/* ==========================================================================
   Prime Theory Labs: site styles
   --------------------------------------------------------------------------
   1. Tokens       (colors, type, spacing, radius from the brand design system)
   2. Base         (reset, typography, links, focus)
   3. Layout       (container, sections, grids)
   4. Components   (header, buttons, cards, tags, steps, footer)
   5. Sections     (hero, contact band, 404)
   To restyle the site, change the tokens in section 1 first.
   ========================================================================== */

/* 1. Tokens ---------------------------------------------------------------- */

:root {
  color-scheme: light dark;

  /* Brand colors (same in both themes) */
  --brand-cobalt: #2A45C9;  /* Proof Cobalt: primary buttons, icon tile */
  --brand-gold:   #F2B33D;  /* Golden Ratio: accent on dark only, once per view */
  --brand-ink:    #121A3A;  /* Ink Indigo: dark surfaces */
  --brand-paper:  #E9EEF8;  /* Graph Paper: light surface */

  /* Theme colors (light) */
  --surface:         #E9EEF8;
  --surface-raised:  #FFFFFF;
  --surface-inverse: #121A3A;
  --text:            #121A3A;
  --text-muted:      #5B6685;
  --link:            #2A45C9;
  --grid-line:       #C9D3EA;
  --header-bg:       rgba(233, 238, 248, 0.86);
  --band-bg:         #121A3A;  /* contact band */
  --band-text:       #FFFFFF;
  --band-muted:      #A9B2CC;

  /* Type */
  --font-sans: "Sora", system-ui, -apple-system, "Segoe UI", sans-serif;

  /* Spacing */
  --space-2: 8px;
  --space-4: 16px;
  --space-6: 24px;
  --space-12: 48px;

  /* Radius */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-icon: 22.5%;

  /* Layout */
  --container: 1120px;
  --gutter: 16px;
  --header-h: 64px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --surface:         #121A3A;
    --surface-raised:  #1C2550;
    --surface-inverse: #E9EEF8;
    --text:            #FFFFFF;
    --text-muted:      #A9B2CC;
    --link:            #8FA2F5;
    --grid-line:       #26305C;
    --header-bg:       rgba(18, 26, 58, 0.86);
    --band-bg:         #1C2550;
  }
}

@media (min-width: 640px) {
  :root { --gutter: 24px; }
}

/* 2. Base ------------------------------------------------------------------ */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-padding-top: calc(var(--header-h) + var(--space-4));
}

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
}

body {
  margin: 0;
  background: var(--surface);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 26px;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 { margin: 0; font-weight: 600; }
p, ul, ol, dl, dd { margin: 0; }
img { display: block; max-width: 100%; height: auto; }

a { color: var(--link); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }

:focus-visible {
  outline: 3px solid var(--link);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

.skip-link {
  position: absolute;
  left: var(--gutter);
  top: -100px;
  z-index: 100;
  padding: var(--space-2) var(--space-4);
  background: var(--brand-cobalt);
  color: #FFFFFF;
  border-radius: var(--radius-sm);
}
.skip-link:focus { top: var(--space-2); }

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

/* Type styles (names match the design system) */
.display {
  font-size: clamp(40px, 9vw, 56px);
  line-height: 1.07;
  letter-spacing: -0.01em;
}
.title-1 { font-size: clamp(28px, 5vw, 36px); line-height: 1.22; }
.title-2 { font-size: 24px; line-height: 32px; }
.body    { font-size: 16px; line-height: 26px; }
.small   { font-size: 14px; line-height: 22px; }
.caption { font-size: 12px; line-height: 18px; }
.lede    { font-size: 18px; line-height: 30px; color: var(--text-muted); }
.muted   { color: var(--text-muted); }

/* 3. Layout ---------------------------------------------------------------- */

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.section { padding: calc(var(--space-12) * 1.5) 0; }
.section + .section { border-top: 1px solid var(--grid-line); }

.section-head {
  max-width: 640px;
  margin-bottom: var(--space-12);
}
.section-head .eyebrow { margin-bottom: var(--space-2); }
.section-head p:last-child { margin-top: var(--space-4); }

.eyebrow {
  font-size: 14px;
  line-height: 22px;
  font-weight: 600;
  color: var(--link);
}

/* Auto-fitting grid: add cards and it reflows on its own */
.grid {
  display: grid;
  gap: var(--space-6);
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr));
}

/* 4. Components ------------------------------------------------------------ */

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--header-bg);
  -webkit-backdrop-filter: saturate(160%) blur(12px);
  backdrop-filter: saturate(160%) blur(12px);
  border-bottom: 1px solid var(--grid-line);
}
.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  height: var(--header-h);
}
.brand { display: flex; align-items: center; flex-shrink: 0; }
.brand img { height: 36px; width: auto; }

.site-nav ul {
  display: flex;
  gap: var(--space-6);
  list-style: none;
  padding: 0;
}
.site-nav a {
  color: var(--text);
  text-decoration: none;
  font-size: 15px;
  font-weight: 600;
}
.site-nav a:hover { color: var(--link); }

@media (max-width: 599px) {
  .brand img { height: 32px; }
  .site-nav ul { gap: var(--space-4); }
  .site-nav a { font-size: 14px; }
}
@media (max-width: 379px) {
  .site-nav ul { gap: 12px; }
  .site-nav a { font-size: 13px; }
}

/* Buttons */
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 48px;
  padding: 0 var(--space-6);
  border: 2px solid transparent;
  border-radius: var(--radius-md);
  font: inherit;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
}
.button-primary {
  background: var(--brand-cobalt);
  color: #FFFFFF;
}
.button-primary:hover { background: #2339A8; }
.button-secondary {
  background: transparent;
  color: var(--text);
  border-color: var(--text);
}
.button-secondary:hover { background: var(--surface-raised); }
.button-row { display: flex; flex-wrap: wrap; gap: var(--space-4); }

/* Cards */
.card {
  background: var(--surface-raised);
  border: 1px solid var(--grid-line);
  border-radius: var(--radius-md);
  padding: var(--space-6);
}
.card h3 { margin-bottom: var(--space-2); }
.card-placeholder {
  background: transparent;
  border-style: dashed;
}
.card-placeholder h3 { margin-top: var(--space-4); }

@media (min-width: 900px) {
  .card-wide { grid-column: span 2; }
}

/* Checklist inside cards */
.checklist {
  list-style: none;
  padding: 0;
  margin-top: var(--space-6);
  display: grid;
  gap: var(--space-2) var(--space-6);
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 240px), 1fr));
}
.checklist li {
  position: relative;
  padding-left: 28px;
  font-size: 15px;
  line-height: 24px;
}
.checklist li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 5px;
  width: 14px;
  height: 14px;
  border-radius: 4px;
  background: var(--brand-cobalt);
  -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 14 14'%3E%3Cpath d='M3 7.5l2.5 2.5L11 4.5' fill='none' stroke='%23000' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E") center / 14px 14px no-repeat;
          mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 14 14'%3E%3Cpath d='M3 7.5l2.5 2.5L11 4.5' fill='none' stroke='%23000' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E") center / 14px 14px no-repeat;
}
@media (prefers-color-scheme: dark) {
  .checklist li::before { background: var(--link); }
}

/* Tags */
.tag {
  display: inline-block;
  padding: 2px 10px;
  border: 1px solid var(--grid-line);
  border-radius: 999px;
  font-size: 12px;
  line-height: 18px;
  font-weight: 600;
  color: var(--text-muted);
  background: var(--surface);
}

/* App cards: copy an <article class="app-card"> block in index.html to add an app */
.app-card {
  display: grid;
  gap: var(--space-6);
  align-items: start;
}
@media (min-width: 640px) {
  .app-card { grid-template-columns: 96px 1fr; }
}
.app-icon {
  width: 96px;
  height: 96px;
  border-radius: var(--radius-icon);
  box-shadow: 0 1px 2px rgba(18, 26, 58, 0.12), 0 8px 24px rgba(18, 26, 58, 0.10);
}
.app-card .app-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2) var(--space-4);
  margin-bottom: var(--space-2);
}
.app-card .app-features {
  list-style: none;
  padding: 0;
  margin-top: var(--space-4);
  display: grid;
  gap: var(--space-4);
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 200px), 1fr));
}
.app-card .app-features strong { display: block; font-weight: 600; }
.app-card .app-features span { font-size: 14px; line-height: 22px; color: var(--text-muted); }
.app-card .app-link { margin-top: var(--space-6); font-weight: 600; }

/* Numbered steps */
.steps {
  list-style: none;
  padding: 0;
  counter-reset: step;
  display: grid;
  gap: var(--space-12) var(--space-6);
  grid-template-columns: 1fr;
}
@media (min-width: 640px)  { .steps { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 1024px) { .steps { grid-template-columns: repeat(4, 1fr); } }
.steps li { counter-increment: step; }
.steps li::before {
  content: counter(step);
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  margin-bottom: var(--space-4);
  border-radius: 10px;
  background: var(--brand-cobalt);
  color: #FFFFFF;
  font-weight: 600;
}
.steps h3 { margin-bottom: var(--space-2); }
.steps p { color: var(--text-muted); }

/* Footer */
.site-footer {
  padding: var(--space-12) 0;
  border-top: 1px solid var(--grid-line);
}
.site-footer .container {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
}
.site-footer .footer-brand {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}
.site-footer .footer-brand img { width: 36px; height: 36px; }
.site-footer nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-6);
  list-style: none;
  padding: 0;
}
.site-footer nav a { color: var(--text-muted); text-decoration: none; font-size: 14px; }
.site-footer nav a:hover { color: var(--link); text-decoration: underline; }

/* 5. Sections -------------------------------------------------------------- */

/* Graph-paper texture: a faint grid at space-12 pitch, faded at the edges */
.graph-paper {
  position: relative;
  isolation: isolate;
}
.graph-paper::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(var(--grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: var(--space-12) var(--space-12);
  background-position: center top;
  -webkit-mask-image: radial-gradient(ellipse 80% 90% at 70% 30%, #000 20%, transparent 75%);
          mask-image: radial-gradient(ellipse 80% 90% at 70% 30%, #000 20%, transparent 75%);
  opacity: 0.7;
}

/* Hero */
.hero { padding: calc(var(--space-12) * 2) 0 calc(var(--space-12) * 1.5); }
.hero .container {
  display: grid;
  gap: var(--space-12);
  align-items: center;
}
@media (min-width: 900px) {
  .hero .container { grid-template-columns: 1.25fr 1fr; }
}
.hero .eyebrow { margin-bottom: var(--space-4); }
.hero .lede { margin-top: var(--space-6); max-width: 34em; }
.hero .button-row { margin-top: var(--space-12); }

/* The "proof" card in the hero */
.proof {
  background: var(--surface-raised);
  border: 1px solid var(--grid-line);
  border-radius: var(--radius-md);
  padding: var(--space-6);
  box-shadow: 0 1px 2px rgba(18, 26, 58, 0.06), 0 16px 40px rgba(18, 26, 58, 0.08);
}
.proof dl {
  display: grid;
  grid-template-columns: max-content 1fr;
  row-gap: var(--space-4);
}
.proof dt {
  padding-right: var(--space-6);
  font-size: 14px;
  line-height: 26px;
  font-weight: 600;
  color: var(--link);
}
/* A divider above every row but the first (dt and dd share a row) */
.proof dd + dt,
.proof dd + dt + dd {
  border-top: 1px solid var(--grid-line);
  padding-top: var(--space-4);
}
.proof .qed { color: var(--text); margin-left: 4px; }

/* Contact band */
.band {
  background: var(--band-bg);
  color: var(--band-text);
  border-radius: var(--radius-md);
  padding: var(--space-12) var(--space-6);
  overflow: hidden;
}
@media (min-width: 640px) {
  .band { padding: var(--space-12); }
}
.band .eyebrow { color: var(--brand-gold); margin-bottom: var(--space-2); }
.band p { color: var(--band-muted); margin-top: var(--space-4); max-width: 36em; }
.band .button-row { margin-top: var(--space-6); }
.band .button-secondary { color: var(--band-text); border-color: var(--band-text); }
.band .button-secondary:hover { background: rgba(255, 255, 255, 0.08); }

/* 404 */
.not-found {
  min-height: 60vh;
  display: grid;
  align-content: center;
}
.not-found .symbol {
  font-size: clamp(96px, 20vw, 160px);
  line-height: 1;
  font-weight: 600;
  color: var(--link);
}
.not-found p { margin-top: var(--space-4); }
.not-found .button-row { margin-top: var(--space-6); }