/* Turtle Research — turtleresearch.org
   Single stylesheet. No build step, no framework. Edit in place. */

:root {
  --paper:        #d9d9d9;
  --paper-alt:    #cfcfcf;
  --ink:          #000000;
  --ink-soft:     #2e2e2e;
  --ink-faint:    #5c5c5c;
  --rule:         #b4b4b4;
  --accent:       #1a1a1a;
  --accent-soft:  #c6c6c6;
  --shell:        rgba(0, 0, 0, 0.06);

  --serif: "Newsreader", ui-serif, Georgia, "Iowan Old Style", "Times New Roman", serif;
  --sans:  ui-sans-serif, system-ui, -apple-system, "Segoe UI", Inter, Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono:  ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;

  /* Measure matches the wrap at Thomas's request, so prose fills the page
     container rather than sitting in a narrower column inside it. */
  --measure: 72rem;
  --wrap: 72rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper:       #2b2b2b;
    --paper-alt:   #232323;
    --ink:         #f2f2f2;
    --ink-soft:    #c2c2c2;
    --ink-faint:   #8f8f8f;
    --rule:        #454545;
    --accent:      #ededed;
    --accent-soft: #383838;
    --shell:       rgba(255, 255, 255, 0.06);
  }
}

*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 5rem;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: clamp(1.0625rem, 0.99rem + 0.35vw, 1.1875rem);
  line-height: 1.78;
  font-optical-sizing: auto;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: clamp(1.25rem, 5vw, 3.5rem);
}

.skip {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--accent);
  color: var(--paper);
  padding: 0.6rem 1rem;
  z-index: 10;
}
.skip:focus { left: 0.5rem; top: 0.5rem; }

a { color: inherit; }

:where(a, .brand):focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ── Masthead ───────────────────────────────────────────── */

.masthead {
  position: sticky;
  top: 0;
  z-index: 5;
  background: var(--paper); /* fallback where color-mix is unsupported */
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  -webkit-backdrop-filter: saturate(1.4) blur(10px);
  backdrop-filter: saturate(1.4) blur(10px);
  border-bottom: 1px solid var(--rule);
}

.masthead-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  min-height: 4.25rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: var(--ink);
}

.brand-mark {
  width: 1.6rem;
  height: 1.6rem;
  flex: none;
  color: var(--accent);
}

.brand-text {
  font-size: 1.0625rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-family: var(--sans);
  font-weight: 600;
}

.nav {
  display: flex;
  gap: clamp(0.9rem, 2.5vw, 1.9rem);
  font-family: var(--sans);
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.nav a {
  text-decoration: none;
  color: var(--ink-soft);
  padding-block: 0.35rem;
  border-bottom: 1px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.nav a:hover { color: var(--ink); border-bottom-color: var(--accent); }

/* ── Hero ───────────────────────────────────────────────── */

.hero {
  position: relative;
  overflow: hidden;
  padding-block: clamp(4rem, 11vw, 8.5rem) clamp(3rem, 7vw, 5.5rem);
  border-bottom: 1px solid var(--rule);
}

/* Scute lattice — a turtle shell, flattened into a background. */
.hero::before {
  content: "";
  position: absolute;
  inset: -20% -10% auto auto;
  width: min(46rem, 78vw);
  aspect-ratio: 1;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='84' height='96' viewBox='0 0 84 96'%3E%3Cg fill='none' stroke='%23000000' stroke-width='1.4'%3E%3Cpath d='M42 1 L73 19 V55 L42 73 L11 55 V19 Z'/%3E%3Cpath d='M0 49 L11 55 V91 L0 97'/%3E%3Cpath d='M84 49 L73 55 V91 L84 97'/%3E%3Cpath d='M42 73 L42 96'/%3E%3C/g%3E%3C/svg%3E");
  background-size: 84px 96px;
  opacity: 0.22;
  mask-image: radial-gradient(closest-side at 70% 30%, #000 20%, transparent 78%);
  -webkit-mask-image: radial-gradient(closest-side at 70% 30%, #000 20%, transparent 78%);
  pointer-events: none;
}
@media (prefers-color-scheme: dark) {
  .hero::before { opacity: 0.22; filter: invert(1); }
}

.hero .wrap { position: relative; }

.eyebrow {
  margin: 0 0 1.25rem;
  font-family: var(--sans);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
}

h1 {
  margin: 0;
  max-width: 30ch;
  font-size: clamp(2.1rem, 1.2rem + 4.1vw, 3.9rem);
  line-height: 1.08;
  font-weight: 400;
  letter-spacing: -0.02em;
  text-wrap: balance;
}

.lede {
  margin: 1.75rem 0 0;
  max-width: 46ch;
  font-size: clamp(1.125rem, 1.03rem + 0.45vw, 1.375rem);
  line-height: 1.55;
  color: var(--ink-soft);
  font-style: italic;
  text-wrap: pretty;
}

/* ── Sections ───────────────────────────────────────────── */

.section {
  padding-block: clamp(3.25rem, 8vw, 6rem);
}

.section-alt {
  background: var(--paper-alt);
  border-block: 1px solid var(--rule);
}

.prose { max-width: var(--measure); }

.prose p {
  margin: 0 0 1.35em;
  text-wrap: pretty;
}
.prose p:last-child { margin-bottom: 0; }

h2 {
  margin: 0 0 1.9rem;
  font-family: var(--sans);
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.marker {
  display: inline-block;
  padding-bottom: 0.55rem;
  border-bottom: 2px solid var(--accent);
}

.section-note {
  color: var(--ink-faint);
  font-size: 0.9375rem;
  font-style: italic;
}

strong { font-weight: 600; }
em { font-style: italic; }

/* ── Reactive / proactive contrast ──────────────────────── */

.contrast {
  display: grid;
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
  border-radius: 6px;
  overflow: hidden;
  margin: 2.25rem 0 2.5rem;
  max-width: 100%;
}

@media (min-width: 47rem) {
  .contrast { grid-template-columns: 1fr 1fr; }
}

.contrast-col {
  background: var(--paper);
  padding: 1.4rem 1.5rem 1.6rem;
}
.section-alt .contrast-col { background: var(--paper-alt); }
.contrast-col.is-ours { background: var(--accent-soft); }

.contrast-tag {
  margin: 0 0 0.3rem;
  font-family: var(--sans);
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-faint);
}
.is-ours .contrast-tag { color: var(--accent); }

.contrast-name {
  margin: 0 0 0.9rem;
  font-size: 1.1875rem;
  letter-spacing: -0.01em;
}

.contrast-col ul {
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 0.9375rem;
  line-height: 1.5;
  color: var(--ink-soft);
}

.contrast-col li {
  position: relative;
  padding-left: 1.1rem;
  margin-bottom: 0.55rem;
}
.contrast-col li:last-child { margin-bottom: 0; }
.contrast-col li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.6em;
  width: 0.4rem;
  height: 0.4rem;
  border: 1px solid var(--ink-faint);
  transform: rotate(45deg);
}
.is-ours li::before { border-color: var(--accent); background: var(--accent); }

/* ── Questions ──────────────────────────────────────────── */

.questions {
  list-style: none;
  margin: 2.5rem 0 0;
  padding: 0;
  display: grid;
  gap: clamp(1.5rem, 3vw, 2.25rem);
}

@media (min-width: 52rem) {
  .questions { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 78rem) {
  .questions { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

.q {
  position: relative;
  padding: 1.6rem 1.75rem 1.75rem;
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 6px;
  transition: border-color 0.18s ease, transform 0.18s ease;
}
.q:hover {
  border-color: color-mix(in srgb, var(--accent) 45%, var(--rule));
  transform: translateY(-2px);
}

.q-num {
  margin: 0 0 0.9rem;
  font-family: var(--mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  color: var(--accent);
}

.q h3 {
  margin: 0 0 0.75rem;
  font-size: 1.1875rem;
  line-height: 1.32;
  font-weight: 500;
  letter-spacing: -0.011em;
  text-wrap: pretty;
}

.q p:not(.q-num) {
  margin: 0;
  font-size: 0.9688rem;
  line-height: 1.6;
  color: var(--ink-soft);
  text-wrap: pretty;
}

/* ── Closing + footer ───────────────────────────────────── */

.contact {
  margin-top: 1.75rem;
}

.contact-link {
  display: inline-block;
  font-size: clamp(1.25rem, 1.1rem + 0.7vw, 1.625rem);
  letter-spacing: -0.01em;
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid color-mix(in srgb, var(--accent) 40%, transparent);
  padding-bottom: 0.15rem;
  transition: border-color 0.15s ease;
}
.contact-link:hover { border-bottom-color: var(--accent); }

.footer {
  border-top: 1px solid var(--rule);
  padding-block: 2.5rem 3.25rem;
  background: var(--paper);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.4rem 1.5rem;
}

.footer-brand {
  margin: 0;
  font-family: var(--sans);
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.footer-meta {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--ink-faint);
}

.footer-mail {
  margin: 0;
  font-size: 0.9375rem;
}
.footer-mail a {
  color: var(--ink-soft);
  text-decoration: none;
  border-bottom: 1px solid var(--rule);
  transition: color 0.15s ease, border-color 0.15s ease;
}
.footer-mail a:hover { color: var(--accent); border-bottom-color: var(--accent); }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}