/* Set by assets/site-mode.js from data/site-config.js */
html[data-site-mode="contributions"] .show-if-problems {
  display: none !important;
}
html[data-site-mode="problems"] .show-if-contributions {
  display: none !important;
}

:root {
  --bg: #faf6ef;
  --bg-soft: #f3ecdf;
  --bg-softer: #f7f1e4;
  --ink: #1c1a17;
  --ink-soft: #4a463f;
  --muted: #8a8278;
  --rule: #e3dccd;
  --rule-soft: #efe8d9;
  --accent: #7a2e1f;
  --accent-soft: #b14a32;
  --accent-pale: #d9a597;
  --serif: "Cormorant Garamond", "Iowan Old Style", Georgia, serif;
  --brand-display: "Cinzel", "Cormorant Garamond", Georgia, serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --mono: ui-monospace, "SFMono-Regular", Menlo, monospace;
  --deva: "Shobhika", "Tiro Devanagari Sanskrit", "Noto Serif Devanagari", "Noto Sans Devanagari", serif;

  --measure: 64ch;
  --pad-x: clamp(1.25rem, 4vw, 2.5rem);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 19px;
  line-height: 1.55;
  font-feature-settings: "onum", "kern";
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-soft); text-decoration: underline; text-underline-offset: 3px; }

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

code, pre, kbd { font-family: var(--mono); font-size: 0.92em; }

[lang="sa"] { font-family: var(--deva); font-feature-settings: "kern"; }

/* ---------- header / nav ---------- */
.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.95rem var(--pad-x) 0.7rem;
  border-bottom: 1px solid var(--rule);
  max-width: 1080px;
  margin: clamp(0.85rem, 2.2vw, 1.35rem) auto 0;
  gap: 1rem;
  flex-wrap: wrap;
}
.brand {
  display: inline-flex;
  align-items: center;
  color: inherit;
  line-height: 1;
  text-decoration: none;
  flex-shrink: 0;
  min-width: min-content;
}
.brand:hover {
  text-decoration: none;
  color: inherit;
}
.brand:hover .brand-name { color: var(--accent-soft); }
.brand:hover .brand-sup { opacity: 0.92; }
.brand:hover .brand-rule { opacity: 0.55; }

.brand-stack {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 0.28rem;
  line-height: 1;
  flex-shrink: 0;
}

/* —— PROJECT between rules (reference lockup) —— */
.brand-project-row {
  display: flex;
  align-items: center;
  gap: 0.39rem;
  width: 100%;
  min-height: 1px;
}
.brand-rule {
  flex: 1 1 0;
  height: 1px;
  min-width: 0.44rem;
  background: var(--accent);
  opacity: 0.28;
}
.brand-sup {
  font-family: var(--brand-display);
  font-size: 0.55rem;
  font-weight: 600;
  letter-spacing: 0.32em;
  text-transform: uppercase;
  color: var(--accent);
  padding: 0 0.05em 0 0.22em; /* optical center for wide tracking */
  white-space: nowrap;
  line-height: 1;
}

/* —— main wordmark (reference: large caps, high-contrast serif, open tracking) —— */
.brand-name {
  font-family: var(--brand-display);
  font-size: clamp(0.82rem, 2vw, 1.48rem);
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  text-align: center;
  line-height: 1.05;
  white-space: nowrap;
  margin: 0;
  padding: 0.03em 0 0;
  font-feature-settings: "kern" 1;
  -webkit-font-smoothing: antialiased;
}
.site-nav {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  justify-content: flex-end;
  font-family: var(--sans);
  font-size: 0.92rem;
  flex-shrink: 1;
  min-width: 0;
}
.site-nav a { color: var(--ink-soft); }
.site-nav a:hover { color: var(--accent); text-decoration: none; }
.site-nav a[aria-current="page"] { color: var(--accent); }

@media (max-width: 440px) {
  .brand-sup {
    font-size: 0.485rem;
    letter-spacing: 0.2em;
    padding-left: 0.18em;
  }
  .brand-project-row { gap: 0.28rem; }
  .brand-name {
    font-size: 0.63rem;
    letter-spacing: 0.1em;
  }
}

/* ---------- main ---------- */
main {
  max-width: 1080px;
  margin: 0 auto;
  padding: 2rem var(--pad-x) 4rem;
}

/* ---------- hero ---------- */
.hero {
  padding: 3rem 0 3.5rem;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 3rem;
}
.kicker {
  font-family: var(--deva);
  color: var(--accent);
  letter-spacing: 0.18em;
  text-transform: lowercase;
  margin: 0 0 1rem;
  font-size: 0.95rem;
}
.hero h1 {
  font-family: var(--serif);
  font-weight: 500;
  font-size: clamp(2.2rem, 5vw, 3.6rem);
  line-height: 1.08;
  letter-spacing: -0.01em;
  margin: 0 0 1.4rem;
  max-width: 22ch;
}
.hero h1 em { color: var(--accent); font-style: italic; }
.lede {
  max-width: var(--measure);
  font-size: 1.12rem;
  color: var(--ink-soft);
  margin: 0 0 2rem;
}
.hero-cta { display: flex; flex-wrap: wrap; gap: 0.75rem; }

.about-section {
  padding-bottom: 1rem;
  max-width: var(--measure);
}
.about-section h2 {
  font-family: var(--serif);
  font-weight: 500;
  font-size: clamp(1.5rem, 3vw, 1.95rem);
  margin: 0 0 1rem;
  letter-spacing: -0.02em;
  color: var(--ink);
}
.about-section p {
  font-size: 1.08rem;
  line-height: 1.7;
  color: var(--ink-soft);
  margin: 0 0 1.1rem;
}
.about-section p:last-child { margin-bottom: 0; }

.btn {
  display: inline-block;
  padding: 0.65rem 1.2rem;
  background: var(--accent);
  color: var(--bg);
  font-family: var(--sans);
  font-size: 0.92rem;
  font-weight: 500;
  border: 1px solid var(--accent);
  border-radius: 2px;
  cursor: pointer;
  letter-spacing: 0.02em;
}
.btn:hover { background: var(--accent-soft); border-color: var(--accent-soft); color: var(--bg); text-decoration: none; }
.btn-ghost {
  background: transparent;
  color: var(--ink);
  border-color: var(--ink);
}
.btn-ghost:hover { background: var(--ink); color: var(--bg); }

/* ---------- problems block ---------- */
.problems-head {
  margin-bottom: 1.8rem;
}
.problems-head h2 {
  font-weight: 500;
  font-size: 1.6rem;
  margin: 0;
  letter-spacing: -0.005em;
}
.problems-sub {
  font-family: var(--sans);
  font-size: 0.88rem;
  color: var(--ink-soft);
  line-height: 1.45;
  margin: 0.65rem 0 0;
  max-width: var(--measure);
}

/* ---------- archive head (used on archive.html) ---------- */
.page-head {
  padding: 2.5rem 0 2rem;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 2rem;
}
.page-head h1 {
  font-family: var(--serif);
  font-weight: 500;
  font-size: clamp(2rem, 4vw, 2.6rem);
  margin: 0 0 0.6rem;
  letter-spacing: -0.005em;
}

.problems-empty {
  font-family: var(--sans);
  color: var(--muted);
  font-size: 0.95rem;
  padding: 1.5rem 0;
}

/* ---------- problem list ---------- */
.problem-list {
  list-style: none;
  margin: 0;
  padding: 0;
}
.problem-row {
  display: grid;
  grid-template-columns: 3rem 1fr auto;
  align-items: baseline;
  gap: 1rem;
  padding: 0.9rem 0.4rem;
  border-bottom: 1px solid var(--rule-soft);
  color: var(--ink);
}
a.problem-row { text-decoration: none; color: inherit; }
.problem-row--locked {
  cursor: default;
  opacity: 0.92;
}
.problem-row--locked:hover {
  background: transparent;
}
.problem-row:hover {
  background: var(--bg-softer);
  text-decoration: none;
  color: var(--ink);
}
.problem-row .pn {
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--muted);
  letter-spacing: 0.04em;
  font-variant-numeric: tabular-nums;
}
.problem-row .pt {
  font-size: 1.1rem;
  line-height: 1.3;
  color: var(--ink);
}
.problem-row-meta {
  display: block;
  margin-top: 0.35rem;
  font-family: var(--sans);
  font-size: 0.78rem;
  color: var(--muted);
  letter-spacing: 0.02em;
  font-weight: 400;
}

/* ---------- footer ---------- */
.site-foot {
  max-width: 1080px;
  margin: 0 auto;
  padding: 2rem var(--pad-x) 3rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--muted);
}
.site-foot p { margin: 0; }

/* ---------- problem page ---------- */
.problem-page { max-width: 760px; padding-top: 2rem; }

.problem-pager {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--sans);
  font-size: 0.88rem;
  padding: 0.5rem 0;
  margin-bottom: 2rem;
}
.problem-pager.top { border-top: 1px solid var(--rule-soft); border-bottom: 1px solid var(--rule-soft); padding: 0.7rem 0; }
.problem-pager:not(.top) { border-top: 1px solid var(--rule-soft); margin-top: 3rem; padding-top: 1.2rem; }
.pager-link { color: var(--ink-soft); }
.pager-link:hover { color: var(--accent); text-decoration: none; }
.pager-link.disabled { color: var(--rule); pointer-events: none; }
.pager-pos { color: var(--muted); font-size: 0.82rem; font-family: var(--sans); }

.problem-article {
  font-size: 1.12rem;
  line-height: 1.7;
}
.problem-article h1 {
  font-weight: 500;
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  line-height: 1.15;
  margin: 0 0 0.65rem;
  letter-spacing: -0.005em;
}
/* TeX fragments — MathJax replaces math; prose stays as plain text */
.problem-article .body.problem-tex {
  white-space: pre-wrap;
  margin: 0;
  padding: 0;
}
.problem-article p { margin: 0 0 1.1rem; }
.problem-article ul { padding-left: 1.2rem; margin: 0 0 1.1rem; }
.problem-article li { margin: 0.3rem 0; }
.problem-article blockquote {
  border-left: 2px solid var(--accent);
  background: var(--bg-soft);
  margin: 1.4rem 0;
  padding: 0.9rem 1.2rem;
  font-style: italic;
  color: var(--ink-soft);
}
.problem-article blockquote cite {
  display: block;
  font-style: normal;
  font-family: var(--sans);
  font-size: 0.78rem;
  color: var(--muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-top: 0.5rem;
}
.problem-article .math {
  display: block;
  text-align: center;
  margin: 1.25rem 0;
  font-style: normal;
}
.problem-article mjx-container[display="true"] {
  margin: 0.4rem auto;
}
.problem-locked-lede {
  font-size: 1.12rem;
  color: var(--ink-soft);
  max-width: var(--measure);
  margin: 0 0 1.25rem;
  padding: 1rem 1.2rem;
  background: var(--bg-soft);
  border-left: 3px solid var(--accent);
}
.problem-locked-hint {
  font-family: var(--sans);
  font-size: 0.92rem;
  margin: 0;
}

.frac {
  display: inline-block;
  vertical-align: middle;
  text-align: center;
  font-style: normal;
  margin: 0 0.15em;
}
.frac .num { display: block; border-bottom: 1px solid currentColor; padding: 0 0.3em; }
.frac .den { display: block; padding: 0 0.3em; }
sup, sub { font-size: 0.7em; line-height: 0; }

/* ---------- prose page ---------- */
.page-prose .prose {
  max-width: var(--measure);
  margin: 0 auto;
  padding: 2rem var(--pad-x) 4rem;
}
.prose h1 {
  font-weight: 500;
  font-size: clamp(2rem, 4.5vw, 3rem);
  margin: 0.5rem 0 1.5rem;
  letter-spacing: -0.005em;
}
.prose h2 {
  font-weight: 500;
  font-size: 1.5rem;
  margin: 2.5rem 0 0.8rem;
  letter-spacing: -0.005em;
}
.prose p, .prose li { font-size: 1.08rem; line-height: 1.7; }
.prose .lede { font-size: 1.2rem; color: var(--ink-soft); }
.prose ul { padding-left: 1.2rem; }
.prose li { margin: 0.4rem 0; }
.prose .colophon {
  margin-top: 3rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: 0.85rem;
  color: var(--muted);
}

/* ---------- contribute sample carousel ---------- */
.sample-carousel {
  margin: 0 0 2.25rem;
}
.sample-carousel__header {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.75rem 1rem;
  margin-bottom: 0.75rem;
}
.sample-carousel__title {
  font-family: var(--sans);
  font-size: 0.84rem;
  font-weight: 300;
  letter-spacing: 0.02em;
  color: color-mix(in srgb, var(--muted) 62%, var(--bg));
  margin: 0;
}
.sample-carousel__toolbar {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.sample-carousel__arrow {
  font-family: var(--sans);
  font-size: 1rem;
  line-height: 1;
  padding: 0.35rem 0.55rem;
  background: var(--bg-soft);
  border: 1px solid var(--rule);
  border-radius: 2px;
  color: var(--ink-soft);
  cursor: pointer;
}
.sample-carousel__arrow:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.sample-carousel__arrow:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(122, 46, 31, 0.12);
}
.sample-carousel__dots {
  display: flex;
  gap: 0.35rem;
}
.sample-carousel__dot {
  font-family: var(--sans);
  font-size: 0.72rem;
  min-width: 1.65rem;
  height: 1.65rem;
  padding: 0 0.35rem;
  border-radius: 999px;
  border: 1px solid var(--rule);
  background: var(--bg);
  color: var(--ink-soft);
  cursor: pointer;
  line-height: 1;
}
.sample-carousel__dot.is-active {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--bg);
}
.sample-carousel__dot:hover:not(.is-active) {
  border-color: var(--accent-soft);
  color: var(--accent);
}
.sample-carousel__dot:focus {
  outline: none;
  box-shadow: 0 0 0 3px rgba(122, 46, 31, 0.12);
}
.sample-carousel__viewport {
  overflow: hidden;
  border: 1px solid var(--rule);
  border-radius: 3px;
  background: var(--bg-softer);
  outline: none;
  /* Height set by JS to match the active slide (short slides stay short). */
  min-height: 0;
  /* No transition until .is-ready — avoids a tall-then-shrink flash on load. */
  transition: none;
}
.sample-carousel.is-ready .sample-carousel__viewport {
  transition: height 0.28s ease;
}
/* Hide until first layout pass — use max-height (not height:0) so slide offsetHeight stays measurable */
.sample-carousel.is-booting .sample-carousel__viewport {
  visibility: hidden;
  max-height: 0;
  min-height: 0;
  overflow: hidden;
  opacity: 0;
  pointer-events: none;
  border-width: 0;
  padding: 0;
  margin: 0;
}
.sample-carousel__viewport:focus-visible {
  box-shadow: 0 0 0 3px rgba(122, 46, 31, 0.15);
}
.sample-carousel__track {
  display: flex;
  align-items: flex-start;
  transition: transform 0.55s ease;
  will-change: transform;
}
.sample-carousel__slide {
  flex: 0 0 100%;
  min-width: 0;
  padding: 0.85rem 1rem 1rem;
  box-sizing: border-box;
}
.sample-carousel__slide.problem-article {
  font-size: 1.05rem;
  line-height: 1.5;
}
.sample-carousel__meta {
  font-family: var(--sans);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 0.45rem;
}
.sample-carousel__slide .body.problem-tex {
  white-space: pre-wrap;
  margin: 0;
  padding: 0;
}
/* Tighter MathJax than full problem page — default CHTML margins read very large here */
.sample-carousel mjx-container {
  margin: 0.12em 0 !important;
}
.sample-carousel mjx-container[display="true"] {
  margin: 0.35em 0 !important;
}
@media (prefers-reduced-motion: reduce) {
  .sample-carousel__track {
    transition: none;
  }
  .sample-carousel.is-ready .sample-carousel__viewport {
    transition: none;
  }
}

/* ---------- contribute form ---------- */
.contrib-form {
  margin-top: 2.2rem;
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}
.contrib-form .field {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  flex: 1 1 0;
  min-width: 0;
}
.contrib-form .field-row {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}
.contrib-form .field-row > .field {
  min-width: 200px;
}
.contrib-form label {
  font-family: var(--sans);
  font-size: 0.78rem;
  color: var(--ink-soft);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.contrib-form label .opt {
  margin-left: 0.4rem;
  color: var(--muted);
  font-size: 0.72rem;
  text-transform: lowercase;
  letter-spacing: 0.02em;
  font-style: italic;
}
.contrib-form input[type="text"],
.contrib-form input[type="email"],
.contrib-form select,
.contrib-form textarea {
  font-family: var(--serif);
  font-size: 1.02rem;
  padding: 0.6rem 0.8rem;
  background: var(--bg);
  border: 1px solid var(--rule);
  border-radius: 2px;
  color: var(--ink);
  width: 100%;
  line-height: 1.5;
}
.contrib-form textarea {
  resize: vertical;
  min-height: 5rem;
  font-family: var(--serif);
}
.contrib-form input:focus,
.contrib-form select:focus,
.contrib-form textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(122, 46, 31, 0.12);
}
.contrib-form select {
  appearance: none;
  background-image: linear-gradient(45deg, transparent 50%, var(--ink-soft) 50%),
                    linear-gradient(135deg, var(--ink-soft) 50%, transparent 50%);
  background-position: calc(100% - 18px) 55%, calc(100% - 12px) 55%;
  background-size: 6px 6px;
  background-repeat: no-repeat;
  padding-right: 2rem;
}
.contrib-form .form-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
  margin-top: 0.5rem;
}
.contrib-form .form-msg {
  font-family: var(--sans);
  font-size: 0.88rem;
  color: var(--muted);
}
.contrib-form .form-msg.good { color: var(--good, var(--accent)); }
.contrib-form .form-msg.bad  { color: var(--bad, var(--accent)); }
.contrib-form .form-note {
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--muted);
  margin: 0.5rem 0 0;
}

::selection { background: var(--accent); color: var(--bg); }

@media (max-width: 600px) {
  .problem-row { grid-template-columns: 2.6rem 1fr auto; }
  .problem-row .pt { font-size: 1rem; }
}