/* ---------------------------------------------------------------
   LLM4ABM — structure and typography

   Colour values live in themes.css as CSS custom properties, swapped
   at runtime via the [data-theme] attribute on <html>. This file is
   colour-scheme agnostic: it only reads var(--…) tokens.

   Design language: flat surfaces, plain borders, square corners
   throughout (no border-radius anywhere) — matching the CSS Society
   house style.
   ------------------------------------------------------------- */

:root {
  --font-display: "Fraunces", Georgia, serif;
  --font-body: "IBM Plex Sans", "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", "Courier New", monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 1.05rem;
  line-height: 1.65;
}

a { color: var(--link); }
a:hover { text-decoration-thickness: 2px; }

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

h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 600;
  letter-spacing: -0.01em;
  line-height: 1.1;
  margin: 0 0 0.5em;
}

.eyebrow {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--secondary);
  margin-bottom: 0.6em;
}

.eyebrow-light { color: var(--panel-ink-muted); }

.wrap {
  max-width: 68rem;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ---------- header ---------- */

.site-header {
  background: var(--panel);
  color: var(--panel-ink);
  border-bottom: 1px solid var(--panel-line);
}

.site-header .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.2rem;
  flex-wrap: wrap;
  padding-top: 1rem;
  padding-bottom: 1rem;
}

.site-title {
  font-family: var(--font-display);
  font-size: 1.15rem;
  color: var(--title-ink);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.site-title .dot,
.footer-title .dot { color: var(--accent); }

.header-right {
  display: flex;
  align-items: center;
  gap: 1.6rem;
  flex-wrap: wrap;
}

.site-nav { display: flex; gap: 1.4rem; flex-wrap: wrap; }

.site-nav a {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--panel-ink);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  padding-bottom: 3px;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  border-bottom-color: var(--accent);
}

/* ---------- theme switcher ---------- */

.theme-switcher {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.theme-switcher .theme-label {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--panel-ink-muted);
  margin-right: 0.1rem;
}

.theme-swatches {
  display: flex;
  gap: 0.4rem;
  list-style: none;
  margin: 0;
  padding: 0;
}

.theme-swatch {
  width: 1.3rem;
  height: 1.3rem;
  padding: 0;
  border: 1px solid var(--panel-line);
  cursor: pointer;
  background: linear-gradient(135deg, var(--sw-primary) 50%, var(--sw-secondary) 50%);
}

.theme-swatch[aria-pressed="true"] {
  outline: 2px solid var(--panel-ink);
  outline-offset: 2px;
}

/* ---------- hero ---------- */

.hero {
  background: var(--panel);
  color: var(--panel-ink);
}

.hero .wrap {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 2.5rem;
  align-items: center;
  padding-top: 4rem;
  padding-bottom: 4rem;
}

.hero h1 {
  font-size: clamp(2.2rem, 4.4vw, 3.4rem);
  color: var(--title-ink);
}

.hero p.subheading {
  font-family: var(--font-display);
  font-weight: 500;
  font-size: clamp(1.05rem, 1.8vw, 1.3rem);
  color: var(--title-ink);
  margin: 0 0 0.9em;
  max-width: 34rem;
}

.hero p.lede {
  font-size: 1.15rem;
  color: var(--panel-ink-muted);
  max-width: 34rem;
}

.hero .cta-row { display: flex; gap: 1rem; margin-top: 1.6rem; flex-wrap: wrap; }

.btn {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  text-decoration: none;
  padding: 0.75rem 1.3rem;
  border: 1px solid currentColor;
}

.btn-primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.btn-primary:hover { background: var(--primary); border-color: var(--primary); color: #fff; }

.btn-ghost { color: var(--panel-ink); }
.btn-ghost:hover { background: var(--panel-hover); }

/* ---------- affiliation strip ---------- */

.affiliation-strip {
  background: var(--tint);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.affiliation-strip-inner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.55rem;
  padding: 0.85rem 0;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  letter-spacing: 0.02em;
  color: var(--panel-ink-muted);
}

.affiliation-strip-link { display: inline-flex; align-items: center; line-height: 0; }

.affiliation-strip-logo {
  display: block;
  height: 1.6rem;
  width: auto;
  border-radius: 2px;
  vertical-align: middle;
}

/* ---------- signature graphic ---------- */

.signature-wrap { width: 100%; }
.signature { width: 100%; height: auto; display: block; }

.sig-edges-base line {
  stroke: var(--panel-line);
  stroke-width: 3;
  stroke-opacity: 0.45;
}

.sig-nodes-base rect {
  fill: var(--panel-ink);
  fill-opacity: 0.12;
  stroke: var(--panel-line);
  stroke-opacity: 0.6;
  stroke-width: 2;
}

.sig-highlights {
  opacity: 1;
  transition: opacity 0.6s ease;
}

.sig-highlights.fade { opacity: 0; }

.sig-highlights .sig-node-active { fill: var(--panel-ink); }

.sig-highlights .sig-edge-active {
  stroke: var(--signature-line);
  stroke-width: 4;
  fill: none;
}

@media (prefers-reduced-motion: reduce) {
  .sig-highlights { transition: none; }
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ---------- sections ---------- */

section.block { padding: 3.5rem 0; }
section.block + section.block { border-top: 1px solid var(--line); }
section.block.block-tint { background: var(--tint); }

.section-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1.8rem;
}

.section-head h2 { font-size: 1.8rem; }

/* ---------- feature grid (what we do) ---------- */

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(14.5rem, 1fr));
  gap: 1.8rem;
}

.feature-mark {
  display: inline-block;
  width: 1.9rem;
  height: 1.9rem;
  margin-bottom: 0.9rem;
}

.feature-mark.c-1 { background: var(--primary); }
.feature-mark.c-2 { background: var(--secondary); }
.feature-mark.c-3 { background: var(--accent); }
.feature-mark.c-4 { background: var(--panel); }

.feature h3 { font-size: 1.1rem; }
.feature p { margin: 0; color: var(--muted-text); font-size: 0.96rem; }

/* ---------- cards ---------- */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(15.5rem, 1fr));
  gap: 1.6rem;
}

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  padding: 1.4rem;
}

.card h3 { font-size: 1.12rem; margin-bottom: 0.4em; }
.card h3 a { color: var(--ink); text-decoration: none; }
.card h3 a:hover { color: var(--link); }
.card p { margin: 0; color: var(--muted-text); font-size: 0.96rem; }
.card .eyebrow, .card .meta { margin-bottom: 0.5em; }

.meta {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: var(--secondary);
  letter-spacing: 0.03em;
}

.tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  background: var(--accent);
  color: var(--accent-ink);
  padding: 0.25rem 0.6rem;
  margin-bottom: 0.7em;
}

/* ---------- cta block ---------- */

.cta-block { background: var(--primary); color: #fff; }
.cta-block h2 { color: #fff; }
.cta-block p { color: var(--primary-ink-muted); margin: 0; }

.cta-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1.6rem;
}

.cta-block .btn-primary { background: var(--panel); border-color: var(--panel); color: var(--panel-ink); }
.cta-block .btn-primary:hover { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }

/* ---------- generic page / article ---------- */

.page-head {
  padding: 3rem 0 2rem;
  border-bottom: 1px solid var(--line);
}

.page-head h1 { font-size: clamp(2rem, 4vw, 2.6rem); }

article.prose { padding: 2.5rem 0; max-width: 42rem; }
article.prose h2 { font-size: 1.4rem; margin-top: 1.6em; }
article.prose p { margin: 0 0 1.1em; }
article.prose ul { padding-left: 1.2em; }
article.prose li { margin-bottom: 0.4em; }

/* ---------- library ---------- */

.library { padding-bottom: 3.5rem; font-size: 0.94rem; }

.library-search { margin-bottom: 1.1rem; }

.library-search-input {
  width: 100%;
  max-width: 26rem;
  font-family: var(--font-body);
  font-size: 0.95rem;
  padding: 0.6rem 0.85rem;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink);
}

.library-search-input:focus { border-color: var(--primary); }

.library-search-input::-webkit-search-cancel-button { cursor: pointer; }

.library-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 2rem;
}

.tag-filter {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 0.4rem 0.75rem;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--muted-text);
  cursor: pointer;
}

.tag-filter:hover { border-color: var(--primary); color: var(--link); }

.tag-filter.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

.library-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

.library-entry {
  display: flex;
  gap: 1.6rem;
  padding: 1.6rem 0;
  border-bottom: 1px solid var(--line);
}

.library-year {
  flex: 0 0 4.5rem;
  font-family: var(--font-display);
  font-size: 2.1rem;
  font-weight: 600;
  line-height: 1;
  color: var(--primary);
}

.library-type {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--secondary);
  margin: 0 0 0.35em;
}

.library-title {
  font-size: 1.05rem;
  margin: 0 0 0.4em;
}

.library-citation {
  font-size: 0.86rem;
  color: var(--ink);
  margin: 0 0 0.7em;
}

.library-venue { font-style: italic; color: var(--muted-text); }

.library-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin-bottom: 0.7em;
}

.library-tags .chip {
  font-family: var(--font-mono);
  font-size: 0.64rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  padding: 0.18rem 0.5rem;
  border: 1px solid var(--line);
  background: var(--tint);
  color: var(--secondary);
}

.library-link {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.02em;
}

.library-year.resource-index { color: var(--secondary); }

@media (max-width: 40rem) {
  .library-entry { flex-direction: column; gap: 0.5rem; }
  .library-year { font-size: 1.6rem; }
}

/* ---------- forms ---------- */

form.register {
  display: grid;
  gap: 1.1rem;
  max-width: 32rem;
  margin-top: 1.8rem;
}

form.register label {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--link);
  margin-bottom: 0.4em;
}

form.register input,
form.register select,
form.register textarea {
  width: 100%;
  font-family: var(--font-body);
  font-size: 1rem;
  padding: 0.65rem 0.75rem;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink);
}

form.register input:focus,
form.register select:focus,
form.register textarea:focus {
  border-color: var(--primary);
}

form.register textarea { min-height: 6rem; resize: vertical; }

.form-actions {
  display: flex;
  gap: 0.9rem;
  flex-wrap: wrap;
}

form.register button {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 0.85rem 1.6rem;
  cursor: pointer;
  border: 1px solid var(--primary);
}

form.register button.btn-submit-primary {
  background: var(--primary);
  color: #fff;
}

form.register button.btn-submit-primary:hover {
  background: var(--primary-hover);
  border-color: var(--primary-hover);
}

form.register button.btn-submit-secondary {
  background: transparent;
  color: var(--link);
}

form.register button.btn-submit-secondary:hover {
  background: var(--tint);
}

.form-note {
  font-size: 0.88rem;
  color: var(--muted-text);
  margin-top: 0.8rem;
}

/* ---------- footer ---------- */

.site-footer {
  background: var(--panel);
  color: var(--panel-ink-muted);
  padding: 1.4rem 0;
  margin-top: 2.4rem;
  font-size: 0.88rem;
}

.footer-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem 1.5rem;
}

.footer-brand {
  margin: 0;
  display: flex;
  align-items: baseline;
  gap: 0.7rem;
  flex-wrap: wrap;
}

.footer-title {
  font-family: var(--font-display);
  font-size: 1.05rem;
  color: var(--title-ink);
}

.footer-links {
  margin: 0;
  display: flex;
  align-items: baseline;
  gap: 0.55rem;
  flex-wrap: wrap;
}

.footer-links .sep { color: var(--panel-ink-muted); }

.footer-essa {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.footer-essa-link { display: inline-flex; align-items: center; line-height: 0; }

.footer-essa-logo {
  display: block;
  height: 1.6rem;
  width: auto;
  border-radius: 2px;
  vertical-align: middle;
}

.essa-logo-block {
  display: inline-block;
  margin-top: 1.4rem;
  line-height: 0;
}

.essa-logo-block img {
  display: block;
  border-radius: 4px;
}

.site-footer a { color: var(--panel-ink); }

/* ---------- responsive ---------- */

@media (max-width: 55rem) {
  .hero .wrap { grid-template-columns: 1fr; padding-top: 2.6rem; padding-bottom: 2.6rem; }
  .site-header .wrap { flex-direction: column; align-items: flex-start; gap: 0.9rem; }
  .cta-inner { flex-direction: column; align-items: flex-start; }
  .footer-row { flex-direction: column; align-items: flex-start; }
}