/* Silt — sedimentary strata. Warm ink, dried-silt bone, mineral ochre,
   river green. Fraunces (charter voice) / Plex Sans (body) / Plex Mono
   (data). The through-line is deposition: layers accumulating downward. */

:root {
  --ink:      #14110e;   /* warm near-black — wet sediment */
  --ink-2:    #1c1813;   /* raised surface */
  --ink-3:    #241f18;   /* card */
  --stratum:  #2f2820;   /* bedding-plane hairlines / borders */
  --bone:     #ece4d5;   /* dried silt, pale */
  --drab:     #9c907b;   /* clay, dimmed text */
  --ochre:    #d6a24a;   /* the silt glint — primary accent */
  --ochre-dk: #b58433;
  --river:    #79a392;   /* the water that carries it — healthy/available */
  --rust:     #b8703f;   /* oxidised — warnings, rare */

  --display: "Fraunces", Georgia, "Times New Roman", serif;
  --body: "IBM Plex Sans", system-ui, -apple-system, sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, monospace;

  --measure: 62ch;
  --edge: clamp(1.2rem, 5vw, 6rem);
}

* { box-sizing: border-box; margin: 0; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }

body {
  background: var(--ink);
  color: var(--bone);
  font-family: var(--body);
  font-size: 17px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* Fine sediment grain over everything — the particulate feel. */
body::before {
  content: "";
  position: fixed; inset: 0; z-index: 9999; pointer-events: none;
  opacity: 0.05; mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

a { color: var(--ochre); text-decoration: none; }
a:hover { color: var(--bone); }

/* ---- type ---- */
h1, h2, h3 { font-family: var(--display); font-weight: 400; line-height: 1.05; letter-spacing: -0.01em; }
.eyebrow {
  font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.28em;
  text-transform: uppercase; color: var(--ochre);
}
.mono { font-family: var(--mono); }
.dim { color: var(--drab); }

/* ---- shell ---- */
nav {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 2rem;
  padding: 1.1rem var(--edge);
  background: color-mix(in srgb, var(--ink) 82%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--stratum);
}
.wordmark {
  font-family: var(--display); font-size: 1.5rem; font-weight: 500;
  letter-spacing: -0.02em; color: var(--bone);
}
.wordmark b { color: var(--ochre); font-weight: 500; }
nav .spacer { flex: 1; }
nav a { color: var(--drab); font-size: 0.92rem; }
nav a:hover { color: var(--bone); }
nav .ghost { border: 1px solid var(--stratum); border-radius: 2px; padding: 0.4rem 0.9rem; }
@media (max-width: 720px) { nav .hide-sm { display: none; } }

section { padding: clamp(4rem, 9vw, 8rem) var(--edge); position: relative; }
.wrap { max-width: 1120px; margin: 0 auto; }
.measure { max-width: var(--measure); }

/* bedding-plane divider with a stratigraphic annotation */
.plane { border-top: 1px solid var(--stratum); }
.stratum-label {
  font-family: var(--mono); font-size: 0.7rem; letter-spacing: 0.2em;
  color: var(--drab); text-transform: uppercase;
  display: flex; gap: 0.8rem; align-items: center; margin-bottom: 2.4rem;
}
.stratum-label::after { content: ""; height: 1px; flex: 1; background: var(--stratum); }

/* ---- hero ---- */
.hero { padding-top: clamp(4rem, 10vw, 9rem); padding-bottom: clamp(4rem, 8vw, 7rem); }
.hero .thesis {
  font-family: var(--display);
  font-size: clamp(2.9rem, 8.5vw, 6.4rem);
  line-height: 0.98; letter-spacing: -0.03em; max-width: 15ch;
  font-optical-sizing: auto;
}
.hero .thesis em { font-style: italic; color: var(--ochre); }
.hero .sub { margin-top: 1.8rem; max-width: 54ch; font-size: 1.18rem; color: var(--drab); }
.hero .sub b { color: var(--bone); font-weight: 500; }
.cta-row { display: flex; flex-wrap: wrap; gap: 0.8rem; margin-top: 2.4rem; }

.btn {
  font-family: var(--body); font-size: 0.98rem; font-weight: 500;
  padding: 0.72rem 1.4rem; border-radius: 2px; cursor: pointer;
  border: 1px solid var(--ochre); background: var(--ochre); color: var(--ink);
  display: inline-flex; align-items: center; gap: 0.5rem; transition: transform 0.12s ease;
}
.btn:hover { color: var(--ink); transform: translateY(-1px); }
.btn.ghost { background: transparent; color: var(--bone); border-color: var(--stratum); }
.btn.ghost:hover { border-color: var(--ochre); color: var(--ochre); }

.genesis {
  margin-top: 3.2rem; padding: 1rem 1.2rem; border: 1px solid var(--stratum);
  border-left: 2px solid var(--ochre); border-radius: 2px; background: var(--ink-2);
  font-family: var(--mono); font-size: 0.78rem; color: var(--drab);
  max-width: 62ch; overflow-x: auto;
}
.genesis b { color: var(--river); font-weight: 400; }

/* the strata column: layered bands, a riverbank cross-section */
.core {
  position: absolute; top: 0; right: var(--edge); bottom: 0; width: 74px;
  display: none; border-left: 1px solid var(--stratum); border-right: 1px solid var(--stratum);
}
@media (min-width: 1000px) { .hero .core { display: block; } }
.core i { display: block; }

/* ---- principles as strata ---- */
.strata { display: grid; gap: 0; margin-top: 1rem; }
.layer {
  display: grid; grid-template-columns: minmax(0,1fr) minmax(0,1.4fr); gap: 2rem;
  padding: 2.2rem 0; border-top: 1px solid var(--stratum); align-items: baseline;
}
.layer:last-child { border-bottom: 1px solid var(--stratum); }
.layer h3 { font-size: clamp(1.5rem, 3vw, 2rem); }
.layer .k { font-family: var(--mono); font-size: 0.72rem; color: var(--ochre); letter-spacing: 0.18em; text-transform: uppercase; margin-bottom: 0.7rem; }
.layer p { color: var(--drab); }
.layer p b { color: var(--bone); font-weight: 500; }
@media (max-width: 720px) { .layer { grid-template-columns: 1fr; gap: 0.6rem; } }

/* ---- pipeline (a real sequence → lettered stages allowed) ---- */
.flow { display: grid; grid-template-columns: repeat(5, 1fr); gap: 1px; background: var(--stratum); border: 1px solid var(--stratum); border-radius: 2px; margin-top: 2rem; }
.flow .step { background: var(--ink-2); padding: 1.4rem 1.1rem; }
.flow .step .s { font-family: var(--mono); color: var(--ochre); font-size: 0.72rem; letter-spacing: 0.15em; }
.flow .step h4 { font-family: var(--display); font-weight: 400; font-size: 1.15rem; margin: 0.5rem 0 0.4rem; }
.flow .step p { font-size: 0.86rem; color: var(--drab); line-height: 1.5; }
@media (max-width: 860px) { .flow { grid-template-columns: 1fr 1fr; } }
@media (max-width: 480px) { .flow { grid-template-columns: 1fr; } }

/* ---- run a node ---- */
.split { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: clamp(2rem,5vw,4.5rem); align-items: start; }
@media (max-width: 820px) { .split { grid-template-columns: 1fr; } }
.rules { list-style: none; }
.rules li { padding: 0.7rem 0; border-top: 1px solid var(--stratum); display: flex; gap: 0.9rem; color: var(--drab); }
.rules li b { color: var(--bone); font-weight: 500; }
.rules li::before { content: "▸"; color: var(--ochre); }

pre.code {
  background: var(--ink-2); border: 1px solid var(--stratum); border-radius: 2px;
  padding: 1.1rem 1.2rem; overflow-x: auto; font-family: var(--mono); font-size: 0.82rem;
  color: var(--bone); line-height: 1.65;
}
pre.code .c { color: var(--drab); }
pre.code .o { color: var(--ochre); }
pre.code .g { color: var(--river); }

/* the chain as strata */
.chain { margin-top: 1.5rem; border: 1px solid var(--stratum); border-radius: 2px; overflow: hidden; }
.block { display: grid; grid-template-columns: auto 1fr auto; gap: 1rem; align-items: center;
  padding: 0.9rem 1.2rem; border-top: 1px solid var(--stratum); background: var(--ink-2); }
.block:first-child { border-top: 0; }
.block.gen { background: color-mix(in srgb, var(--ochre) 9%, var(--ink-2)); }
.block .h { font-family: var(--mono); font-size: 0.7rem; color: var(--drab); }
.block .lbl { font-family: var(--mono); font-size: 0.72rem; letter-spacing: 0.12em; color: var(--ochre); }
.block .att { font-family: var(--mono); font-size: 0.72rem; color: var(--river); }

/* ---- downloads ---- */
.dls { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin-top: 2rem; }
@media (max-width: 720px) { .dls { grid-template-columns: 1fr; } }
.dl { background: var(--ink-2); border: 1px solid var(--stratum); border-radius: 2px; padding: 1.4rem; }
.dl h4 { font-family: var(--display); font-weight: 400; font-size: 1.3rem; margin-bottom: 0.3rem; }
.dl p { color: var(--drab); font-size: 0.85rem; margin-bottom: 1rem; }

/* ---- boundary (what Silt is not) ---- */
.boundary { background: var(--ink-2); border-top: 1px solid var(--stratum); border-bottom: 1px solid var(--stratum); }
.boundary h2 { font-size: clamp(1.8rem, 4vw, 2.6rem); max-width: 20ch; }
.boundary .cols { display: grid; grid-template-columns: 1fr 1fr; gap: 2.5rem; margin-top: 2rem; }
@media (max-width: 720px) { .boundary .cols { grid-template-columns: 1fr; } }
.boundary .cols div h4 { font-family: var(--mono); font-size: 0.78rem; letter-spacing: 0.14em; text-transform: uppercase; margin-bottom: 0.6rem; }
.is h4 { color: var(--river); }
.isnot h4 { color: var(--rust); }
.boundary p { color: var(--drab); }

/* ---- footer ---- */
footer { padding: 4rem var(--edge) 3rem; border-top: 1px solid var(--stratum); }
footer .cols { display: flex; flex-wrap: wrap; gap: 3rem; justify-content: space-between; }
footer .line { font-family: var(--display); font-size: 1.4rem; max-width: 22ch; }
footer nav { position: static; background: none; border: 0; backdrop-filter: none; padding: 0; flex-direction: column; gap: 0.5rem; align-items: flex-start; }
footer .meta { font-family: var(--mono); font-size: 0.72rem; color: var(--drab); margin-top: 2.5rem; display: flex; flex-wrap: wrap; gap: 0.4rem 1.5rem; }

/* ---- docs / node page utility ---- */
.doc { max-width: 820px; margin: 0 auto; padding: clamp(3rem,7vw,6rem) var(--edge); }
.doc h1 { font-size: clamp(2.4rem, 6vw, 3.6rem); margin-bottom: 0.5rem; }
.doc h2 { font-size: 1.7rem; margin: 3rem 0 1rem; padding-top: 1.4rem; border-top: 1px solid var(--stratum); }
.doc h3 { font-family: var(--mono); font-weight: 500; font-size: 0.95rem; letter-spacing: 0.02em; color: var(--ochre); margin: 1.8rem 0 0.6rem; }
.doc p { color: var(--drab); margin: 0.8rem 0; max-width: var(--measure); }
.doc p b, .doc li b { color: var(--bone); font-weight: 500; }
.doc ul { color: var(--drab); margin: 0.8rem 0 0.8rem 1.2rem; }
.doc li { margin: 0.35rem 0; }
.doc .lead { font-size: 1.2rem; color: var(--bone); font-family: var(--display); line-height: 1.4; }
.doc table { width: 100%; border-collapse: collapse; margin: 1rem 0; font-size: 0.9rem; }
.doc th { text-align: left; color: var(--drab); font-weight: 500; padding: 0.5rem 0.8rem; border-bottom: 1px solid var(--stratum); }
.doc td { padding: 0.5rem 0.8rem; border-bottom: 1px solid var(--stratum); vertical-align: top; }
.doc td.mono, .doc th.mono { font-family: var(--mono); font-size: 0.82rem; }

:focus-visible { outline: 2px solid var(--ochre); outline-offset: 3px; }

/* settle-in on load (respect reduced motion) */
@keyframes settle { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: none; } }
.settle { animation: settle 0.7s cubic-bezier(.2,.7,.2,1) both; }
.settle-2 { animation-delay: 0.08s; }
.settle-3 { animation-delay: 0.16s; }
.settle-4 { animation-delay: 0.24s; }
@media (prefers-reduced-motion: reduce) { .settle, .settle-2, .settle-3, .settle-4 { animation: none; } }