/* ===========================================================
   SpatialVisualization.org — Design System
   Light, elegant, professional palette tuned for long-form
   technical reading on desktop + widescreen + mobile.
   =========================================================== */

:root {
  /* Palette: cream backdrop, deep teal primary, coral accent,
     sunrise gold for spotlight CTAs, slate ink for body copy. */
  --bg:           #fbf8f2;
  --bg-elev:      #ffffff;
  --bg-soft:      #f1ebdd;
  --bg-tint:      #ecf5f4;
  --ink:          #233139;
  --ink-soft:     #4a5b65;
  --ink-mute:     #7a8a92;
  --line:         #e3dccb;
  --line-soft:    #efeadb;

  --teal:         #156a73;
  --teal-deep:    #0c4951;
  --teal-soft:    #6ab1b4;
  --coral:        #e0644d;
  --coral-soft:   #f5b8ab;
  --gold:         #d99b27;
  --gold-soft:    #f3d683;
  --violet:       #6a4a9c;
  --violet-soft:  #c4b5e3;
  --moss:         #4b8b6a;
  --moss-soft:    #a9d5b9;

  --link:         var(--teal);
  --link-hover:   var(--coral);

  --shadow-sm:    0 1px 2px rgba(35, 49, 57, 0.06), 0 1px 3px rgba(35, 49, 57, 0.04);
  --shadow-md:    0 4px 14px rgba(35, 49, 57, 0.08), 0 2px 6px rgba(35, 49, 57, 0.05);
  --shadow-lg:    0 20px 50px rgba(35, 49, 57, 0.12), 0 6px 18px rgba(35, 49, 57, 0.06);

  --radius-sm: 6px;
  --radius:    12px;
  --radius-lg: 20px;

  --header-h:   72px;
  --container:  1320px;
  --column:     74ch;

  --font-sans:  "Inter", "Segoe UI", system-ui, -apple-system, "Helvetica Neue", Arial, sans-serif;
  --font-mono:  "JetBrains Mono", "Fira Code", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --font-display: "Inter", system-ui, -apple-system, sans-serif;

  /* Fluid type scale */
  --fs-xs:   clamp(0.78rem, 0.76rem + 0.10vw, 0.86rem);
  --fs-sm:   clamp(0.88rem, 0.85rem + 0.15vw, 0.96rem);
  --fs-base: clamp(1.00rem, 0.96rem + 0.20vw, 1.10rem);
  --fs-md:   clamp(1.13rem, 1.07rem + 0.30vw, 1.25rem);
  --fs-lg:   clamp(1.30rem, 1.18rem + 0.60vw, 1.55rem);
  --fs-xl:   clamp(1.55rem, 1.30rem + 1.20vw, 2.10rem);
  --fs-2xl:  clamp(2.00rem, 1.55rem + 2.20vw, 3.00rem);
  --fs-3xl:  clamp(2.50rem, 1.80rem + 3.50vw, 4.25rem);
}

/* Reset --------------------------------------------------------- */

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--fs-base);
  line-height: 1.65;
  color: var(--ink);
  background:
    radial-gradient(1200px 600px at 110% -10%, rgba(106, 177, 180, 0.22), transparent 60%),
    radial-gradient(900px 500px at -10% 10%, rgba(243, 214, 131, 0.28), transparent 60%),
    var(--bg);
  background-attachment: fixed;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

img, svg, video { max-width: 100%; height: auto; display: block; }
button { font: inherit; cursor: pointer; }

/* Skip link */
.skip-link {
  position: absolute; top: -100px; left: 0;
  background: var(--teal); color: #fff;
  padding: 0.75rem 1.25rem;
  border-radius: 0 0 var(--radius) 0;
  z-index: 999;
  transition: top 0.2s ease;
}
.skip-link:focus { top: 0; }

/* Layout -------------------------------------------------------- */

.container {
  width: min(100% - 2rem, var(--container));
  margin-inline: auto;
}

main.site-main {
  flex: 1 0 auto;
  padding-block: clamp(2rem, 4vw, 4rem);
}

.prose-column {
  max-width: min(100%, var(--column));
}

/* Header -------------------------------------------------------- */

.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(251, 248, 242, 0.85);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--line-soft);
}
.site-header__inner {
  display: flex; align-items: center; justify-content: space-between;
  gap: 1.5rem;
  height: var(--header-h);
}
.brand {
  display: inline-flex; align-items: center; gap: 0.65rem;
  font-family: var(--font-display); font-weight: 700;
  font-size: var(--fs-md); color: var(--teal-deep);
  text-decoration: none;
  letter-spacing: -0.01em;
}
.brand:hover { color: var(--coral); }
.brand__mark { width: 36px; height: 36px; }
.brand__text { white-space: nowrap; }

.site-nav { display: flex; align-items: center; }
.site-nav__list {
  list-style: none; margin: 0; padding: 0;
  display: flex; gap: 0.25rem; flex-wrap: wrap;
}
.site-nav__link {
  display: inline-flex; align-items: center; gap: 0.45rem;
  padding: 0.55rem 0.85rem;
  border-radius: var(--radius-sm);
  font-size: var(--fs-sm); font-weight: 500;
  color: var(--ink-soft); text-decoration: none;
  transition: background 0.18s ease, color 0.18s ease, transform 0.18s ease;
}
.site-nav__link:hover {
  background: var(--bg-tint); color: var(--teal-deep); transform: translateY(-1px);
}
.site-nav__link[aria-current="page"],
.site-nav__link.is-active {
  background: linear-gradient(135deg, rgba(21, 106, 115, 0.12), rgba(224, 100, 77, 0.12));
  color: var(--teal-deep);
}
.site-nav__icon { width: 18px; height: 18px; flex: 0 0 auto; }

@media (max-width: 720px) {
  .brand__text { display: none; }
  .site-nav__link { padding: 0.45rem 0.6rem; }
  .site-nav__link span:not(.site-nav__icon-wrap) { display: none; }
}

/* Footer -------------------------------------------------------- */

.site-footer {
  flex-shrink: 0;
  margin-top: clamp(3rem, 6vw, 6rem);
  background: linear-gradient(180deg, transparent, rgba(21, 106, 115, 0.06));
  border-top: 1px solid var(--line-soft);
  padding-block: 2.5rem;
  color: var(--ink-soft);
  font-size: var(--fs-sm);
}
.site-footer__grid {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) repeat(auto-fit, minmax(180px, 1fr));
  gap: 2rem;
}
.site-footer__brand { color: var(--teal-deep); font-weight: 600; }
.site-footer__brand p { margin-top: 0.4rem; color: var(--ink-mute); }
.site-footer h2 {
  font-size: var(--fs-sm); text-transform: uppercase; letter-spacing: 0.1em;
  color: var(--teal-deep); margin: 0 0 0.65rem;
}
.site-footer ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.35rem; }
.site-footer a { color: var(--ink-soft); text-decoration: none; }
.site-footer a:hover { color: var(--coral); text-decoration: underline; }
.site-footer__base {
  margin-top: 2rem; padding-top: 1.25rem;
  border-top: 1px solid var(--line-soft);
  display: flex; justify-content: space-between; gap: 1rem; flex-wrap: wrap;
  color: var(--ink-mute);
}

/* Typography ---------------------------------------------------- */

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  color: var(--teal-deep);
  line-height: 1.2;
  margin: 2.2em 0 0.6em;
  letter-spacing: -0.015em;
  scroll-margin-top: calc(var(--header-h) + 1.5rem);
}
h1 { font-size: var(--fs-3xl); margin-top: 0; }
h2 { font-size: var(--fs-2xl); }
h3 { font-size: var(--fs-xl); color: var(--teal); }
h4 { font-size: var(--fs-lg); color: var(--teal); }
h5 { font-size: var(--fs-md); }
h6 { font-size: var(--fs-base); text-transform: uppercase; letter-spacing: 0.08em; color: var(--ink-soft); }

.page-title {
  font-size: var(--fs-3xl);
  background: linear-gradient(110deg, var(--teal-deep) 0%, var(--teal) 35%, var(--coral) 80%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  margin: 0 0 0.5em;
}

article h2 {
  position: relative;
  padding-bottom: 0.35em;
}
article h2::after {
  content: "";
  position: absolute; left: 0; bottom: 0;
  width: 56px; height: 3px; border-radius: 2px;
  background: linear-gradient(90deg, var(--coral), var(--gold));
}

article p {
  margin: 0 0 1.1em;
  font-size: var(--fs-base);
  line-height: 1.72;
  color: var(--ink);
}

article p strong { color: var(--teal-deep); }

article ul, article ol {
  margin: 0 0 1.2em 1.25em;
  padding-left: 0;
  line-height: 1.7;
}
article li + li { margin-top: 0.35em; }

article blockquote {
  margin: 1.5em 0;
  padding: 0.6em 1.2em;
  border-left: 4px solid var(--coral);
  background: var(--bg-tint);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: var(--ink-soft);
  font-style: italic;
}

article hr {
  border: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line), transparent);
  margin: 2.5em 0;
}

/* Links --------------------------------------------------------- */

a {
  color: var(--link);
  text-decoration-color: rgba(21, 106, 115, 0.35);
  text-decoration-thickness: 1.5px;
  text-underline-offset: 3px;
  transition: color 0.18s ease, text-decoration-color 0.18s ease;
}
a:hover {
  color: var(--link-hover);
  text-decoration-color: var(--coral);
}

/* Inline code (no border, soft tinted background) --------------- */

:not(pre) > code {
  font-family: var(--font-mono);
  font-size: 0.92em;
  padding: 0.12em 0.42em;
  background: rgba(21, 106, 115, 0.08);
  color: var(--teal-deep);
  border-radius: 4px;
  border: 0;
}

/* Code blocks --------------------------------------------------- */

.code-block {
  margin: 1.5em 0;
  border: 1px solid var(--line);
  background: var(--bg-elev);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}
.code-block__bar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 0.5em 0.85em;
  background: linear-gradient(180deg, var(--bg-soft), rgba(241, 235, 221, 0.6));
  border-bottom: 1px solid var(--line-soft);
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  color: var(--ink-soft);
}
.code-lang {
  text-transform: uppercase; letter-spacing: 0.1em;
  color: var(--teal);
  font-weight: 600;
}
.code-copy {
  background: transparent;
  border: 1px solid var(--line);
  color: var(--ink-soft);
  border-radius: var(--radius-sm);
  padding: 0.28em 0.7em;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  transition: background 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}
.code-copy:hover {
  background: var(--teal); color: #fff; border-color: var(--teal);
}
.code-copy.is-copied {
  background: var(--moss); color: #fff; border-color: var(--moss);
}
.code-block__pre {
  margin: 0;
  padding: 1em 1.15em;
  overflow-x: auto;
  background: var(--bg-elev);
  font-family: var(--font-mono);
  font-size: 0.92em;
  line-height: 1.6;
  color: #2c3e44;
  tab-size: 2;
}
.code-block__pre code {
  background: none; padding: 0; border: 0; color: inherit;
  font-size: inherit;
}

/* Prism token theme — light, palette-coherent */
.code-block__pre .token.comment,
.code-block__pre .token.prolog,
.code-block__pre .token.doctype,
.code-block__pre .token.cdata { color: #8a9ba2; font-style: italic; }

.code-block__pre .token.punctuation { color: #5b6a72; }

.code-block__pre .token.namespace { opacity: 0.7; }

.code-block__pre .token.property,
.code-block__pre .token.tag,
.code-block__pre .token.boolean,
.code-block__pre .token.number,
.code-block__pre .token.constant,
.code-block__pre .token.symbol,
.code-block__pre .token.deleted { color: #b34a2c; }

.code-block__pre .token.selector,
.code-block__pre .token.attr-name,
.code-block__pre .token.string,
.code-block__pre .token.char,
.code-block__pre .token.builtin,
.code-block__pre .token.inserted { color: #2f7a52; }

.code-block__pre .token.operator,
.code-block__pre .token.entity,
.code-block__pre .token.url,
.code-block__pre .language-css .token.string,
.code-block__pre .style .token.string { color: #156a73; background: transparent; }

.code-block__pre .token.atrule,
.code-block__pre .token.attr-value,
.code-block__pre .token.keyword { color: #6a4a9c; font-weight: 600; }

.code-block__pre .token.function,
.code-block__pre .token.class-name { color: #156a73; font-weight: 600; }

.code-block__pre .token.regex,
.code-block__pre .token.important,
.code-block__pre .token.variable { color: #b8861f; }

.code-block__pre .token.important,
.code-block__pre .token.bold { font-weight: 700; }
.code-block__pre .token.italic { font-style: italic; }

.code-block__pre .token.entity { cursor: help; }

/* WGSL-specific shader semantics */
.code-block__pre.language-wgsl .token.attribute { color: #c25827; font-weight: 600; }
.code-block__pre.language-wgsl .token.builtin { color: #156a73; font-weight: 600; }

/* Tables -------------------------------------------------------- */

.table-wrap {
  overflow-x: auto;
  margin: 1.5em 0;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--bg-elev);
  box-shadow: var(--shadow-sm);
}
.table-wrap table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--fs-sm);
}
.table-wrap th, .table-wrap td {
  padding: 0.7em 0.9em;
  text-align: left;
  border-bottom: 1px solid var(--line-soft);
  vertical-align: top;
}
.table-wrap th {
  background: var(--bg-soft);
  color: var(--teal-deep);
  font-weight: 600;
  letter-spacing: 0.02em;
  position: sticky; top: 0;
}
.table-wrap tr:nth-child(even) td { background: rgba(241, 235, 221, 0.35); }
.table-wrap tr:hover td { background: var(--bg-tint); }

/* Task-list checkboxes ----------------------------------------- */

.task-list-item {
  list-style: none;
  position: relative;
  padding-left: 0;
  margin-left: -1.25em;
}
ul:has(> .task-list-item) {
  list-style: none;
  margin-left: 0.25em;
  padding-left: 0;
}
.task-list-item-checkbox {
  appearance: none;
  -webkit-appearance: none;
  width: 1.1em; height: 1.1em;
  margin: 0 0.55em -0.18em 0;
  border: 1.5px solid var(--teal);
  border-radius: 5px;
  background: var(--bg-elev);
  cursor: pointer;
  vertical-align: middle;
  position: relative;
  transition: background 0.18s ease, border-color 0.18s ease, transform 0.18s ease;
}
.task-list-item-checkbox:hover { transform: scale(1.05); border-color: var(--coral); }
.task-list-item-checkbox:checked {
  background: linear-gradient(135deg, var(--teal), var(--coral));
  border-color: var(--teal);
}
.task-list-item-checkbox:checked::after {
  content: "";
  position: absolute;
  left: 50%; top: 46%;
  width: 0.32em; height: 0.62em;
  border: solid #fff;
  border-width: 0 2px 2px 0;
  transform: translate(-50%, -55%) rotate(45deg);
}
.task-list-item.is-checked,
.task-list-item:has(.task-list-item-checkbox:checked) {
  color: var(--ink-mute);
  text-decoration: line-through;
  text-decoration-color: rgba(122, 138, 146, 0.6);
}

/* Buttons ------------------------------------------------------- */

.btn {
  display: inline-flex; align-items: center; gap: 0.7rem;
  padding: 0.85rem 1.25rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: var(--fs-sm);
  text-decoration: none;
  border: 1px solid transparent;
  transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease, color 0.18s ease, border-color 0.18s ease;
  background: var(--bg-elev);
  color: var(--teal-deep);
  border-color: var(--line);
  box-shadow: var(--shadow-sm);
}
.btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  color: var(--teal-deep);
  border-color: var(--teal-soft);
}
.btn--primary {
  background: linear-gradient(135deg, var(--teal-deep), var(--teal));
  color: #fff;
  border-color: transparent;
}
.btn--primary:hover { color: #fff; }
.btn__icon {
  width: 28px; height: 28px;
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.85);
  color: var(--teal-deep);
  flex: 0 0 auto;
}
.btn--primary .btn__icon { background: rgba(255, 255, 255, 0.18); color: #fff; }

/* Hero ---------------------------------------------------------- */

.hero {
  text-align: center;
  padding: clamp(2rem, 5vw, 4rem) 0 clamp(1rem, 3vw, 2rem);
}
.hero__logo {
  display: block;
  margin: 0 auto 2rem;
  width: clamp(120px, 18vw, 220px);
  height: auto;
  filter: drop-shadow(0 10px 30px rgba(21, 106, 115, 0.2));
}
.hero__title {
  font-size: var(--fs-3xl);
  background: linear-gradient(120deg, var(--teal-deep) 0%, var(--teal) 30%, var(--coral) 70%, var(--gold) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  margin: 0 0 0.6em;
  line-height: 1.05;
}
.hero__lede {
  max-width: 56rem;
  margin: 0 auto 1em;
  font-size: var(--fs-md);
  color: var(--ink-soft);
  line-height: 1.65;
}
.hero__ctas {
  margin-top: 2.5rem;
  display: flex; flex-wrap: wrap; gap: 0.9rem; justify-content: center;
}

/* Section cards (homepage + section landing) ------------------- */

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.25rem;
  margin: 2rem 0;
}
.card {
  display: block;
  padding: 1.5rem 1.4rem;
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  text-decoration: none;
  color: var(--ink);
  box-shadow: var(--shadow-sm);
  transition: transform 0.22s ease, box-shadow 0.22s ease, border-color 0.22s ease;
  position: relative; overflow: hidden;
}
.card::before {
  content: "";
  position: absolute; inset: 0 0 auto 0;
  height: 4px;
  background: linear-gradient(90deg, var(--teal), var(--coral), var(--gold));
  opacity: 0.55;
  transform: scaleX(0.4);
  transform-origin: left;
  transition: transform 0.3s ease, opacity 0.3s ease;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--teal-soft);
  color: var(--ink);
}
.card:hover::before { transform: scaleX(1); opacity: 1; }
.card__icon {
  width: 40px; height: 40px;
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: 12px;
  background: var(--bg-tint);
  color: var(--teal);
  margin-bottom: 0.85rem;
}
.card__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--fs-md);
  color: var(--teal-deep);
  margin: 0 0 0.4rem;
}
.card__desc {
  margin: 0;
  color: var(--ink-soft);
  font-size: var(--fs-sm);
  line-height: 1.55;
}

/* Breadcrumbs --------------------------------------------------- */

.breadcrumbs {
  margin: 0 0 1.4rem;
  font-size: var(--fs-sm);
  color: var(--ink-mute);
  display: flex; flex-wrap: wrap; gap: 0.35rem; align-items: center;
}
.breadcrumbs a { color: var(--ink-soft); text-decoration: none; }
.breadcrumbs a:hover { color: var(--coral); text-decoration: underline; }
.breadcrumbs__sep { color: var(--line); }
.breadcrumbs__current { color: var(--teal-deep); font-weight: 600; }

/* Related pages ------------------------------------------------- */

.related {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--line-soft);
}
.related h2 { font-size: var(--fs-lg); margin-top: 0; }

/* FAQ / accordion ---------------------------------------------- */

details.faq,
article details {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 0.9em 1.1em;
  margin: 0.6em 0;
  transition: box-shadow 0.18s ease, border-color 0.18s ease;
}
article details[open] { box-shadow: var(--shadow-sm); border-color: var(--teal-soft); }
article details > summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--teal-deep);
  list-style: none;
  display: flex; align-items: center; justify-content: space-between;
  gap: 1rem;
}
article details > summary::-webkit-details-marker { display: none; }
article details > summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 1.2em;
  color: var(--coral);
  transition: transform 0.2s ease;
}
article details[open] > summary::after { content: "−"; }

/* Mermaid ------------------------------------------------------- */

.mermaid {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1rem;
  margin: 1.5em 0;
  text-align: center;
  overflow-x: auto;
}

/* KaTeX --------------------------------------------------------- */

.math-display {
  overflow-x: auto;
  padding: 0.6em 0;
  margin: 1em 0;
}

/* Article body -------------------------------------------------- */

.article-body { min-width: 0; }

/* Article prose fills the container width on desktop while keeping
   line-length readable. Paragraphs themselves stay readable because
   of the container's max-width (1320px); we don't constrain article
   width further so deep pages match section pages. */

/* Selection ----------------------------------------------------- */

::selection {
  background: rgba(224, 100, 77, 0.25);
  color: var(--teal-deep);
}

/* Focus --------------------------------------------------------- */

:focus-visible {
  outline: 3px solid rgba(21, 106, 115, 0.45);
  outline-offset: 2px;
  border-radius: 4px;
}

/* Section pages ------------------------------------------------- */

.section-intro {
  background: linear-gradient(135deg, rgba(106, 177, 180, 0.18), rgba(243, 214, 131, 0.18));
  border: 1px solid var(--line);
  padding: 1.6rem 1.8rem;
  border-radius: var(--radius-lg);
  margin-bottom: 2.5rem;
}
.section-intro p:last-child { margin-bottom: 0; }

/* Print --------------------------------------------------------- */

@media print {
  .site-header, .site-footer, .code-copy { display: none !important; }
  body { background: #fff; }
  a { color: var(--ink); text-decoration: underline; }
}