/* lark-rs showcase — "verified field guide" visual system.
   Light-first paper-and-ink, with a sky/copper/verified accent triad.
   One hand-written stylesheet; no framework, no build step. */

:root {
  --paper: #f3f0e7;
  --paper-raised: #faf8f2;
  --ink: #181a1e;
  --ink-muted: #585b54;
  --sky: #3f718f;
  --sky-deep: #335d77;
  --copper: #9c5333;
  --verified: #336b56;
  --measured: #7a601a;
  --goal: #54578a;
  --open: #834545;
  --rule: #d4cec1;
  --rule-strong: #c0baa9;

  --code-bg: #1d2127;
  --code-ink: #e7e2d6;
  --code-rule: #333a44;

  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --sans: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --maxw: 72rem;
  --pad: clamp(1rem, 4vw, 2.5rem);
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #1a1d22;
    --paper-raised: #21252b;
    --ink: #e9e4d7;
    --ink-muted: #9aa0a8;
    --sky: #7fb0d6;
    --sky-deep: #a7cae6;
    --copper: #d68a64;
    --verified: #6db59a;
    --measured: #c9a24a;
    --goal: #9fa2d6;
    --open: #d08585;
    --rule: #333a44;
    --rule-strong: #424954;
    --code-bg: #11141a;
    --code-rule: #2a313b;
  }
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, .display { font-family: var(--serif); font-weight: 600; line-height: 1.15; }
h2 { font-size: clamp(1.6rem, 3.4vw, 2.3rem); margin: 0 0 .4em; letter-spacing: -0.01em; }
h3 { font-size: 1.2rem; margin: 0 0 .3em; }
p { margin: 0 0 1em; }
a { color: var(--sky-deep); text-decoration-color: var(--rule-strong); text-underline-offset: 2px; }
a:hover { text-decoration-color: currentColor; }

.wrap { max-width: var(--maxw); margin: 0 auto; padding-inline: var(--pad); }
section { padding-block: clamp(3rem, 7vw, 5rem); border-top: 1px solid var(--rule); }
section > p, section > .lede, section > ul { max-width: 42rem; }
.lede { font-size: 1.12rem; color: var(--ink); max-width: 42rem; }
.eyebrow {
  font-family: var(--mono); font-size: .76rem; font-weight: 600; letter-spacing: .16em;
  text-transform: uppercase; color: var(--copper); margin: 0 0 .8em;
}

/* ---- top navigation ---------------------------------------------------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: color-mix(in srgb, var(--paper) 86%, transparent);
  backdrop-filter: saturate(140%) blur(8px);
  border-bottom: 1px solid var(--rule);
}
.nav-inner { display: flex; align-items: center; gap: 1.2rem; min-height: 56px; }
.brand { display: flex; align-items: center; gap: .55rem; font-family: var(--serif); font-weight: 600; font-size: 1.12rem; color: var(--ink); text-decoration: none; }
.brand svg { width: 26px; height: 26px; display: block; }
.brand .rs { color: var(--copper); }
.nav-links { display: flex; gap: 1.1rem; margin-left: auto; font-size: .92rem; }
.nav-links a { color: var(--ink-muted); text-decoration: none; }
.nav-links a:hover { color: var(--ink); }
.nav-cta {
  font-family: var(--mono); font-size: .82rem; padding: .35rem .7rem;
  border: 1px solid var(--rule-strong); border-radius: 6px; color: var(--ink);
  text-decoration: none;
}
.nav-cta:hover { border-color: var(--sky); color: var(--sky-deep); }
@media (max-width: 720px) { .nav-links { display: none; } }

/* ---- hero -------------------------------------------------------------- */
.hero { border-top: none; padding-top: clamp(2.5rem, 6vw, 4.5rem); }
.hero .grid { display: grid; grid-template-columns: 1.4fr 1fr; gap: clamp(1.5rem, 4vw, 3rem); align-items: center; }
@media (max-width: 880px) { .hero .grid { grid-template-columns: 1fr; } }
.hero h1 { font-size: clamp(2.4rem, 6vw, 4rem); letter-spacing: -0.02em; margin: 0 0 .3em; }
.hero h1 .rs { color: var(--copper); }
.hero .tag { font-family: var(--serif); font-size: clamp(1.2rem, 2.6vw, 1.6rem); color: var(--ink); margin: 0 0 .6em; }
.hero p.sub { color: var(--ink-muted); max-width: 38rem; }
.cta-row { display: flex; flex-wrap: wrap; gap: .8rem; margin-top: 1.6rem; }
.btn {
  display: inline-flex; align-items: center; gap: .5rem;
  font-family: var(--sans); font-weight: 500; font-size: .98rem;
  padding: .7rem 1.2rem; border-radius: 8px; text-decoration: none; cursor: pointer;
  border: 1px solid transparent;
}
.btn-primary { background: var(--sky-deep); color: #faf8f2; border-color: color-mix(in srgb, var(--sky-deep) 70%, #000); box-shadow: inset 0 1px 0 color-mix(in srgb, #fff 14%, transparent); }
.btn-primary:hover { background: var(--sky); }
.btn-ghost { border-color: var(--rule-strong); color: var(--ink); background: transparent; }
.btn-ghost:hover { border-color: var(--sky); color: var(--sky-deep); }

.hero-card {
  background: var(--paper-raised); border: 1px solid var(--rule);
  border-radius: 12px; padding: 1.1rem 1.2rem;
  box-shadow: 0 1px 0 var(--rule), 0 18px 40px -28px rgba(0,0,0,.4);
}
.hero-card .cap { font-family: var(--mono); font-size: .72rem; letter-spacing: .12em; text-transform: uppercase; color: var(--ink-muted); margin-bottom: .5rem; }

/* hero field-guide illustration — the artwork's paper ground matches --paper,
   so it sits flush in light mode; in dark mode it reads as a framed plate. */
.hero-fig { margin: 0; text-align: center; }
.hero-fig img { width: 100%; max-width: 380px; height: auto; border-radius: 8px; }
.hero-fig figcaption {
  font-family: var(--mono); font-size: .72rem; letter-spacing: .04em;
  color: var(--ink-muted); margin-top: .4rem;
}
@media (prefers-color-scheme: dark) {
  .hero-fig img { box-shadow: 0 0 0 1px var(--rule), 0 18px 40px -30px rgba(0,0,0,.6); }
}
@media (max-width: 880px) { .hero-fig img { max-width: 300px; } }

/* the canonical grammar, shown above the engine picker + live demo */
.grammar-card { margin: 1.4rem 0; max-width: 640px; }

/* ---- /method/ essay ---------------------------------------------------- */
.essay { max-width: 44rem; margin: 0 auto; padding-block: clamp(2rem, 5vw, 3.5rem); }
.essay section { border-top: 1px solid var(--rule); padding-block: clamp(1.6rem, 4vw, 2.6rem); }
.essay section:first-of-type { border-top: none; }
.essay .essay-title { font-size: clamp(2rem, 5vw, 3.1rem); letter-spacing: -0.015em; margin: 0 0 .5em; }
.essay .lead { font-size: 1.18rem; color: var(--ink); max-width: none; margin-bottom: .4rem; }
.essay h2 { font-size: clamp(1.4rem, 3vw, 1.9rem); margin: 0 0 .5em; }
.essay h3 { font-family: var(--mono); font-size: .92rem; font-weight: 600; letter-spacing: .02em; color: var(--copper); margin: 1.4rem 0 .35rem; }
.essay p, .essay ul { max-width: none; }
.essay ul { padding-left: 1.1rem; display: grid; gap: .55rem; }
.essay li { line-height: 1.6; }
.essay .channels, .essay .table-wrap { max-width: none; }

.pullquote {
  font-family: var(--serif); font-size: clamp(1.3rem, 3vw, 1.7rem); line-height: 1.3;
  color: var(--ink); border-left: 3px solid var(--copper);
  padding: .1rem 0 .1rem 1.1rem; margin: 1.6rem 0;
}
.epigraph {
  margin: 1.4rem 0 0; padding: 1rem 1.2rem; border: 1px solid var(--rule);
  border-radius: 10px; background: var(--paper-raised);
  font-family: var(--serif); font-size: 1.05rem; color: var(--ink-muted);
}
.epigraph span { display: block; margin-top: .5rem; font-family: var(--mono); font-size: .78rem; color: var(--ink-muted); }

.backlink { font-family: var(--mono); font-size: .82rem; margin: 0 0 1.4rem; }
.backlink a { color: var(--ink-muted); text-decoration: none; }
.backlink a:hover { color: var(--sky-deep); }

/* ---- evidence strip ---------------------------------------------------- */
.evidence-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: .9rem; margin-top: 1.4rem; }
.ev {
  background: var(--paper-raised); border: 1px solid var(--rule);
  border-left: 3px solid var(--rule-strong); border-radius: 8px;
  padding: .85rem .95rem; display: block; text-decoration: none; color: inherit;
}
.ev:hover { border-color: var(--rule-strong); transform: translateY(-1px); transition: transform .12s; }
.ev .ev-status { font-family: var(--mono); font-size: .6rem; letter-spacing: .14em; text-transform: uppercase; font-weight: 600; display: block; margin-bottom: .15rem; }
.ev[data-status="verified"] .ev-status { color: var(--verified); }
.ev[data-status="measured"] .ev-status { color: var(--measured); }
.ev[data-status="goal"] .ev-status { color: var(--goal); }
.ev[data-status="open"] .ev-status { color: var(--open); }
.ev .num { font-family: var(--mono); font-size: 1.5rem; font-weight: 600; color: var(--ink); display: block; }
.ev .name { font-size: .86rem; color: var(--ink-muted); }
.ev .arr { float: right; color: var(--ink-muted); opacity: .5; }
.ev[data-status="verified"] { border-left-color: var(--verified); }
.ev[data-status="measured"] { border-left-color: var(--measured); }
.ev[data-status="goal"]     { border-left-color: var(--goal); }
.ev[data-status="open"]     { border-left-color: var(--open); }

/* status pill, used throughout */
.pill {
  display: inline-block; font-family: var(--mono); font-size: .62rem;
  letter-spacing: .14em; text-transform: uppercase; font-weight: 600;
  padding: .12rem .42rem; border-radius: 4px; vertical-align: middle;
  border: 1px solid currentColor;
}
.pill.verified { color: var(--verified); }
.pill.measured { color: var(--measured); }
.pill.goal     { color: var(--goal); }
.pill.open     { color: var(--open); }

/* ---- engine picker ----------------------------------------------------- */
.picker-tabs { display: flex; flex-wrap: wrap; gap: .6rem; margin: 1.4rem 0; }
.picker-tabs button {
  font-family: var(--mono); font-size: .85rem; cursor: pointer;
  padding: .55rem .9rem; border-radius: 8px; background: var(--paper-raised);
  border: 1px solid var(--rule-strong); color: var(--ink-muted);
}
.picker-tabs button[aria-selected="true"] { color: var(--ink); border-color: var(--sky); box-shadow: inset 0 -2px 0 var(--sky); }
.picker-tabs button:hover { color: var(--ink); }
.picker-body { display: grid; grid-template-columns: 1fr 1.1fr; gap: 1.4rem; align-items: start; }
@media (max-width: 820px) { .picker-body { grid-template-columns: 1fr; } }
.picker-desc h3 { font-family: var(--serif); }
.picker-desc .use { color: var(--ink-muted); font-size: .96rem; }
.picker-desc dl { display: grid; grid-template-columns: auto 1fr; gap: .3rem .8rem; margin: 1rem 0 0; font-size: .92rem; }
.picker-desc dt { font-family: var(--mono); color: var(--ink-muted); font-size: .8rem; }
.picker-desc dd { margin: 0; }

/* ---- code blocks ------------------------------------------------------- */
.code {
  position: relative; background: var(--code-bg); color: var(--code-ink);
  border: 1px solid var(--code-rule); border-radius: 10px; overflow: hidden;
}
.code-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: .5rem .8rem; border-bottom: 1px solid var(--code-rule);
  font-family: var(--mono); font-size: .72rem; color: #9aa3b0; letter-spacing: .06em;
}
.code pre { margin: 0; padding: .95rem 1rem; overflow-x: auto; }
.code code { font-family: var(--mono); font-size: .82rem; line-height: 1.55; }
.copy-btn {
  font-family: var(--mono); font-size: .7rem; letter-spacing: .08em; cursor: pointer;
  background: transparent; border: 1px solid var(--code-rule); color: #9aa3b0;
  border-radius: 5px; padding: .2rem .5rem;
}
.copy-btn:hover { color: var(--code-ink); border-color: #4a525e; }
.tok-kw { color: #c98fd0; } .tok-str { color: #9ecb8a; } .tok-fn { color: #7fb0d6; }
.tok-com { color: #6b7280; font-style: italic; } .tok-num { color: #d6a35b; }

/* ---- architecture pipeline -------------------------------------------- */
.pipe { display: grid; grid-template-columns: repeat(4, 1fr); gap: .8rem; margin-top: 1.6rem; }
@media (max-width: 820px) { .pipe { grid-template-columns: 1fr 1fr; } }
.stage {
  position: relative; background: var(--paper-raised); border: 1px solid var(--rule);
  border-radius: 10px; padding: 1rem;
}
.stage .step { font-family: var(--mono); font-size: .72rem; color: var(--copper); letter-spacing: .1em; }
.stage h3 { font-size: 1.05rem; margin: .25rem 0 .35rem; }
.stage p { font-size: .88rem; color: var(--ink-muted); margin: 0; }
.flow { font-family: var(--mono); font-size: .92rem; color: var(--ink-muted); margin-top: 1.4rem; text-align: center; }
.flow b { color: var(--sky-deep); }

/* ---- generic card grids ----------------------------------------------- */
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 1rem; margin-top: 1.6rem; }
.card { background: var(--paper-raised); border: 1px solid var(--rule); border-radius: 10px; padding: 1.1rem; }
.card h3 { font-family: var(--serif); }
.card p { font-size: .92rem; color: var(--ink-muted); margin: 0; }
.card .mono-tag { font-family: var(--mono); font-size: .72rem; color: var(--copper); letter-spacing: .08em; }

/* ---- comparison / fit table ------------------------------------------- */
.table-wrap { overflow-x: auto; margin-top: 1.4rem; }
table { border-collapse: collapse; width: 100%; font-size: .92rem; }
th, td { text-align: left; padding: .65rem .8rem; border-bottom: 1px solid var(--rule); vertical-align: top; }
th { font-family: var(--mono); font-size: .74rem; letter-spacing: .08em; text-transform: uppercase; color: var(--ink-muted); }
tbody tr:hover { background: color-mix(in srgb, var(--paper-raised) 60%, transparent); }

/* ---- decision boundary (method) --------------------------------------- */
.boundary { display: grid; gap: .8rem; margin-top: 1.4rem; }
.lane { display: grid; grid-template-columns: minmax(8rem, 14rem) 1fr; gap: 1rem; align-items: center;
  background: var(--paper-raised); border: 1px solid var(--rule); border-radius: 10px; padding: .9rem 1.1rem; }
@media (max-width: 640px) { .lane { grid-template-columns: 1fr; gap: .3rem; } }
.lane .basis { font-family: var(--mono); font-size: .82rem; color: var(--ink); }
.lane .arrow { color: var(--ink-muted); font-size: .92rem; }
.lane.l1 { border-left: 3px solid var(--verified); }
.lane.l2 { border-left: 3px solid var(--measured); }
.lane.l3 { border-left: 3px solid var(--open); }

/* ---- known limits ------------------------------------------------------ */
.limits { list-style: none; padding: 0; margin: 1.4rem 0 0; display: grid; gap: .7rem; }
.limits li { display: grid; grid-template-columns: auto 1fr; gap: .8rem; align-items: baseline;
  border-bottom: 1px dashed var(--rule); padding-bottom: .7rem; }
.limits .what { color: var(--ink-muted); font-size: .94rem; }

/* ---- footer ------------------------------------------------------------ */
footer { border-top: 1px solid var(--rule); padding-block: 2.5rem; color: var(--ink-muted); font-size: .9rem; }
footer .cols { display: flex; flex-wrap: wrap; gap: 2rem 3rem; }
footer a { color: var(--ink-muted); }
footer a:hover { color: var(--ink); }
footer .legend { display: flex; flex-wrap: wrap; gap: .5rem 1rem; margin-top: 1rem; }

.note { font-size: .82rem; color: var(--ink-muted); margin-top: .8rem; }
.center { text-align: center; }
.hidden { display: none; }

/* ---- live embed (the real WASM playground, iframed) -------------------- */
.demo-frame {
  margin-top: 1.4rem; border: 1px solid var(--rule-strong); border-radius: 12px;
  overflow: hidden; background: var(--paper-raised);
  box-shadow: 0 1px 0 var(--rule), 0 18px 40px -30px rgba(0,0,0,.4);
}
.demo-bar {
  display: flex; align-items: center; gap: .6rem; padding: .55rem .9rem;
  border-bottom: 1px solid var(--rule); font-family: var(--mono); font-size: .74rem;
  color: var(--ink-muted); letter-spacing: .04em;
}
.demo-bar .dot { width: 9px; height: 9px; border-radius: 50%; background: var(--verified); box-shadow: 0 0 0 3px color-mix(in srgb, var(--verified) 18%, transparent); }
.demo-bar .grow { margin-left: auto; }
.demo-bar a { color: var(--sky-deep); text-decoration: none; }
.demo-stage { position: relative; }
.demo-stage iframe { display: block; width: 100%; height: 640px; border: 0; background: var(--paper-raised); }
@media (max-width: 640px) { .demo-stage iframe { height: 760px; } }
.demo-poster {
  display: grid; place-items: center; gap: 1rem; padding: 3rem 1rem; text-align: center;
}
.demo-poster p { color: var(--ink-muted); max-width: 34rem; margin: 0; }
.demo-poster .big { font-family: var(--serif); font-size: 1.3rem; color: var(--ink); margin: 0; }

/* ---- method: numbered routing channels -------------------------------- */
.channels { display: grid; gap: .8rem; margin-top: 1.6rem; }
.channel {
  display: grid; grid-template-columns: 2.4rem 1fr; gap: 1rem; align-items: start;
  background: var(--paper-raised); border: 1px solid var(--rule); border-radius: 10px;
  padding: 1rem 1.1rem; border-left: 3px solid var(--rule-strong);
}
.channel .no { font-family: var(--mono); font-size: 1.1rem; font-weight: 600; color: var(--ink-muted); }
.channel .basis { font-family: var(--mono); font-size: .82rem; letter-spacing: .06em; text-transform: uppercase; color: var(--ink); }
.channel .gloss { color: var(--ink-muted); font-size: .94rem; margin: .15rem 0 .35rem; }
.channel .act { font-weight: 500; }
.channel.c1 { border-left-color: var(--verified); }
.channel.c2 { border-left-color: var(--measured); }
.channel.c3 { border-left-color: var(--open); }
.channel.c1 .act { color: var(--verified); }
.channel.c2 .act { color: var(--measured); }
.channel.c3 .act { color: var(--open); }