/* Proofstack AI Consulting — site styles
   Brand: navy #0B1220, teal #1FBFA6 (proofstack-brand skill).
   All colors are tokens; dark mode redefines tokens only. */

:root {
  --ink: #0B1220;          /* brand navy: header, footer, dark bands */
  --ink-2: #141E33;
  --teal: #1FBFA6;         /* brand accent: on dark surfaces, rules, marks */
  --teal-text: #0C7666;    /* teal for text/links on light surfaces (AA) */
  --teal-wash: #E3F5F1;
  --paper: #F4F6F8;
  --surface: #FFFFFF;
  --text: #172031;
  --muted: #4E5968;
  --line: #D8DFE6;
  --warn: #9A5B00;
  --warn-wash: #FFF3DF;
  --on-ink: #E8EEF3;
  --on-ink-muted: #A3AFBF;

  --f-display: "Source Serif 4", Georgia, "Times New Roman", serif;
  --f-body: "IBM Plex Sans", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --f-mono: "IBM Plex Mono", ui-monospace, Menlo, Consolas, monospace;

  --wrap: 72rem;
  --gutter: clamp(1rem, 4vw, 2.5rem);
  --radius: 6px;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0B1220;
    --surface: #111A2B;
    --text: #E6ECF1;
    --muted: #A0ACBA;
    --line: #243149;
    --teal-text: #3ED3BB;
    --teal-wash: #0F2A2C;
    --warn: #F0B45A;
    --warn-wash: #2B2112;
    --ink-2: #0E1626;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #0B1220;
  --surface: #111A2B;
  --text: #E6ECF1;
  --muted: #A0ACBA;
  --line: #243149;
  --teal-text: #3ED3BB;
  --teal-wash: #0F2A2C;
  --warn: #F0B45A;
  --warn-wash: #2B2112;
  --ink-2: #0E1626;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } *, *::before, *::after { transition: none !important; animation: none !important; } }

body {
  margin: 0;
  background: var(--paper);
  color: var(--text);
  font: 400 1.0625rem/1.65 var(--f-body);
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--teal-text); text-underline-offset: 3px; text-decoration-thickness: 1px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--teal); outline-offset: 2px; border-radius: 2px; }

.wrap { max-width: var(--wrap); margin-inline: auto; padding-inline: var(--gutter); }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 1rem; top: 1rem; z-index: 50; background: var(--surface); padding: .5rem 1rem; }

/* ---------- type scale ---------- */
h1, h2, h3 { font-family: var(--f-display); font-weight: 600; line-height: 1.15; text-wrap: balance; margin: 0; letter-spacing: -0.01em; }
h1 { font-size: clamp(2.2rem, 5vw, 3.5rem); }
h2 { font-size: clamp(1.7rem, 3.2vw, 2.35rem); }
h3 { font-size: 1.3rem; }
p { margin: 0; max-width: 65ch; }
.lede { font-size: 1.2rem; color: var(--muted); }
.label {
  font: 500 .75rem/1.3 var(--f-mono);
  letter-spacing: .12em; text-transform: uppercase; color: var(--teal-text);
}
.stack { display: grid; gap: 1rem; align-content: start; }
.stack-lg { display: grid; gap: 1.5rem; align-content: start; }

/* ---------- header (letterhead band) ---------- */
.site-header {
  position: sticky; top: env(safe-area-inset-top, 0px); z-index: 40;
  background: var(--ink); color: var(--on-ink);
  border-bottom: 3px solid var(--teal);
}
.site-header .wrap { display: flex; align-items: center; justify-content: space-between; gap: 1rem; min-height: 4.25rem; }
.brand { display: flex; align-items: center; gap: .7rem; color: inherit; text-decoration: none; }
.brand img { width: 44px; height: 36px; object-fit: cover; border-radius: 3px; }
.brand-word { display: grid; line-height: 1.05; }
.brand-word b { font: 700 1.2rem/1 Georgia, "Source Serif 4", serif; letter-spacing: .06em; }
.brand-word span { font: 600 .62rem/1.4 Arial, var(--f-body); letter-spacing: .24em; color: var(--teal); font-variant: small-caps; text-transform: uppercase; }

.nav { display: flex; align-items: center; gap: .25rem; }
.nav a { color: var(--on-ink); text-decoration: none; font-size: .95rem; padding: .5rem .7rem; border-radius: var(--radius); }
.nav a:hover { background: rgba(255,255,255,.07); }
.nav a[aria-current="page"] { color: var(--teal); }
.nav .btn { margin-left: .5rem; }
.nav-toggle { display: none; background: none; border: 1px solid rgba(255,255,255,.25); color: var(--on-ink); border-radius: var(--radius); padding: .45rem .7rem; font: 500 .85rem var(--f-body); cursor: pointer; }

@media (max-width: 960px) {
  .nav-toggle { display: inline-block; }
  .nav { display: none; position: absolute; left: 0; right: 0; top: 100%; flex-direction: column; align-items: stretch;
    background: var(--ink); border-bottom: 3px solid var(--teal); padding: .5rem var(--gutter) 1rem; }
  .nav.open { display: flex; }
  .nav a { padding: .8rem .25rem; border-bottom: 1px solid rgba(255,255,255,.08); border-radius: 0; }
  .nav .btn { margin: .75rem 0 0; text-align: center; }
}

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: .5rem;
  font: 600 .95rem/1 var(--f-body); padding: .85rem 1.25rem; border-radius: var(--radius);
  text-decoration: none; border: 1.5px solid transparent; cursor: pointer;
}
.btn-primary { background: var(--teal); color: #06221D; }
.btn-primary:hover { background: #3ACDB6; }
.btn-ghost { border-color: currentColor; color: inherit; }
.nav a.btn-primary { color: #06221D; padding: .65rem 1rem; }
.nav a.btn-primary:hover { background: #3ACDB6; }
.btn-row { display: flex; flex-wrap: wrap; gap: .75rem; align-items: center; }

/* ---------- sections ---------- */
.section { padding-block: clamp(3.5rem, 8vw, 6rem); }
.section + .section { border-top: 1px solid var(--line); }
.section-head { display: grid; gap: .8rem; margin-bottom: 2.5rem; max-width: 46rem; }
.band { background: var(--ink); color: var(--on-ink); }
.band .lede, .band p { color: var(--on-ink-muted); }
.band .label { color: var(--teal); }
.band a:not(.btn) { color: var(--teal); }

/* ---------- hero ---------- */
.hero { background: var(--ink); color: var(--on-ink); padding-block: clamp(3rem, 7vw, 5.5rem); position: relative; overflow: hidden; }
.hero::before { /* circuit-trace texture echoing the logo */
  content: ""; position: absolute; inset: 0; pointer-events: none; opacity: .5;
  background-image:
    linear-gradient(rgba(31,191,166,.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(31,191,166,.07) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: linear-gradient(100deg, transparent 35%, #000 90%);
}
.hero .wrap { position: relative; display: grid; gap: 3rem; grid-template-columns: 1.1fr .9fr; align-items: center; }
.hero h1 em { font-style: italic; color: var(--teal); }
.hero .lede { color: var(--on-ink-muted); }
.hero .label { color: var(--teal); }
.hero-simple .wrap { grid-template-columns: 1fr; }
.hero-simple .stack-lg { max-width: 48rem; }
@media (max-width: 900px) { .hero .wrap { grid-template-columns: 1fr; } }

.crumbs { font: 500 .78rem var(--f-mono); letter-spacing: .06em; color: var(--on-ink-muted); display: flex; flex-wrap: wrap; gap: .4rem; }
.crumbs a { color: var(--on-ink-muted); }

/* ---------- theory-of-operation card (signature) ---------- */
.too { margin: 0;
  background: var(--ink-2); border: 1px solid #22304A; border-radius: 10px; color: var(--on-ink);
  font-size: .92rem; box-shadow: 0 30px 60px -30px rgba(0,0,0,.6);
}
.too-head { display: flex; justify-content: space-between; gap: 1rem; padding: .9rem 1.1rem; border-bottom: 1px solid #22304A; font: 500 .72rem var(--f-mono); letter-spacing: .1em; text-transform: uppercase; color: #A3AFBF; }
.too-head b { color: var(--teal); font-weight: 500; }
.too-cols { display: grid; grid-template-columns: 1fr 1fr; }
.too-col { padding: 1rem 1.1rem 1.2rem; display: grid; gap: .55rem; align-content: start; }
.too-col + .too-col { border-left: 1px dashed #2C3B57; }
.too-col h4 { margin: 0 0 .2rem; font: 500 .7rem var(--f-mono); letter-spacing: .12em; text-transform: uppercase; color: #A3AFBF; }
.too-step { display: grid; grid-template-columns: 1.4rem 1fr; gap: .4rem; line-height: 1.35; }
.too-step i { font: normal 500 .72rem/1.6 var(--f-mono); color: #6E7C90; }
.too-step.gap { color: #F2C27B; }
.too-step.gap i { color: #F2C27B; }
.too-step.ok i { color: var(--teal); }
.too-foot { border-top: 1px solid #22304A; padding: .85rem 1.1rem; display: flex; flex-wrap: wrap; justify-content: space-between; gap: .5rem; font: 500 .75rem var(--f-mono); color: #A3AFBF; }
.too-foot b { color: var(--teal); font-weight: 500; }
@media (max-width: 480px) { .too-cols { grid-template-columns: 1fr; } .too-col + .too-col { border-left: 0; border-top: 1px dashed #2C3B57; } }

/* ---------- grids & cards ---------- */
.grid { display: grid; gap: 1.25rem; }
.g2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.g3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.g4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
@media (max-width: 960px) { .g3, .g4 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 640px) { .g2, .g3, .g4 { grid-template-columns: 1fr; } }

.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 1.5rem; display: grid; gap: .75rem; align-content: start; }
.card p { color: var(--muted); font-size: 1rem; }
/* keep labels and prices from inheriting .card p / .cta p body styles */
.card .label, .cta .label { font-size: .75rem; }
.card .label { color: var(--teal-text); }
.cta .label { color: var(--teal); }
.card .price { font-size: 2.4rem; color: var(--text); }
.card .more { font-weight: 600; font-size: .95rem; margin-top: .25rem; }
a.card { text-decoration: none; color: inherit; transition: border-color .15s, transform .15s; }
a.card:hover { border-color: var(--teal); transform: translateY(-2px); }
a.card h3 { color: var(--text); }
.card-flag { border-top: 3px solid var(--teal); }
.card.feature { padding: clamp(1.5rem, 4vw, 2.5rem); }
.card.feature p { max-width: 60ch; }

.plain { display: grid; gap: .6rem; }
.plain h3 { font-size: 1.15rem; }
.plain p { color: var(--muted); font-size: 1rem; }

/* ticks list */
.ticks { list-style: none; margin: 0; padding: 0; display: grid; gap: .6rem; }
.ticks li { position: relative; padding-left: 1.6rem; }
.ticks li::before { content: ""; position: absolute; left: .1rem; top: .55em; width: .8rem; height: .45rem; border-left: 2px solid var(--teal-text); border-bottom: 2px solid var(--teal-text); transform: rotate(-45deg); }
.band .ticks li::before { border-color: var(--teal); }
.xs { list-style: none; margin: 0; padding: 0; display: grid; gap: .6rem; }
.xs li { position: relative; padding-left: 1.6rem; color: var(--muted); }
.xs li::before { content: "—"; position: absolute; left: 0; color: var(--muted); }

/* split layout */
.split { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: clamp(2rem, 5vw, 4rem); align-items: start; }
@media (max-width: 860px) { .split { grid-template-columns: 1fr; } }

/* ---------- sequence (real processes only) ---------- */
.seq { list-style: none; margin: 0; padding: 0; counter-reset: s; display: grid; gap: 0; }
.seq > li { counter-increment: s; display: grid; grid-template-columns: 4.5rem 1fr; gap: 1.25rem; padding-block: 1.5rem; border-top: 1px solid var(--line); }
.seq > li:last-child { border-bottom: 1px solid var(--line); }
.seq > li::before { content: counter(s, decimal-leading-zero); font: 500 .85rem var(--f-mono); color: var(--teal-text); letter-spacing: .08em; padding-top: .35rem; }
.seq h3 { margin-bottom: .35rem; }
.seq p { color: var(--muted); }
.seq .when { font: 500 .75rem var(--f-mono); color: var(--muted); letter-spacing: .06em; text-transform: uppercase; display: block; margin-bottom: .3rem; }
.band .seq > li { border-color: #22304A; }
.band .seq > li::before { color: var(--teal); }
.band .seq p, .band .seq .when { color: var(--on-ink-muted); }
.band .seq h3 { color: var(--on-ink); }
@media (max-width: 560px) { .seq > li { grid-template-columns: 1fr; gap: .4rem; } }

/* seven-step method strip */
.method { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(7, minmax(0, 1fr)); border: 1px solid #22304A; border-radius: var(--radius); overflow: hidden; }
.method li { padding: 1.1rem .9rem; display: grid; gap: .35rem; align-content: start; border-left: 1px solid #22304A; }
.method li:first-child { border-left: 0; }
.method b { font: 500 .7rem var(--f-mono); color: var(--teal); letter-spacing: .1em; }
.method span { font-family: var(--f-display); font-size: 1.15rem; color: var(--on-ink); }
.method small { color: var(--on-ink-muted); font-size: .85rem; line-height: 1.4; }
@media (max-width: 960px) { .method { grid-template-columns: repeat(2, minmax(0, 1fr)); } .method li { border-left: 0; border-top: 1px solid #22304A; } .method li:nth-child(-n+2) { border-top: 0; } .method li:nth-child(even) { border-left: 1px solid #22304A; } }
@media (max-width: 480px) { .method { grid-template-columns: 1fr; } .method li:nth-child(even) { border-left: 0; } .method li:nth-child(2) { border-top: 1px solid #22304A; } }

/* five paths table */
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
table { border-collapse: collapse; width: 100%; min-width: 36rem; font-size: .98rem; }
th, td { text-align: left; padding: .9rem 1.1rem; vertical-align: top; border-bottom: 1px solid var(--line); }
th { font: 500 .72rem var(--f-mono); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); background: var(--paper); }
tr:last-child td { border-bottom: 0; }
td:first-child { font-weight: 600; white-space: nowrap; }
td { color: var(--muted); }
td:first-child { color: var(--text); }

/* notes & callouts */
.note { border: 1px solid var(--line); border-left: 3px solid var(--teal-text); background: var(--surface); padding: 1rem 1.2rem; border-radius: 0 var(--radius) var(--radius) 0; font-size: .98rem; color: var(--muted); }
.note strong { color: var(--text); }
.demo-flag { display: inline-flex; align-items: center; gap: .4rem; font: 600 .7rem var(--f-mono); letter-spacing: .1em; text-transform: uppercase; color: var(--warn); background: var(--warn-wash); border: 1px solid currentColor; padding: .3rem .55rem; border-radius: 3px; width: fit-content; }

.price { font-family: var(--f-display); font-size: 2.4rem; line-height: 1; }
.price small { font-family: var(--f-body); font-size: .95rem; color: var(--muted); }

/* case study pieces */
.flag-client { color: var(--teal); background: rgba(31,191,166,.12); }
.section:not(.band) .flag-client, .card .flag-client { color: var(--teal-text); background: var(--teal-wash); }
.quote { margin: 0; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 1.75rem; display: grid; gap: 1rem; }
.quote p { font-family: var(--f-display); font-size: 1.25rem; line-height: 1.5; color: var(--text); max-width: none; }
.quote footer { font: 500 .78rem var(--f-mono); letter-spacing: .06em; color: var(--muted); }
.quote footer span { opacity: .8; }
.record { margin: 0; display: grid; }
.record > div { display: grid; grid-template-columns: 8.5rem 1fr; gap: 1rem; padding: .75rem 1.1rem; border-top: 1px solid #22304A; }
.record > div:first-child { border-top: 0; }
.record dt { font: 500 .7rem/1.6 var(--f-mono); letter-spacing: .1em; text-transform: uppercase; color: #A3AFBF; }
.record dd { margin: 0; line-height: 1.45; }
.record .alert dd { color: #F2C27B; }
.record-light { border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
.record-light > div { border-top-color: var(--line); }
.record-light dt { color: var(--muted); }
@media (max-width: 480px) { .record > div { grid-template-columns: 1fr; gap: .2rem; } }
.sms { margin: 0; display: grid; gap: .6rem; }
.sms figcaption { font: 500 .72rem var(--f-mono); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); }
.sms p { background: var(--teal-wash); color: var(--text); border-radius: 18px 18px 18px 4px; padding: 1.1rem 1.25rem; font-size: 1rem; line-height: 1.6; max-width: 34rem; }
.method-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
@media (max-width: 960px) { .method-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 480px) { .method-4 { grid-template-columns: 1fr; } }

/* founding-cohort seat meter */
.seat-row { display: flex; flex-wrap: wrap; align-items: center; gap: .6rem; font: 500 .8rem var(--f-mono); color: var(--teal-text); border-top: 1px solid var(--line); padding-top: .85rem; }
.seats { display: inline-flex; gap: 3px; }
.seats i { width: .7rem; height: .7rem; border-radius: 2px; border: 1.5px solid var(--teal-text); }
.seats i.on { background: var(--teal-text); }

.tag { font: 500 .72rem var(--f-mono); letter-spacing: .06em; color: var(--muted); border: 1px solid var(--line); border-radius: 3px; padding: .2rem .45rem; }
.tags { display: flex; flex-wrap: wrap; gap: .4rem; }

/* resources */
.cluster { display: grid; gap: 1rem; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 1.5rem; scroll-margin-top: 6rem; }
.cluster ol { margin: 0; padding-left: 1.2rem; display: grid; gap: .45rem; color: var(--muted); }
.cluster .pillar { font-size: .92rem; border-top: 1px solid var(--line); padding-top: .9rem; color: var(--muted); }
.status { font: 500 .68rem var(--f-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }

/* FAQ */
.faq { display: grid; gap: 0; border-top: 1px solid var(--line); }
.faq details { border-bottom: 1px solid var(--line); padding-block: 1.1rem; }
.faq summary { cursor: pointer; font-weight: 600; font-size: 1.05rem; list-style: none; display: flex; justify-content: space-between; gap: 1rem; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; font: 400 1.3rem/1 var(--f-mono); color: var(--teal-text); }
.faq details[open] summary::after { content: "–"; }
.faq details p { margin-top: .75rem; color: var(--muted); }

/* CTA band */
.cta { background: var(--ink); color: var(--on-ink); padding-block: clamp(3rem, 7vw, 4.5rem); border-top: 3px solid var(--teal); }
.cta .wrap { display: grid; grid-template-columns: 1.4fr 1fr; gap: 2rem; align-items: center; }
.cta p { color: var(--on-ink-muted); }
.cta .contact-lines { display: grid; gap: .35rem; font: 500 .95rem var(--f-mono); color: var(--on-ink); }
.cta .contact-lines a { color: var(--teal); }
@media (max-width: 800px) { .cta .wrap { grid-template-columns: 1fr; } }

/* footer */
.site-footer { background: var(--ink); color: var(--on-ink-muted); border-top: 1px solid #1E2A40; padding-block: 3rem 2rem; font-size: .95rem; }
.foot-grid { display: grid; grid-template-columns: 1.4fr repeat(3, 1fr); gap: 2rem; }
.site-footer h2 { font: 500 .72rem var(--f-mono); letter-spacing: .12em; text-transform: uppercase; color: var(--on-ink); margin-bottom: .8rem; }
.site-footer ul { list-style: none; margin: 0; padding: 0; display: grid; gap: .45rem; }
.site-footer a { color: var(--on-ink-muted); text-decoration: none; }
.site-footer a:hover { color: var(--teal); }
.foot-contact { border-top: 1px solid var(--teal); margin-top: 2.5rem; padding-top: 1.25rem; text-align: center; font-size: .9rem; display: grid; gap: .4rem; }
@media (max-width: 860px) { .foot-grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 480px) { .foot-grid { grid-template-columns: 1fr; } }

.mt-1 { margin-top: 1rem; } .mt-2 { margin-top: 2rem; }