-pitfall .bn-callout__label { color: var(--rust); }
.bn-callout__text { margin: 0; font-size: 17px; line-height: 1.65; }

/* Proof card: the whole card is clickable through its one link */
.bn-proof { position: relative; margin: 32px 0; padding: 28px 32px; border-radius: 14px; background: var(--paper-2); outline-offset: 3px; transition: background .2s var(--t1); }
.bn-proof:active { background: var(--paper-3); }
.bn-proof:has(.bn-proof__link:focus-visible) { outline: 2px solid var(--blue); }
.bn-proof__label { margin: 0; display: flex; align-items: center; gap: 8px; font-family: var(--font-mono); font-size: 11.5px; line-height: 1.4; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.bn-proof__title { margin: 10px 0 0; font-size: 22px; line-height: 1.25; font-weight: 500; letter-spacing: -0.015em; }
.bn-proof__text { margin: 8px 0 0; font-size: 16px; line-height: 1.55; color: var(--muted); }
.bn-proof__more { margin: 18px 0 0; }
.bn-proof__link { display: inline-flex; align-items: center; gap: 8px; font-size: 15px; line-height: 1.4; font-weight: 500; color: var(--blue); text-decoration: underline; text-decoration-color: transparent; text-decoration-thickness: 1.5px; text-underline-offset: 4px; outline: none; }
.bn-proof__link:focus-visible { outline: none; }
.bn-proof__link:hover { text-decoration-color: currentColor; }
.bn-proof__link::after { content: ""; position: absolute; inset: 0; border-radius: 14px; }

/* CTA slot 2, service (dark) */
.bn-cta--service { position: relative; overflow: hidden; margin: 40px 0; padding: 36px 40px; border-radius: 14px; background: var(--ink); color: var(--bone); }
.bn-cta__grid { position: absolute; inset: 0; pointer-events: none; background-image: linear-gradient(rgba(255,255,255,0.045) 1px, transparent 1px), linear-gradient(90deg, rgba(255,255,255,0.045) 1px, transparent 1px); background-size: 64px 64px; -webkit-mask-image: linear-gradient(180deg, #000, transparent 75%); mask-image: linear-gradient(180deg, #000, transparent 75%); }
.bn-cta__inner { position: relative; }
.bn-cta--service .bn-cta__label { color: var(--muted-dark); }
.bn-cta--service .bn-cta__title { margin: 12px 0 0; font-size: 28px; line-height: 1.15; letter-spacing: -0.025em; color: var(--bone); text-wrap: balance; }
.bn-cta--service .bn-cta__text { margin: 14px 0 0; line-height: 1.6; color: var(--muted-dark); }
.bn-cta--service .bn-cta__action { margin: 24px 0 0; }
.bn-cta--service .btn-primary { color: var(--bone); }
.bn-cta__link { color: #7AA0FF; text-decoration: underline; text-decoration-thickness: 1px; text-underline-offset: 3px; }
.bn-cta__link:hover { color: var(--blue-tint); text-decoration-thickness: 2px; }

/* Footnotes and sources */
.bn-fnref { line-height: 0; scroll-margin-top: 134px; }
.bn-fnref__link { margin-left: 2px; padding: 0 2px; font-family: var(--font-mono); font-size: 0.68em; font-weight: 600; color: var(--blue); text-decoration: none; }
.bn-fnref__link:hover { text-decoration: underline; }
.bn-sources { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 12px; font-size: 14.5px; line-height: 1.6; }
.bn-sources li { display: grid; grid-template-columns: 28px minmax(0, 1fr); gap: 4px; outline: none; scroll-margin-top: 134px; }
.bn-sources__num { font-family: var(--font-mono); font-size: 12.5px; color: var(--muted); }
.bn-sources__text--wrap { overflow-wrap: anywhere; }
.bn-sources__url { color: var(--blue); text-decoration: underline; text-underline-offset: 3px; }
.bn-sources__url:hover { color: var(--blue-2); text-decoration-thickness: 2px; }
.bn-sources__back { margin-left: 2px; color: var(--blue); text-decoration: none; }

/* ---------- Author box ---------- */
.bn-author { margin-top: 72px; padding-top: 28px; border-top: 1px solid var(--line); }
.bn-author__heading { margin: 0 0 18px; font-family: var(--font-mono); font-size: 12px; line-height: 1.4; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.bn-author__card { display: flex; flex-wrap: wrap; align-items: flex-start; gap: 24px; padding: 28px 32px; background: var(--bone); border: 1px solid var(--line); border-radius: 14px; }
.bn-author__photo { width: 128px; height: 128px; border-radius: 8px; object-fit: cover; object-position: center 20%; flex: none; background: var(--paper-3); }
.bn-author__initials { width: 128px; height: 128px; border-radius: 8px; flex: none; display: grid; place-items: center; background: var(--paper-3); font-family: var(--font-mono); font-size: 30px; font-weight: 500; letter-spacing: 0.04em; color: var(--ink); }
.bn-author__body { flex: 1 1 300px; min-width: 0; }
.bn-author__name { margin: 0; font-size: 22px; line-height: 1.25; font-weight: 500; letter-spacing: -0.015em; }
.bn-author__name a { color: var(--ink); text-decoration: underline; text-decoration-color: var(--line); text-decoration-thickness: 1px; text-underline-offset: 4px; }
.bn-author__name a:hover { text-decoration-color: var(--ink); }
.bn-author__role { margin: 4px 0 0; font-size: 14.5px; line-height: 1.45; color: var(--muted); }
.bn-author__bio { margin: 14px 0 0; font-size: 16px; line-height: 1.6; }
.bn-author__links { margin: 14px 0 0; display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 10px; font-size: 14.5px; line-height: 1.5; }
.bn-author__links > span { color: var(--muted); }

/* Hairline text link */
.bn-link { color: var(--ink); text-decoration: underline; text-decoration-color: var(--line); text-underline-offset: 3px; }
.bn-link:hover { text-decoration-color: var(--ink); }

/* ---------- Contact form ---------- */
.bn-form { grid-column: 1; grid-row: 2; justify-self: stretch; width: auto; max-width: 100%; min-width: 0; position: static; top: 80px; align-self: start; margin-top: 64px; overflow-y: auto; }
.bn-contact { padding: 24px; background: var(--bone); border: 1px solid var(--line); border-radius: 14px; }
.bn-contact__label { margin: 0; display: flex; align-items: center; gap: 8px; font-family: var(--font-mono); font-size: 11.5px; line-height: 1.4; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.bn-contact__title { margin: 10px 0 0; font-size: 20px; line-height: 1.25; font-weight: 500; letter-spacing: -0.015em; text-wrap: balance; }
.bn-contact__intro { margin: 8px 0 0; font-size: 14px; line-height: 1.55; color: var(--muted); }
.bn-contact__fields { margin: 20px 0 0; display: flex; flex-direction: column; gap: 14px; }
.bn-field__label { display: block; margin: 0 0 6px; font-family: var(--font-mono); font-size: 11px; line-height: 1.4; font-weight: 500; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.bn-field__input { display: block; width: 100%; height: 44px; margin: 0; padding: 0 14px; border: 1px solid var(--line); border-radius: 8px; background: #fff; color: var(--ink); font-family: var(--font-sans); font-size: 15px; line-height: 1.4; transition: border-color .2s var(--t1); }
textarea.bn-field__input { height: auto; min-height: 104px; padding: 11px 14px; line-height: 1.5; resize: vertical; }
.bn-field__input::placeholder { color: rgba(10,10,11,0.58); }
/* Errors show after the visitor leaves a field or tries to send (:user-invalid). */
.bn-field__input:user-invalid { border-color: var(--rust); }
.bn-field__input:hover, .bn-field__input:focus { border-color: var(--ink); }
.bn-field__input:focus { outline: 2px solid var(--blue); outline-offset: 2px; }
.bn-field__error { display: none; margin: 6px 0 0; font-size: 13px; line-height: 1.45; color: var(--rust); }
.bn-field__input:user-invalid + .bn-field__error { display: block; }
.bn-contact__submit { width: 100%; justify-content: center; border: 0; margin-top: 4px; }
.bn-contact__sent { margin-top: 20px; padding: 16px 18px; background: #fff; border: 1px solid var(--line); border-radius: 8px; }
.bn-contact__sent-title { margin: 0; display: flex; align-items: center; gap: 8px; font-size: 15px; line-height: 1.4; font-weight: 500; }
.bn-contact__sent-text { margin: 6px 0 0; font-size: 14px; line-height: 1.55; color: var(--muted); }
.bn-contact__sent-text span { color: var(--ink); overflow-wrap: anywhere; }
.bn-contact__again { display: inline-flex; align-items: center; min-height: 44px; margin-top: 4px; padding: 0; border: 0; background: none; font-family: var(--font-sans); font-size: 14px; font-weight: 500; color: var(--blue); cursor: pointer; text-decoration: underline; text-underline-offset: 3px; }
.bn-contact__again:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }
.bn-contact__call { margin: 18px 0 0; padding-top: 14px; border-top: 1px solid var(--line); font-size: 14px; line-height: 1.5; color: var(--muted); }
.bn-contact__legal { margin: 8px 0 0; font-size: 12.5px; line-height: 1.5; color: var(--muted); }

/* ---------- Keep reading ---------- */
.bn-related { background: var(--paper-2); padding: 80px 0; }
.bn-related__inner { max-width: 1320px; margin: 0 auto; padding: 0 var(--pad-x); }
.bn-related__title { margin: 0 0 32px; font-size: 40px; line-height: 1.05; font-weight: 500; letter-spacing: -0.03em; }
.bn-cards { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 24px; }
.bn-cards > li { display: flex; min-width: 0; }
/* One card for the blog hub and Keep reading. The title link covers the card. */
.bn-card { position: relative; flex: 1; min-width: 0; display: flex; flex-direction: column; background: var(--bone); border: 1px solid var(--line); border-radius: 14px; overflow: hidden; outline-offset: 3px; transition: transform .25s var(--t1), box-shadow .25s var(--t1), background .2s var(--t1); }
.bn-card:hover { background: #fff; transform: translateY(-2px); box-shadow: var(--shadow-lift); }
.bn-card:active { background: var(--paper-2); }
.bn-card:has(.bn-card__link:focus-visible) { outline: 2px solid var(--blue); }
@media (prefers-reduced-motion: reduce) { .bn-card:hover { transform: none; } }
.bn-card__image { position: relative; aspect-ratio: 16 / 9; background-color: var(--paper-2); background-image: linear-gradient(rgba(10,10,11,0.05) 1px, transparent 1px), linear-gradient(90deg, rgba(10,10,11,0.05) 1px, transparent 1px); background-size: 6.25% 11.1111%; border-bottom: 1px solid var(--line-soft); }
.bn-card__body { flex: 1; display: flex; flex-direction: column; gap: 10px; padding: 18px 20px 20px; }
.bn-card__topic { margin: 0; display: flex; flex-wrap: wrap; gap: 2px 8px; font-family: var(--font-mono); font-size: 11px; line-height: 1.55; font-weight: 500; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); }
.bn-card__topic a, .bn-card__meta a { position: relative; z-index: 1; color: var(--ink); text-decoration: underline; text-decoration-color: var(--line); text-underline-offset: 3px; }
.bn-card__topic a:hover, .bn-card__meta a:hover { text-decoration-color: var(--ink); }
.bn-card__title { margin: 0; font-size: 19px; line-height: 1.3; font-weight: 500; letter-spacing: -0.01em; text-wrap: pretty; }
.bn-card__link { color: var(--ink); text-decoration: underline; text-decoration-color: transparent; text-decoration-thickness: 1.5px; text-underline-offset: 4px; outline: none; }
.bn-card__link:focus-visible { outline: none; }
.bn-card__link:hover { text-decoration-color: currentColor; }
.bn-card__link::after { content: ""; position: absolute; inset: 0; z-index: 0; }
.bn-card__summary { margin: 0; font-size: 14.5px; line-height: 1.55; color: var(--muted); }
.bn-card__meta { margin: auto 0 0; padding-top: 14px; border-top: 1px solid var(--line); display: flex; flex-wrap: wrap; gap: 2px 8px; font-family: var(--font-mono); font-size: 11.5px; line-height: 1.6; color: var(--muted); }

/* ---------- mobile.html frame ---------- */
.bn-mobile-body { background: var(--paper-2); }
.bn-mobile { min-height: 100vh; background: var(--paper-2); }
.bn-mobile__frame { width: 390px; max-width: 100%; margin: 0 auto; background: #fff; box-shadow: var(--shadow-lift); }

/* =================================================================
   Layouts, by the width of .bn-page
   ================================================================= */
@media (min-width: 981px) {
  .bn-nav, .bn-header__actions { display: flex; }
  .bn-header__compact { display: none; }
}

@media (min-width: 900px) {
  .bn-shell { --hero-pad: 56px 32px 72px; }
  .bn-toc--bar { display: none; }
  .bn-body h2, .bn-sources li, .bn-fnref { scroll-margin-top: 88px; }
  .bn-form { grid-column: 2; grid-row: 1; width: 280px; position: sticky; margin-top: 0; max-height: calc(100vh - 96px); }
  .bn-hero__art { display: block; }
}

/* Column + form */
@media (min-width: 900px) and (max-width: 1179px) {
  .bn-shell {
    --cols: minmax(0, 640px) 280px;
    --gap: 48px;
    --col: min(640px, calc(100vw - 392px));
    --h1-max: min(640px, calc(100vw - 392px));
  }

  .bn-toc--box { display: block; }

  .bn-hero__art {
    left: calc(max(32px, 50vw - 484px) + min(640px, calc(100vw - 392px)) + 48px);
  }
}

@media (min-width: 1180px) {
  .bn-rail { display: flex; }
  .bn-main { grid-column: 2; }
  .bn-form { grid-column: 3; }
  .bn-share--inline { display: none; }
}

/* Index | column | form, tighter */
@media (min-width: 1180px) and (max-width: 1431px) {
  .bn-shell {
    --cols: 240px minmax(0, 640px) 280px;
    --gap: 48px;
    --col: min(640px, calc(100vw - 680px));
    --h1-max: min(800px, calc(100vw - 520px));
  }

  .bn-rail { width: 240px; }

  .bn-hero__art {
    left: calc(
      max(32px, 50vw - 628px)
      + max(min(640px, calc(100vw - 680px)), var(--hero-title-w, 0px))
      + 48px
    );
  }
}

/* Index | column | form packed and centred; the column sits at the page centre */
@media (min-width: 1432px) {
  .bn-shell {
    --cols: 300px 640px 300px;
    --gap: 64px;
    --col: 640px;
    --h1-max: 800px;
    --hero-indent: 20px;
  }

  .bn-form {
    width: 300px;
    justify-self: start;
  }

  .bn-rail-card { display: block; }

  .bn-hero__art {
    left: calc(
      50vw - 616px
      + max(640px, var(--hero-title-w, 0px))
    );
  }
}

/* The rail card shows only when contents, share and card all fit in the viewport. */
@media (max-height: 925px) {
  .bn-rail .bn-rail-card { display: none; }
}

.moible{display:none}

@media (max-width:767px){
.moible{display:block}
.bn-toc__panel {
    position: absolute;
    top: calc(100% + 1px);
    left: 0;
    right: 0;
    margin: 0;
    padding: 0 0 8px;
    background: #fff;
    border-bottom: 1px solid rgba(10,10,11,0.14);
    max-height: calc(100vh - 134px);
    overflow-y: auto;
    overscroll-behavior: contain;
    box-shadow: 0 30px 60px -30px rgba(10,10,11,0.35), 0 2px 6px rgba(10,10,11,0.06);
        list-style: none;
}

.bn-toc__panel li:first-child a {
    border-top: 0;
}
.bn-toc__panel a {
    display: grid;
    grid-template-columns: 30px minmax(0, 1fr);
    gap: 6px;
    align-items: baseline;
    min-height: 44px;
    padding: 11px 20px;
    border-top: 1px solid rgba(10,10,11,0.08);
    font-size: 15px;
    line-height: 1.45;
  color: #0A0A0B !important;
        text-decoration: none !important;
}
    .bn-hero__grid {
    position: relative;
        display: grid;
        grid-template-columns: minmax(0, 1fr);
        column-gap: 0;
        justify-content: center;
        padding:28px 20px 48px;
    }
    .bn-grid {
        display: grid;
        grid-template-columns: minmax(0, 1fr);
        column-gap: var(--gap);
        justify-content: center;
        align-items: start;
        padding: 0 20px 72px;
        margin: 0;
    }
.bn-rail {
    display: none;
    grid-column: 1;
    grid-row: 1;
    justify-self: end;
    width: 280px;
    position: sticky;
    top: 80px;
    align-self: start;
    flex-direction: column;
    gap: 32px;
    max-height: calc(100vh - 96px);
}
}


/* Phone */
@media (max-width: 599px) {
  .bn-shell {
    --pad-x: 20px;
    --grid-top: 28px;
    --grid-bottom: 72px;
    --cols: minmax(0, 1fr);
    --col: calc(100vw - 40px);
    --hero-pad: 28px 20px 48px;
  }

  .bn-header__compact .btn { display: none; }

  .bn-hero__bg {
    background-image: url("../assets/hero/hero-mobile.webp");
  }

  .bn-hero--ink .bn-hero__bg {
    background-image: url("../assets/hero/hero-mobile-ink.webp");
  }

  .bn-article__title {
    font-size: 34px;
    line-height: 1.12;
  }

  .bn-article__summary { font-size: 19px; }

  .bn-takeaways { padding: 24px 22px; }

  .bn-takeaways__list,
  .bn-body {
    font-size: 17px;
  }

  .bn-body h2 {
    margin-top: 48px;
    font-size: 25px;
  }

  .bn-body h3 { font-size: 20px; }

  .bn-cta--soft,
  .bn-proof,
  .bn-author__card {
    padding: 24px 22px;
  }

  .bn-callout { padding: 18px 20px; }

  .bn-cta--service { padding: 28px 24px; }

  .bn-cta--service .bn-cta__title {
    font-size: 24px;
  }

  .bn-form { margin-top: 48px; }

  .bn-related { padding: 56px 0; }

  .bn-related__title { font-size: 30px; }
}


/* ============================================================
   §13 FAQ
   ============================================================ */
.faq-wrap { display: grid; grid-template-columns: 1fr 1.4fr; gap: 56px; align-items: start; }
.faq-list { border-top: 1px solid var(--line); }
.faq-item { border-bottom: 1px solid var(--line); }
.faq-q {
  width: 100%;
  display: grid;
  grid-template-columns: 40px 1fr 32px;
  gap: 16px;
  align-items: start;
  padding: 22px 0;
  text-align: left;
  font: inherit; color: inherit;
  cursor: pointer;
}
.faq-q .qi { font-family: "IBM Plex Mono", monospace; font-size: 12px; color: var(--muted); padding-top: 4px; }
.faq-q .qt { font-size: 18px; font-weight: 500; letter-spacing: -0.012em; line-height: 1.35; padding-top: 0; }
.faq-q .ic {
  width: 28px; height: 28px; border-radius: 50%; border: 1px solid var(--line);
  display: grid; place-items: center;
  transition: transform .3s var(--t1), background .2s var(--t1);
  align-self: start;
}
.faq-q .ic::before {
  content: ""; width: 10px; height: 1.5px; background: var(--ink); position: absolute;
}
.faq-q .ic { position: relative; }
.faq-q .ic::before, .faq-q .ic::after {
  content: ""; position: absolute; background: var(--ink); transition: transform .3s var(--t1);
}
.faq-q .ic::before { width: 10px; height: 1.5px; }
.faq-q .ic::after { width: 1.5px; height: 10px; }
.faq-item[aria-expanded="true"] .faq-q .ic { background: var(--ink); }
.faq-item[aria-expanded="true"] .faq-q .ic::before, .faq-item[aria-expanded="true"] .faq-q .ic::after { background: var(--bone); }
.faq-item[aria-expanded="true"] .faq-q .ic::after { transform: scaleY(0); }
.faq-a {
  display: grid; grid-template-rows: 0fr;
  transition: grid-template-rows .35s var(--t1);
}
.faq-a > div { overflow: hidden; }
.faq-item[aria-expanded="true"] .faq-a { grid-template-rows: 1fr; }
.faq-a .inner { padding: 0 0 28px 56px; font-size: 15.5px; line-height: 1.6; color: var(--muted); max-width: 760px; }

@media (max-width: 900px) {
  .faq-wrap { grid-template-columns: 1fr; }
  .faq-a .inner { padding-left: 56px; }
}