/* StrandsOS: "the fabric is the system".
   Midnight/navy surfaces, white text, restrained blue-to-violet. System fonts only and
   no JavaScript: the CSP allows nothing off-origin and no scripts. */
/* Saira (SIL OFL 1.1, assets/fonts/OFL.txt), self-hosted: the CSP allows only same-origin fonts. */
@font-face { font-family: "Saira"; font-style: normal; font-weight: 400; font-display: swap; src: url("/assets/fonts/saira-latin-400-normal.woff2") format("woff2"); }
@font-face { font-family: "Saira"; font-style: normal; font-weight: 600; font-display: swap; src: url("/assets/fonts/saira-latin-600-normal.woff2") format("woff2"); }
@font-face { font-family: "Saira"; font-style: normal; font-weight: 700; font-display: swap; src: url("/assets/fonts/saira-latin-700-normal.woff2") format("woff2"); }
:root {
  --bg: #070B1A; --bg2: #0B1330; --surface: #101936; --surface2: #15204A;
  --border: #24315E; --border-soft: #1A2550;
  --text: #F4F6FF; --soft: #D3D9F2; --muted: #A3ACCF;
  --blue: #5AA2FF; --blue-deep: #3D7DFF; --violet: #9B5CFF; --violet-soft: #B98CFF;
  --demo: #4ADE80; --dev: #5AA2FF; --concept: #C29BFF;
  --grad: linear-gradient(100deg, #6FB8FF 0%, #4F8DFF 45%, #8B6BFF 100%);
  --radius: 14px; --max: 1140px;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--bg); color: var(--text);
  font: 17px/1.65 "Inter", "Noto Sans", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility; }
img, svg { max-width: 100%; }
a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }
:focus-visible { outline: 2px solid var(--blue); outline-offset: 3px; border-radius: 4px; }
.wrap { max-width: var(--max); margin: 0 auto; padding: 0 16px; }
.skip { position: absolute; left: -999px; top: 8px; background: var(--text); color: var(--bg); padding: 8px 14px; border-radius: 8px; z-index: 100; }
.skip:focus { left: 16px; }

/* ---------- header ---------- */
.top { position: sticky; top: 0; z-index: 20; background: rgba(7,11,26,.86);
  backdrop-filter: saturate(140%) blur(10px); border-bottom: 1px solid var(--border-soft); }
.top-row { display: flex; align-items: center; justify-content: space-between; height: 68px; gap: 16px; }
.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--text); font-size: 1.22rem;
  font-weight: 600; letter-spacing: -.01em; }
.brand b { font-weight: 800; background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.brand:hover { text-decoration: none; }
.brand-small { font-size: 1.02rem; }
.nav-wide { display: flex; gap: 26px; }
.nav-wide a, .nav-menu nav a { color: var(--muted); font-size: .96rem; font-weight: 500; }
.nav-wide a:hover, .nav-menu nav a:hover { color: var(--text); text-decoration: none; }
.nav-wide a[aria-current="page"], .nav-menu a[aria-current="page"] { color: var(--text); }
.nav-wide a[aria-current="page"] { box-shadow: inset 0 -2px 0 var(--violet); padding-bottom: 4px; }
.nav-menu { display: none; position: relative; }
.nav-menu summary { list-style: none; cursor: pointer; width: 44px; height: 44px; display: grid; place-content: center; gap: 5px;
  border: 1px solid var(--border); border-radius: 10px; }
.nav-menu summary::-webkit-details-marker { display: none; }
.nav-menu summary span { display: block; width: 18px; height: 2px; background: var(--text); border-radius: 2px; }
.nav-menu nav { position: absolute; right: 0; top: 52px; background: var(--surface); border: 1px solid var(--border);
  border-radius: 12px; padding: 10px; display: grid; min-width: 200px; box-shadow: 0 20px 40px rgba(0,0,0,.4); }
.nav-menu nav a { padding: 10px 12px; border-radius: 8px; }
.nav-menu nav a:hover { background: var(--surface2); }

/* ---------- buttons ---------- */
.btn { display: inline-flex; align-items: center; gap: 8px; padding: 13px 24px; border-radius: 999px; font-weight: 600;
  color: #fff; background: linear-gradient(100deg, #3D7DFF, #7B61FF); border: 0;
  box-shadow: 0 8px 24px rgba(91,97,255,.25); transition: transform .15s, box-shadow .15s; }
.btn:hover { text-decoration: none; transform: translateY(-1px); box-shadow: 0 12px 30px rgba(91,97,255,.35); }
.btn-ghost { background: transparent; box-shadow: none; border: 1px solid var(--border); color: var(--text); }
.btn-ghost:hover { border-color: var(--muted); box-shadow: none; background: var(--surface); }
.cta-row { display: flex; gap: 14px; flex-wrap: wrap; }
.center .cta-row { justify-content: center; }

/* ---------- type ---------- */
h1, h2, h3, .brand, .eyebrow, .tag, .stat b, .btn { font-family: "Saira", "Inter", "Noto Sans", system-ui, sans-serif; }
h1, h2, h3 { letter-spacing: -.01em; }
h1 { font-size: clamp(2.5rem, 7vw, 5rem); line-height: 1.02; margin: 0 0 24px; font-weight: 800; }
h2 { font-size: clamp(1.8rem, 4.2vw, 2.8rem); line-height: 1.1; margin: 0 0 18px; font-weight: 750; }
h3 { font-size: 1.2rem; line-height: 1.3; margin: 0 0 10px; font-weight: 650; }
.grad-text { background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.eyebrow { color: var(--violet-soft); text-transform: uppercase; letter-spacing: .16em; font-size: .78rem; font-weight: 700; margin: 0 0 16px; }
.lead { font-size: clamp(1.08rem, 2.2vw, 1.32rem); color: var(--soft); max-width: 740px; margin: 0 0 32px; }
.center { text-align: center; }
.center .lead, .center .intro { margin-left: auto; margin-right: auto; }
.intro { color: var(--soft); font-size: 1.1rem; max-width: 780px; margin: 0 0 40px; }
.kicker { font-size: 1.15rem; font-weight: 650; color: var(--text); margin: 18px 0 0; }
.kicker::before { content: ""; display: inline-block; width: 22px; height: 2px; background: var(--grad); vertical-align: middle; margin-right: 10px; }
p { margin: 0 0 14px; }

/* ---------- sections ---------- */
section { padding: 96px 0; position: relative; }
section[id] { scroll-margin-top: 70px; }
.alt { background: var(--bg2); border-top: 1px solid var(--border-soft); border-bottom: 1px solid var(--border-soft); }
.hero { padding: 120px 0 110px; overflow: hidden; }
.hero::before { content: ""; position: absolute; inset: -20% -10% auto auto; width: 70%; height: 140%;
  background: radial-gradient(closest-side, rgba(123,97,255,.22), transparent 70%); pointer-events: none; }
.hero::after { content: ""; position: absolute; inset: auto auto -30% -15%; width: 60%; height: 90%;
  background: radial-gradient(closest-side, rgba(61,125,255,.16), transparent 70%); pointer-events: none; }
.hero .wrap { position: relative; z-index: 1; }
.hero-grid { display: grid; grid-template-columns: 1.25fr .9fr; gap: 48px; align-items: center; }
.hero-mark { width: 100%; max-width: 420px; justify-self: center; filter: drop-shadow(0 30px 60px rgba(123,97,255,.35)); }
.page-hero { padding: 96px 0 64px; }
.page-hero h1 { font-size: clamp(2.2rem, 5.5vw, 3.8rem); }

/* ---------- grids & cards ---------- */
.grid { display: grid; gap: 20px; }
.g2 { grid-template-columns: repeat(2, 1fr); } .g3 { grid-template-columns: repeat(3, 1fr); } .g4 { grid-template-columns: repeat(4, 1fr); }
.card { background: var(--surface); border: 1px solid var(--border-soft); border-radius: var(--radius); padding: 28px 26px;
  transition: border-color .2s, transform .2s; }
.card:hover { border-color: var(--border); transform: translateY(-2px); }
.card p { color: var(--soft); font-size: .98rem; margin-bottom: 0; }
.card .tag { margin-bottom: 14px; }
.card h3 a { color: var(--text); }
.alt .card { background: var(--bg); }
.icon { width: 40px; height: 40px; margin-bottom: 16px; }

/* feature rows (Explore) */
.feature { display: grid; grid-template-columns: 1fr 1fr; gap: 56px; align-items: center; padding: 72px 0; border-top: 1px solid var(--border-soft); }
.feature:first-of-type { border-top: 0; }
.feature.flip > :first-child { order: 2; }
.feature h2 { font-size: clamp(1.6rem, 3.4vw, 2.3rem); }
.feature .sub { color: var(--violet-soft); font-weight: 650; margin: -6px 0 16px; font-size: 1.08rem; }
.feature p { color: var(--soft); }
.panel { background: var(--surface); border: 1px solid var(--border-soft); border-radius: 18px; padding: 22px; }
.panel figcaption, figure figcaption { color: var(--muted); font-size: .86rem; margin-top: 12px; }
figure { margin: 0; }
.shot { border-radius: 12px; border: 1px solid var(--border); display: block; width: 100%; height: auto; }

/* tags */
.tag { display: inline-block; font-size: .72rem; font-weight: 700; letter-spacing: .06em; text-transform: uppercase;
  padding: 4px 10px; border-radius: 999px; border: 1px solid; line-height: 1.4; white-space: nowrap; }
.tag-demo { color: var(--demo); border-color: rgba(74,222,128,.45); background: rgba(74,222,128,.08); }
.tag-dev { color: var(--dev); border-color: rgba(90,162,255,.45); background: rgba(90,162,255,.08); }
.tag-concept { color: var(--concept); border-color: rgba(194,155,255,.45); background: rgba(194,155,255,.08); }
.tags { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 14px; }

/* quote band */
.statement { text-align: center; padding: 110px 0; }
.statement p.big { font-size: clamp(1.8rem, 4.6vw, 3.1rem); line-height: 1.15; font-weight: 750; letter-spacing: -.02em; max-width: 900px; margin: 0 auto 18px; }
.statement p.small { color: var(--muted); max-width: 640px; margin: 0 auto; }

/* diagrams (inline SVG) */
.diagram { width: 100%; height: auto; display: block; }
.d-node { fill: var(--surface2); stroke: var(--border); stroke-width: 1.5; }
.d-node-hi { fill: #18245a; stroke: var(--blue); stroke-width: 1.5; }
.d-label { fill: var(--text); font: 600 14px "Inter", "Noto Sans", system-ui, sans-serif; }
.d-sub { fill: var(--muted); font: 12px "Inter", "Noto Sans", system-ui, sans-serif; }
.d-box { fill: none; stroke: var(--border); stroke-width: 1.2; stroke-dasharray: 5 5; }
.d-boxlabel { fill: var(--muted); font: 600 11px "Inter", "Noto Sans", system-ui, sans-serif; letter-spacing: .12em; }
.d-link { fill: none; stroke: url(#dg); stroke-width: 2.5; stroke-linecap: round; }
.d-flow { fill: none; stroke: #fff; stroke-width: 2.5; stroke-linecap: round; stroke-dasharray: 2 26; opacity: .85;
  animation: flow 2.2s linear infinite; }
.d-deny { fill: none; stroke: #6B5A8F; stroke-width: 2; stroke-dasharray: 4 6; }
@keyframes flow { to { stroke-dashoffset: -56; } }

/* lists */
.checks { list-style: none; padding: 0; margin: 0; }
.checks li { padding: 10px 0 10px 34px; position: relative; border-top: 1px solid var(--border-soft); color: var(--soft); }
.checks li:first-child { border-top: 0; }
.checks li::before { content: ""; position: absolute; left: 4px; top: 18px; width: 14px; height: 8px; border-left: 2px solid var(--demo); border-bottom: 2px solid var(--demo); transform: rotate(-45deg); }
.checks.dev li::before { border-color: var(--dev); }
.checks.concept li::before { border-color: var(--concept); }

/* timeline (Journal) */
.timeline { list-style: none; padding: 0; margin: 0; border-left: 2px solid var(--border); }
.timeline li { position: relative; padding: 0 0 36px 30px; }
.timeline li::before { content: ""; position: absolute; left: -8px; top: 6px; width: 14px; height: 14px; border-radius: 50%; background: var(--bg); border: 2px solid var(--violet); }
.timeline time { color: var(--violet-soft); font-weight: 700; font-size: .85rem; letter-spacing: .06em; text-transform: uppercase; }
.timeline h3 { margin: 4px 0 6px; }
.timeline p { color: var(--soft); margin: 0; }
.timeline .lesson { color: var(--muted); font-style: italic; margin-top: 6px; }

/* horizon filter (Future): CSS-only radio filter, no JS */
.filter { display: flex; gap: 10px; flex-wrap: wrap; margin: 0 0 28px; }
.filter input { position: absolute; opacity: 0; pointer-events: none; }
.filter label { cursor: pointer; padding: 9px 18px; border-radius: 999px; border: 1px solid var(--border); color: var(--muted); font-weight: 600; font-size: .92rem; }
.filter input:checked + label { color: var(--text); border-color: var(--violet); background: rgba(155,92,255,.12); }
.filter input:focus-visible + label { outline: 2px solid var(--blue); outline-offset: 3px; }
#h-today:checked ~ .grid .h-next, #h-today:checked ~ .grid .h-horizon,
#h-next:checked ~ .grid .h-today, #h-next:checked ~ .grid .h-horizon,
#h-horizon:checked ~ .grid .h-today, #h-horizon:checked ~ .grid .h-next { display: none; }

/* callout */
.callout { border: 1px solid var(--border); border-left: 3px solid var(--violet); background: var(--surface); border-radius: 12px; padding: 20px 24px; color: var(--soft); }
.callout strong { color: var(--text); }
.refs { font-size: .9rem; color: var(--muted); }
.refs a { color: var(--soft); text-decoration: underline; text-decoration-color: var(--border); }

/* CTA band */
.cta-band { text-align: center; padding: 110px 0; background:
  radial-gradient(50% 70% at 50% 100%, rgba(123,97,255,.22), transparent 70%), var(--bg); border-top: 1px solid var(--border-soft); }
.cta-band p { color: var(--soft); max-width: 640px; margin: 0 auto 30px; font-size: 1.1rem; }

/* footer */
.foot { border-top: 1px solid var(--border-soft); padding: 56px 0 28px; background: var(--bg2); }
.foot-grid { display: grid; grid-template-columns: 1.2fr 1fr 1fr; gap: 32px; }
.foot nav { display: grid; gap: 8px; }
.foot nav a { color: var(--muted); }
.foot-tag { color: var(--muted); margin-top: 10px; }
.foot-contact p { color: var(--muted); margin-bottom: 6px; }
.foot-small { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px; color: var(--muted); font-size: .85rem; margin-top: 40px; padding-top: 22px; border-top: 1px solid var(--border-soft); }
.foot-small .tag { font-size: .62rem; }

/* ---------- responsive ---------- */
@media (max-width: 980px) {
  .g4 { grid-template-columns: repeat(2, 1fr); } .g3 { grid-template-columns: repeat(2, 1fr); }
  .hero-grid, .feature { grid-template-columns: 1fr; gap: 36px; }
  .feature.flip > :first-child { order: 0; }
  .hero-mark { max-width: 260px; }
  .nav-wide { display: none; } .nav-menu { display: block; }
}
@media (max-width: 640px) {
  .g2, .g3, .g4, .foot-grid { grid-template-columns: 1fr; }
  section { padding: 68px 0; } .hero { padding: 72px 0 64px; } .feature { padding: 48px 0; }
  .hero-mark { max-width: 180px; justify-self: start; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .d-flow { animation: none; stroke-dasharray: none; opacity: .25; }
  .card, .btn { transition: none; }
}
.cta-band .cta-row { justify-content: center; }
p.center { margin-top: 36px; }
.case p.how { color: var(--muted); font-size: .92rem; margin-top: 12px; }
.case p.how strong { color: var(--soft); font-weight: 600; }
.case-group { margin-top: 64px; }
.case-group:first-of-type { margin-top: 0; }
.case-group > h2 { font-size: clamp(1.4rem, 3vw, 1.9rem); margin-bottom: 22px; }
.vision-band { text-align: center; padding: 110px 0; border-top: 1px solid var(--border-soft);
  background: radial-gradient(55% 70% at 50% 0%, rgba(155,92,255,.16), transparent 70%), var(--bg); }
.vision-band p:not(.eyebrow) { color: var(--soft); font-size: 1.12rem; max-width: 760px; margin: 0 auto 16px; }
.filter .grid { flex-basis: 100%; margin-top: 18px; }
.stat-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; margin: 8px 0 0; }
.stat { background: var(--surface); border: 1px solid var(--border-soft); border-radius: var(--radius); padding: 22px; }
.stat b { display: block; font-size: 2rem; font-weight: 800; letter-spacing: -.02em; }
.stat span { color: var(--muted); font-size: .92rem; }
@media (max-width: 980px) { .stat-row { grid-template-columns: repeat(2, 1fr); } }

/* v4: concept-board pillars */
.g5 { grid-template-columns: repeat(5, 1fr); }
.pillar { text-align: center; padding: 28px 18px; border-left: 1px solid var(--border-soft); }
.pillar:first-child { border-left: 0; }
.pillar svg { width: 44px; height: 44px; margin-bottom: 14px; }
.pillar h3 { font-size: .86rem; letter-spacing: .22em; text-transform: uppercase; font-weight: 600; margin-bottom: 6px; }
.pillar p { color: var(--muted); font-size: .95rem; margin: 0; }
.pillar a { color: inherit; }
.tagline { font-family: "Saira", system-ui, sans-serif; letter-spacing: .32em; text-transform: uppercase; color: var(--muted); font-size: .9rem; margin: -8px 0 26px; }
@media (max-width: 980px) { .g5 { grid-template-columns: repeat(3, 1fr); } .pillar { border-left: 0; } }
@media (max-width: 640px) { .g5 { grid-template-columns: 1fr 1fr; } }