/* Readback SI lab sample (prism 2026-10-19). Brand kit v0: ink #102D3B, checked teal #008B86, divider #BDD1D1,
   gray #4D6A73, white field; no gradients. Type: DM Sans, JetBrains Mono for records and commands. */
:root { --ink: #102D3B; --teal: #008B86; --line: #BDD1D1; --gray: #4D6A73; --soft: #F3F7F7; --warn: #A1371C; --teal-text: #00736F;   /* brand teal darkened for small text: 5.4:1 on white (axe) */
  --mono: "JetBrains Mono", ui-monospace, Menlo, Consolas, monospace; }
* { box-sizing: border-box; }
html { scroll-behavior: smooth; } @media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
body { margin: 0; background: #fff; color: var(--ink); font: 400 17px/1.6 "DM Sans", system-ui, sans-serif; }
a { color: var(--teal-text); }
a:focus-visible, button:focus-visible { outline: 2px solid var(--teal); outline-offset: 3px; }
main > section, .bar, .foot { max-width: 1160px; margin: 0 auto; padding-left: clamp(20px, 4vw, 40px); padding-right: clamp(20px, 4vw, 40px); }

.bar { display: flex; align-items: center; justify-content: space-between; gap: 16px; height: 72px; position: sticky; top: 0; background: rgba(255,255,255,.94);
  backdrop-filter: blur(8px); z-index: 10; border-bottom: 1px solid transparent; }
.logo { display: inline-flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; font-size: 21px; font-weight: 700; letter-spacing: -.02em; }
.logo b { font-weight: 700; color: var(--teal); padding-left: 8px; border-left: 1px solid var(--line); margin-left: 2px; }
.bar nav { display: flex; align-items: center; gap: 26px; font-size: 15px; }
.bar nav a { color: var(--ink); text-decoration: none; } .bar nav a:hover { color: var(--teal-text); }
.btn { display: inline-flex; align-items: center; justify-content: center; min-height: 44px; padding: 0 20px; border-radius: 999px; font-weight: 600; text-decoration: none; font-size: 15px; }
.btn.ink { background: var(--ink); color: #fff !important; } .btn.ink:hover { background: var(--teal-text); }
.btn.line { border: 1.5px solid var(--ink); color: var(--ink); } .btn.line:hover { border-color: var(--teal); color: var(--teal-text); }
.btn.big { min-height: 54px; padding: 0 28px; font-size: 16px; }

.hero { padding-top: clamp(56px, 9vw, 112px); padding-bottom: 40px; }
.kicker { margin: 0 0 18px; font-size: 13px; font-weight: 600; letter-spacing: .14em; text-transform: uppercase; color: var(--teal-text); }
.hero h1 { margin: 0; max-width: 16ch; font-size: clamp(2.5rem, 6vw, 4.6rem); line-height: 1.04; letter-spacing: -.035em; font-weight: 700; }
.lede { max-width: 58ch; margin: 24px 0 0; font-size: clamp(18px, 1.6vw, 21px); color: var(--gray); }
.cta { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 34px; }

.demo { padding-top: 40px; padding-bottom: 72px; }
.demo-head h2, .systems h2, .start h2, .research h2 { margin: 0; font-size: clamp(1.7rem, 3vw, 2.4rem); letter-spacing: -.025em; line-height: 1.15; }
.demo-head p, .sub { margin: 10px 0 0; color: var(--gray); max-width: 62ch; }
.qs { display: flex; flex-wrap: wrap; gap: 10px; margin: 28px 0 18px; }
.qs button { font: inherit; font-size: 15px; padding: 10px 16px; border-radius: 999px; border: 1.5px solid var(--line); background: #fff; color: var(--ink); cursor: pointer; min-height: 44px; }
.qs button[aria-selected="true"] { border-color: var(--ink); background: var(--ink); color: #fff; }
.pair { display: grid; gap: 16px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 360px), 1fr)); }
.side { border: 1.5px solid var(--line); border-radius: 16px; padding: 22px 24px 20px; min-height: 196px; background: #fff; }
.side.held { border-color: var(--teal); background: var(--soft); }
.who { margin: 0 0 12px; font-size: 13px; font-weight: 600; letter-spacing: .1em; text-transform: uppercase; color: var(--gray); }
.held .who { color: var(--teal-text); }
.ans { margin: 0; min-height: 3.2em; font-size: clamp(19px, 1.9vw, 23px); line-height: 1.4; font-weight: 500; }
.src { margin: 12px 0 0; min-height: 1.4em; font: 400 13.5px/1.4 var(--mono); color: var(--gray); }
.tag { display: inline-block; margin: 14px 0 0; padding: 4px 12px; border-radius: 999px; font-size: 13.5px; font-weight: 600; opacity: 0; transition: opacity .3s; background: #FBEDE8; color: var(--warn); }
.tag.ok { background: #DDF1EF; color: #006A66; } .tag.on { opacity: 1; }
@media (prefers-reduced-motion: reduce) { .tag { transition: none; } }
.note { margin: 14px 0 0; font-size: 14px; color: var(--gray); min-height: 1.4em; }
.proof { list-style: none; margin: 34px 0 0; padding: 0; display: grid; gap: 14px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 420px), 1fr)); }
.proof li { border-top: 2px solid var(--ink); padding-top: 14px; font-size: 15.5px; color: var(--gray); }
.proof b { color: var(--ink); }

.systems { padding-top: 72px; padding-bottom: 72px; border-top: 1px solid var(--line); }
.tiles { display: grid; gap: 16px; margin-top: 30px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 250px), 1fr)); }
.tiles article { border: 1.5px solid var(--line); border-radius: 16px; padding: 22px; display: flex; flex-direction: column; }
.tiles .n { font: 500 13px var(--mono); color: var(--teal-text); }
.tiles h3 { margin: 10px 0 8px; font-size: 20px; letter-spacing: -.01em; }
.tiles p { margin: 0 0 16px; font-size: 15.5px; color: var(--gray); }
.tiles a { margin-top: auto; font-weight: 600; text-decoration: none; } .tiles a::after { content: " \2192"; }
.tiles a:hover { text-decoration: underline; }

.start { padding-top: 72px; padding-bottom: 72px; display: grid; gap: 36px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 380px), 1fr)); align-items: start; border-top: 1px solid var(--line); }
.start p { color: var(--gray); max-width: 46ch; } .small { font-size: 14px; }
.cmds { list-style: none; margin: 0; padding: 0; display: grid; gap: 10px; counter-reset: c; }
.cmds li { background: var(--ink); color: #fff; border-radius: 14px; padding: 14px 18px; counter-increment: c; }
.cmds span { display: block; font-size: 13px; color: #9FC9C6; margin-bottom: 4px; } .cmds span::before { content: counter(c) ". "; }
.cmds code { font: 500 15px/1.4 var(--mono); }

.research { padding-top: 72px; padding-bottom: 88px; border-top: 1px solid var(--line); }
.papers { display: grid; gap: 12px; margin-top: 26px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 480px), 1fr)); }
.papers a { display: block; padding: 18px 20px; border: 1.5px solid var(--line); border-radius: 14px; color: var(--ink); text-decoration: none; font-weight: 500; line-height: 1.4; }
.papers a:hover { border-color: var(--teal-text); }
.papers span { display: block; margin-bottom: 6px; font-size: 13px; font-weight: 600; color: var(--teal-text); }

.foot { padding-top: 36px; padding-bottom: 48px; border-top: 1px solid var(--line); color: var(--gray); }
.foot p { margin: 8px 0 0; } .foot img { display: block; }
@media (max-width: 720px) { .bar nav a:not(.btn) { display: none; } }