/* ============================================================
   code-native agent — build log
   Aesthetic: the agent's notebook / annotated trace.
   Warm paper + near-black ink. ARC 16-color palette ONLY in grids.
   ============================================================ */

:root {
  --paper:   #f5f3ec;
  --paper-2: #efece2;
  --ink:     #17150f;
  --ink-2:   #4a4636;
  --ink-3:   #6f6a58;
  --rule:    #d8d3c2;
  --rule-2:  #c7c1ad;
  --accent:  #921231; /* arc index 13, used only as a thin ink-accent for rules/badges */

  /* ARC-AGI 16 color palette (index -> hex) */
  --c0:  #FFFFFF; --c1:  #CCCCCC; --c2:  #999999; --c3:  #666666;
  --c4:  #333333; --c5:  #000000; --c6:  #E53AA3; --c7:  #FF7BCC;
  --c8:  #F93C31; --c9:  #1E93FF; --c10: #88D8F1; --c11: #FFDC00;
  --c12: #FF851B; --c13: #921231; --c14: #4FCC30; --c15: #A356D6;

  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --mono:  "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.62;
  /* faint ruled-notebook texture */
  background-image:
    repeating-linear-gradient(
      to bottom,
      transparent 0,
      transparent 31px,
      rgba(146, 18, 49, 0.035) 31px,
      rgba(146, 18, 49, 0.035) 32px
    );
}

/* ---------- sticky nav ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 1.2rem;
  flex-wrap: wrap;
  padding: 0.55rem 1.4rem;
  background: rgba(245, 243, 236, 0.93);
  backdrop-filter: blur(4px);
  border-bottom: 1px solid var(--rule-2);
}
.nav .brand {
  font-family: var(--mono);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--ink);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.nav a {
  font-family: var(--mono);
  font-size: 0.74rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-3);
  text-decoration: none;
  padding: 0.15rem 0;
  border-bottom: 1.5px solid transparent;
  transition: color .15s, border-color .15s;
}
.nav a:hover { color: var(--ink); border-bottom-color: var(--accent); }
.nav .spacer { flex: 1 1 auto; }

/* recurring signature glyph: observe -> run_python -> act */
.sigloop {
  font-family: var(--mono);
  font-size: 0.66rem;
  color: var(--ink-3);
  white-space: nowrap;
}
.sigloop b { color: var(--accent); font-weight: 700; }
.sigloop .arr { color: var(--rule-2); padding: 0 0.15rem; }

/* ---------- layout ---------- */
.wrap {
  max-width: 980px;
  margin: 0 auto;
  padding: 0 1.4rem 6rem;
}

header.hero {
  max-width: 980px;
  margin: 0 auto;
  padding: 3.4rem 1.4rem 1.6rem;
}
.kicker {
  font-family: var(--mono);
  font-size: 0.74rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 0.9rem;
}
h1 {
  font-family: var(--serif);
  font-weight: 600;
  font-size: clamp(2rem, 5vw, 3.1rem);
  line-height: 1.08;
  letter-spacing: -0.01em;
  margin: 0 0 1rem;
}
.lede {
  font-size: 1.18rem;
  color: var(--ink-2);
  max-width: 64ch;
  margin: 0 0 1.4rem;
}

.stamp {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
  border: 1.5px solid var(--accent);
  border-radius: 3px;
  padding: 0.3rem 0.7rem;
  transform: rotate(-1.4deg);
  background: rgba(146,18,49,0.04);
}
.stamp .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--accent); }

/* ---------- sections ---------- */
section { padding-top: 2.6rem; margin-top: 1.4rem; scroll-margin-top: 72px; }
.sec-head {
  display: flex;
  align-items: baseline;
  gap: 0.8rem;
  border-bottom: 2px solid var(--ink);
  padding-bottom: 0.4rem;
  margin-bottom: 1.4rem;
}
.sec-num {
  font-family: var(--mono);
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--accent);
}
.sec-head h2 {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1.7rem;
  margin: 0;
}
.sec-head .tag {
  font-family: var(--mono);
  font-size: 0.68rem;
  color: var(--ink-3);
  margin-left: auto;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

h3 {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1.18rem;
  margin: 1.8rem 0 0.5rem;
}
p { margin: 0.7rem 0; }
.muted { color: var(--ink-3); }
strong { font-weight: 700; }
em.term { font-style: italic; color: var(--ink-2); }

code.inl {
  font-family: var(--mono);
  font-size: 0.84em;
  background: var(--paper-2);
  border: 1px solid var(--rule);
  border-radius: 3px;
  padding: 0.05em 0.35em;
}

/* ---------- badges ---------- */
.badge {
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  padding: 0.1rem 0.45rem;
  border-radius: 3px;
  border: 1.5px solid;
  white-space: nowrap;
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
}
.badge.fail    { color: #7a1020; border-color: #7a1020; background: rgba(249,60,49,0.07); }
.badge.run     { color: #8a5a00; border-color: #c08400; background: rgba(255,220,0,0.12); }
.badge.proven  { color: #1f6a1f; border-color: #2f8a2f; background: rgba(79,204,48,0.12); }
.badge.open    { color: var(--ink-3); border-color: var(--rule-2); background: var(--paper-2); }

/* ---------- figure / svg ---------- */
figure.diagram {
  margin: 1.6rem 0;
  padding: 1.1rem 1.1rem 0.4rem;
  background: var(--paper-2);
  border: 1px solid var(--rule-2);
  border-radius: 6px;
}
figure.diagram svg { display: block; width: 100%; height: auto; }
figure.diagram figcaption {
  font-family: var(--mono);
  font-size: 0.74rem;
  color: var(--ink-3);
  line-height: 1.5;
  padding: 0.7rem 0.2rem 0.4rem;
  border-top: 1px solid var(--rule);
  margin-top: 0.6rem;
}
figure.diagram figcaption b { color: var(--ink); font-weight: 700; }

/* svg shared text styling via classes (defined inline too) */
.svgwrap { overflow-x: auto; }

/* ---------- code blocks (terminal frame) ---------- */
.term {
  margin: 1.3rem 0;
  border: 1px solid var(--ink);
  border-radius: 6px;
  overflow: hidden;
  background: #1c1a14;
}
.term .bar {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.45rem 0.7rem;
  background: #262219;
  border-bottom: 1px solid #38332650;
}
.term .bar .b { width: 11px; height: 11px; border-radius: 50%; display: inline-block; }
.term .bar .b1 { background: var(--c8); }
.term .bar .b2 { background: var(--c11); }
.term .bar .b3 { background: var(--c14); }
.term .bar .title {
  font-family: var(--mono);
  font-size: 0.7rem;
  color: #b9b29a;
  margin-left: 0.4rem;
  letter-spacing: 0.03em;
}
.term pre {
  margin: 0;
  padding: 0.95rem 1.1rem;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 0.8rem;
  line-height: 1.6;
  color: #e7e2d2;
}
.term pre .c { color: #7d7762; }       /* comment */
.term pre .k { color: #88D8F1; }       /* keyword */
.term pre .s { color: #FFDC00; }       /* string  */
.term pre .f { color: #FF7BCC; }       /* func    */
.term pre .n { color: #4FCC30; }       /* num     */

/* ---------- ARC grids (CSS-grid cells) ---------- */
.gridfig {
  display: inline-block;
  margin: 0.6rem 1.4rem 0.6rem 0;
  vertical-align: top;
}
.gridfig .cap {
  font-family: var(--mono);
  font-size: 0.7rem;
  color: var(--ink-3);
  margin-top: 0.45rem;
  max-width: 30ch;
}
.arcgrid {
  display: grid;
  gap: 1px;
  background: var(--rule-2);
  border: 2px solid var(--ink);
  padding: 1px;
  border-radius: 2px;
  image-rendering: pixelated;
}
.arcgrid > i { display: block; width: 100%; height: 100%; }

/* color classes for cells */
.k0{background:var(--c0)} .k1{background:var(--c1)} .k2{background:var(--c2)}
.k3{background:var(--c3)} .k4{background:var(--c4)} .k5{background:var(--c5)}
.k6{background:var(--c6)} .k7{background:var(--c7)} .k8{background:var(--c8)}
.k9{background:var(--c9)} .k10{background:var(--c10)} .k11{background:var(--c11)}
.k12{background:var(--c12)} .k13{background:var(--c13)} .k14{background:var(--c14)}
.k15{background:var(--c15)}

.gridrow { display: flex; flex-wrap: wrap; align-items: flex-start; gap: 0.4rem 1.4rem; }

/* palette legend */
.palette { display: flex; flex-wrap: wrap; gap: 0.5rem 0.8rem; margin: 1rem 0; }
.palette .pi {
  display: flex; align-items: center; gap: 0.35rem;
  font-family: var(--mono); font-size: 0.68rem; color: var(--ink-3);
}
.palette .sw { width: 14px; height: 14px; border: 1px solid var(--rule-2); border-radius: 2px; }

/* ---------- comparison table ---------- */
.tblwrap { overflow-x: auto; margin: 1.3rem 0; }
table.cmp {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.86rem;
}
table.cmp th, table.cmp td {
  text-align: left;
  padding: 0.55rem 0.7rem;
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
}
table.cmp thead th {
  font-family: var(--mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--ink);
  border-bottom: 2px solid var(--ink);
}
table.cmp tbody th {
  font-family: var(--mono);
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--ink-2);
  white-space: nowrap;
}
table.cmp tbody tr:last-child td, table.cmp tbody tr:last-child th { border-bottom: none; }
table.cmp .ours { background: rgba(146,18,49,0.05); }
table.cmp col.ourscol { background: rgba(146,18,49,0.04); }

/* ---------- failure ladder timeline ---------- */
.ladder { list-style: none; margin: 1.4rem 0; padding: 0; position: relative; }
.ladder::before {
  content: "";
  position: absolute;
  left: 13px; top: 6px; bottom: 6px;
  width: 2px;
  background: var(--rule-2);
}
.ladder li {
  position: relative;
  padding: 0 0 1.5rem 2.6rem;
}
.ladder li .node {
  position: absolute;
  left: 4px; top: 2px;
  width: 20px; height: 20px;
  border-radius: 50%;
  background: var(--paper);
  border: 2px solid var(--ink);
  display: flex; align-items: center; justify-content: center;
  font-family: var(--mono); font-size: 0.66rem; font-weight: 700;
}
.ladder li.f .node { border-color: #7a1020; color: #7a1020; }
.ladder li.r .node { border-color: #c08400; color: #8a5a00; }
.ladder li h4 {
  font-family: var(--mono);
  font-size: 0.82rem;
  margin: 0 0 0.25rem;
  display: flex; align-items: center; gap: 0.6rem; flex-wrap: wrap;
}
.ladder li .verdict {
  font-style: italic;
  color: var(--ink-2);
  font-family: var(--serif);
}

/* ---------- callout ---------- */
.callout {
  margin: 1.4rem 0;
  padding: 1rem 1.2rem;
  border-left: 4px solid var(--accent);
  background: var(--paper-2);
  border-radius: 0 5px 5px 0;
}
.callout .lab {
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--accent);
  margin-bottom: 0.3rem;
}

/* two-column result lists */
.cols2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1.4rem; margin: 1.2rem 0; }
.cols2 h3 { margin-top: 0; }
.cols2 ul { margin: 0.4rem 0 0; padding-left: 1.1rem; }
.cols2 li { margin: 0.45rem 0; }

footer {
  max-width: 980px;
  margin: 3rem auto 0;
  padding: 1.6rem 1.4rem 3rem;
  border-top: 1px solid var(--rule-2);
  font-family: var(--mono);
  font-size: 0.74rem;
  color: var(--ink-3);
}

/* ---------- responsive ---------- */
@media (max-width: 720px) {
  body { font-size: 16px; }
  .cols2 { grid-template-columns: 1fr; }
  .nav .sigloop { display: none; }
  .gridfig { margin-right: 0.8rem; }
  header.hero { padding-top: 2.2rem; }
}